Document:

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                                                                   EXHIBIT 10.10

                               PURCHASE AGREEMENT

         PURCHASE AGREEMENT, dated as of May 31, 2000, by and among FrontLine
Capital Group, a Delaware corporation ("FCG"), HQ Global Holdings, Inc., a
Delaware corporation ("Holdco"), and EOP Operating Limited Partnership, a
Delaware limited partnership (the "Investor").

         WHEREAS, HQ Global Workplaces Inc., a Delaware corporation ("Old HQ"),
and CarrAmerica Realty Corporation, a Maryland corporation ("CarrAmerica"), on
the one hand, and VANTAS Incorporated, a Nevada corporation ("VANTAS"), and FCG,
on the other hand, have entered into that certain Agreement and Plan of Merger,
dated as of January 20, 2000, as amended as of April 29, 2000 and as of May 30,
2000 (as amended, the "Merger Agreement").

         WHEREAS, pursuant to the Merger Agreement, VANTAS will merge with and
into Old HQ with Old HQ continuing as the surviving corporation with the name
"HQ Global Workplaces, Inc." (the "HQ Merger").

         WHEREAS, FCG and CarrAmerica have entered into that certain Stock
Purchase Agreement, dated as of January 20, 2000, as amended as of April 29,
2000 (as amended, the "Stock Purchase Agreement"), whereby FCG agreed to
purchase from CarrAmerica 4,130,530 (subject to recalculation as provided
therein) shares of non-voting common stock, par value $.01 per share (the "Old
HQ Common Stock"), of Old HQ.

         WHEREAS, immediately following the consummation of the HQ Merger and
the transactions contemplated by the Stock Purchase Agreement and that certain
Stock Purchase Agreement, dated as of January 20, 2000, as amended as of April
29, 2000, among FCG, VANTAS, CarrAmerica, Omni Offices UK Limited ("Omni UK")
and Omni Offices (Lux) 1929 Holding Company S.A. ("Omni Lux") (the "UK Stock
Purchase Agreement"), Old HQ, as the surviving corporation of the HQ Merger ("HQ
Surviving Corporation"), will merge (the "Second Step Merger") with and into
newly formed HQ Merger Subsidiary, Inc., a Delaware corporation ("M-Sub") that
is a wholly owned subsidiary of Holdco, which will theretofore be wholly owned
by HQ Surviving Corporation, with M-Sub continuing as the surviving corporation
under the name "HQ Global Workplaces Inc." pursuant to the Agreement and Plan of
Merger related thereto (the "Second Step Merger Agreement").

         WHEREAS, pursuant to the Exchange Agreement, dated as of May 31, 2000
(the "Exchange Agreement"), Holdco and FCG have agreed to exchange 4,130,530
shares of common stock of Holdco (the "Common Shares") to be received by FCG in
the Second Step Merger in exchange for the Old HQ Common Stock to be purchased
by FCG from CarrAmerica and certain other persons pursuant to the Stock Purchase
Agreement for 3,704,933.820 newly issued shares of Series A Convertible
Cumulative Preferred Stock (the "Preferred Stock") of Holdco and warrants to
purchase up to 1,660,341.752 shares of voting common stock, par value $.01 per
share (the "Voting Common Stock"), of Holdco, the terms of which are in the form
attached as Exhibit B hereto in respect of warrants to purchase 1,119,660.807
shares of Voting Common Stock (the "Initial Total FCG Warrants") and in Exhibit
C hereto in respect of warrants to purchase 540,680.945 shares of Voting Common
Stock (the "Subsequent Total FCG Warrants").

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         WHEREAS, upon consummation of the transactions contemplated in the
Exchange Agreement, FCG desires to sell to the Investor, and the Investor
desires to purchase from FCG, certain securities on the terms and conditions
specified in this Agreement.

         WHEREAS, Holdco desires to sell to the Investor, and the Investor
desires to purchase from Holdco, certain securities on the terms and conditions
specified in this Agreement.

         WHEREAS, capitalized words and phrases used but not otherwise defined
herein shall have the meanings ascribed to them under the Merger Agreement.

         Accordingly, Holdco, FCG and the Investor hereby agree as follows:

         1. Purchase and Sale of Securities. (a) On the terms and subject to the
conditions of this Agreement, (i) Holdco agrees to sell to the Investor, and the
Investor agrees to purchase from Holdco, for $43,942,374.85 (the "Holdco
Purchase Price") (A) the 1,077,758.180 newly issued shares of Preferred Stock
(the "Holdco Preferred Shares"), the terms of which are contained in the
certificate of designations to Holdco's certificate of incorporation (the
"Certificate of Designations") in the form attached as Exhibit A hereto, having
an initial liquidation preference equal to $43,942,374.85 and (B) warrants to
purchase up to 482,990.248 shares of Voting Common Stock (the "Holdco Warrants,"
and together with the Holdco Preferred Shares, the "Holdco Securities"), the
terms of which are in the form attached as Exhibit B hereto in respect of Holdco
Warrants to purchase 325,707.193 shares of Voting Common Stock (the "Initial
Holdco Warrants", and together with the Initial Total FCG Warrants, the "Initial
Warrants") and in Exhibit C hereto in respect of Holdco Warrants to purchase
157,283.055 shares of Voting Common Stock (the "Subsequent Holdco Warrants", and
together with the Subsequent Total FCG Warrants, the "Subsequent Warrants").

                  (b) On the terms and subject to the conditions of this
Agreement, (i) FCG agrees to sell to the Investor, and the Investor agrees to
purchase from FCG, for $31,057,625.15 (the "FCG Purchase Price") (A) 761,738.748
shares of Preferred Stock purchased by FCG from Holdco pursuant to the Exchange
Agreement (the "FCG Preferred Shares"), the terms of which are contained in the
Certificate of Designations in the form attached as Exhibit A hereto, having an
initial liquidation preference equal to $31,057,625.15 and (B) warrants to
purchase up to 341,368.213 shares of Voting Common Stock purchased by FCG from
Holdco pursuant to the Exchange Agreement (the "FCG Warrants," and together with
the FCG Preferred Shares, the "FCG Securities"), the terms of which are in the
form attached as Exhibit B hereto in respect of FCG Warrants to purchase
230,203.576 shares of Voting Common Stock and in Exhibit C hereto in respect of
FCG Warrants to purchase 111,164.637 shares of Voting Common Stock.

                  (c) The closing (the "Closing") of the purchase and sale of
the securities referred to in clause (a) above shall be held at the offices of
Brown & Wood LLP, One World Trade Center, New York, New York 10048, immediately
after, and on the same date as, the

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Closing under the Merger Agreement, subject to the satisfaction or waiver of the
conditions set forth in Section 6 hereof. The date on which the Closing shall
occur, which shall not extend beyond June 5, 2000, is hereinafter referred to as
the "Closing Date," and, if the Closing Date is not May 31, 2000, Holdco and FCG
shall notify the Investor prior to the close of business on the business day
immediately preceding the Closing Date. On the Closing Date, (i) Holdco shall
deliver certificates issued in the Investor's name representing the Holdco
Preferred Shares and the Holdco Warrants, (ii) FCG shall deliver certificates
issued in the Investor's name representing the FCG Preferred Shares and the FCG
Warrants, and (iii) the Investor shall deposit the Holdco Purchase Price and the
FCG Purchase Price in immediately available funds with Citibank, N.A., as escrow
agent (the "Escrow Agent") under the Escrow Agreement, dated as of May 31, 2000
(the "Escrow Agreement") for payment to Holdco and FCG, respectively, it being
understood that the Closing shall occur, and the Holdco Purchase Price and the
FCG Purchase Price only released from escrow, in accordance with the terms and
conditions set forth in the Escrow Agreement.

         2. Representations and Warranties of Holdco. Holdco hereby represents
and warrants to the Investor as of the date hereof and as of the Closing Date
that the representations and warranties applicable to Old HQ and VANTAS
contained in Sections 4(A) and 5(A), respectively, of the Merger Agreement are
true and correct with the same force and effect as though made at and as of the
date hereof. In addition, Holdco represents and warrants to the Investor as of
the date hereof and as of the Closing Date as to the following matters:

                  (a) Organization and Standing. Holdco is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware. Holdco and its subsidiaries have all requisite corporate power and
authority necessary to carry on their respective businesses as presently
conducted and to enable them to own, lease or otherwise hold their respective
properties and assets. Holdco and its subsidiaries are duly qualified to do
business and in good standing in each jurisdiction in which the conduct or
nature of their respective businesses or the ownership, leasing or holding of
their respective properties or assets makes such qualification necessary, except
any such jurisdiction where the failure to be so qualified or in good standing,
individually or in the aggregate, would not have a material adverse effect on
the business, financial condition or results of operations of Holdco and its
subsidiaries taken as a whole (a "Holdco Material Adverse Effect").

                  (b) Authority. Holdco has all requisite corporate power and
authority to enter into this Agreement, the Exchange Agreement, that certain
Registration Rights Agreement, in the form attached as Exhibit D hereto (the
"Registration Rights Agreement"), and the Stockholders Agreement, in the form
attached as Exhibit E hereto (the "Stockholders Agreement"), to perform its
obligations hereunder and thereunder and to consummate the transactions
contemplated hereby and thereby. All corporate acts and other proceedings
required to be taken by Holdco to authorize the execution, delivery and
performance of this Agreement, the Exchange Agreement, the Registration Rights
Agreement and the Stockholders Agreement and the consummation of the
transactions contemplated hereby and thereby have been duly and properly taken.
This Agreement and the Exchange Agreement have each been, and, at the Closing,
the Registration

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Rights Agreement and the Stockholders Agreement will have each been, duly
executed and delivered by Holdco and each constitutes or will constitute, as
applicable, a legal, valid and binding agreement of Holdco, enforceable against
Holdco in accordance with its terms, except insofar as enforcement thereof may
be limited by bankruptcy, insolvency, or other laws relating to or affecting
enforcement of creditors' rights generally or by general equitable principles.

                  (c) No Conflicts; Consents. The execution and delivery of this
Agreement, the Exchange Agreement, the Registration Rights Agreement and the
Stockholders Agreement by Holdco does not, and the consummation of the
transactions contemplated hereby and thereby and compliance with the terms
hereof and thereof will not conflict with, or result in any violation of, or
default (with or without notice or lapse of time, or both) under, or give rise
to a right of termination, cancellation or acceleration of any obligation or to
a material loss of a benefit under, or result in the creation of any lien,
charge or encumbrance of any kind upon any of the properties or assets of Holdco
or its subsidiaries under, any provision of (i) the certificate of incorporation
or by-laws of Holdco and its subsidiaries, (ii) any note, bond, mortgage,
indenture, deed of trust, license, lease, contract, commitment, agreement or
arrangement to which Holdco or any of its subsidiaries is a party or by which
any of them or any of their respective properties or assets is bound or (iii)
subject to the governmental filings and other matters referred to in the
succeeding sentence, any judgment, order or decree, or statute, law, ordinance,
rule or regulation, applicable to Holdco or any of its subsidiaries or any of
their respective properties or assets. Except as set forth on Schedule 2(c), no
consent, approval, license, permit, order or authorization of, or registration,
declaration or filing with, any Governmental Entity is required to be obtained
or made by or with respect to Holdco or any of its subsidiaries in connection
with the execution, delivery and performance by Holdco of this Agreement, the
Exchange Agreement, the Registration Rights Agreement and the Stockholders
Agreement or the consummation of the transactions contemplated hereby and
thereby, other than such other consents, approvals, orders, authorizations,
registrations, declarations and filings (i) as are set forth on Schedule 2(c),
(ii) as may be required under the "blue sky" laws of various states and (iii) as
otherwise contemplated in the Registration Rights Agreement.

                  (d) Capital Stock. The authorized capital stock of Holdco
consists of 75,000,000 shares of Voting Common Stock, 25,000,000 shares of
non-voting common stock, par value $.01 per share (the "Nonvoting Common Stock,"
and together with the Voting Common Stock, the "Common Stock"), and 7,800,000
shares of preferred stock. At the Closing, there shall only be 9,972,827 shares
of Voting Common Stock, 2,152,988 shares of Nonvoting Common Stock and 4,782,692
Preferred Shares issued and outstanding. All of the outstanding shares of Common
Stock have been, and at the Closing, all of the shares of Common Stock issued
pursuant to the Second Step Merger Agreement will be, validly issued and
outstanding, fully paid and nonassessable. At the Closing, (i) the Initial
Warrants entitle the holders thereof to purchase 1,445,368 shares of the Common
Stock of Holdco, representing 7.875% of the shares of Common Stock of Holdco on
a fully diluted basis, and (ii) the Subsequent Warrants will entitle the holders
thereof to purchase 697,964 shares of the Common Stock of Holdco, representing
3.375% of the shares of Common Stock of Holdco on a fully-diluted basis. Except
as set forth in Schedule 2(d), none of the outstanding shares of Common Stock
have been issued in violation

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of, or are subject to, any preemptive or similar rights under any provision of
applicable law, the certificate of incorporation or by-laws of Holdco or any
agreement, contract or instrument to which Holdco is a party or by which it or
any of its properties or assets is bound. Except as set forth on Schedule 2(d),
there are no outstanding warrants, options, rights, convertible or exchangeable
securities or other commitments (other than those contemplated by this
Agreement) (i) pursuant to which Holdco is or may become obligated to issue,
sell, purchase, return or redeem any shares of Common Stock or its preferred
stock or (ii) that give any person the right to receive any benefits or rights
similar to any rights enjoyed by or accruing to the holders of shares of Common
Stock or its preferred stock of Holdco. There are no shares of Common Stock or
preferred stock reserved for issuance by Holdco for any purpose except for
securities reserved for issuance for the purposes set forth on Schedule 2(d).
Except as set forth in Schedule 2(d), there are no outstanding bonds,
debentures, notes or other indebtedness having the right to vote on any matters
on which stockholders of Holdco may vote.

                  (e) Preferred Shares. The Holdco Preferred Shares and the FCG
Preferred Shares have been duly authorized for issuance by Holdco pursuant to
the terms of this Agreement and, at Closing, (i) will be validly issued, fully
paid and nonassessable, (ii) will be free and clear of all Liens, other than
transfer restrictions relating to the federal securities laws, (iii) will not be
issued in violation of any preemptive or similar rights under any provisions of
applicable law, the certificate of incorporation or by-laws of Holdco or any
agreement, contract or instrument to which Holdco is a party or by which it or
any of its properties or assets is bound and (iv) assuming the accuracy of the
representations and warranties set forth in Section 4 will be issued in
compliance with the registration and qualification requirements of all
applicable federal securities laws as presently in effect.

                  (f) Warrants. The Holdco Warrants and the FCG Warrants have
been duly authorized for issuance by Holdco pursuant to the terms of this
Agreement and, at Closing, will be legal, valid and binding obligations of
Holdco, enforceable against Holdco in accordance with their terms, except
insofar as enforcement thereof may be limited by bankruptcy, insolvency or other
laws relating to or affecting enforcement of creditors' rights generally or by
general equity principles.

                  (g) Common Stock. The shares of Common Stock issuable upon
conversion of the Holdco Preferred Shares and FCG Preferred Shares or upon
exercise of the Holdco Warrants or FCG Warrants have been duly authorized by
Holdco and, when issued and delivered in accordance with the terms of the Holdco
Preferred Shares, FCG Preferred Shares, Holdco Warrants or FCG Warrants, as the
case may be, will be validly issued, fully paid and nonassessable and will not
be subject to any preemptive or similar rights under any provision of applicable
law, the certificate of incorporation or by-laws of Holdco or any agreement,
contract or instrument to which Holdco is a party or by which it or any of its
properties or assets is bound.

                  (h) Financial Statements. (i) The audited consolidated balance
sheets of VANTAS as of June 30, 1997, June 30, 1998, December 31, 1998 and
December 31, 1999 and the related consolidated statements of income,
stockholder's equity and cash flows of

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VANTAS for the fiscal years ended as of such dates, which financial statements
have been examined by PricewaterhouseCoopers LLP, independent certified public
accountants, (ii) the unaudited consolidated balance sheet of VANTAS as of March
31, 2000 and related consolidated statements of income, stockholder's equity and
cash flows of VANTAS for the fiscal quarter ended as of such date, (iii) the
audited consolidated balance sheets of Old HQ as of December 31, 1997, December
31, 1998 and December 31, 1999 and the related statements of earnings and cash
flows of Old HQ and its subsidiaries for the fiscal years ended as of such
dates, which financial statements have been examined by KPMG LLP, independent
certified public accountants, (iv) the unaudited consolidated balance sheet of
Old HQ as of March 31, 2000 and the related statements of earnings and cash
flows of Old HQ and its subsidiaries for the fiscal quarter ended as of such
date, and (v) the pro forma (after giving effect to the consummation of the HQ
Merger, the Second Step Merger and related financing and other related matters)
consolidated balance sheets and statements of income and cash flows of Holdco
and its subsidiaries as of December 31, 1999, copies of all of which financial
statements referred to in the preceding clauses (i), (ii), (iii), (iv) and (v)
have heretofore been made available to the Investor, present fairly the
financial position of the respective entities at the dates of said statements
and the results of operations for the period covered thereby (or, in the case of
the pro forma financial statements, present a good faith estimate of the pro
forma financial condition of Holdco and its subsidiaries (after giving effect to
the consummation of the HQ Merger, the Second Step Merger and related financing
and other related matters) on a consolidated basis at the date thereof). All
such financial statements have been prepared in accordance with generally
accepted accounting principles consistently applied except to the extent
provided in the notes to said financial statements and with respect to interim
financial statements, subject to normal year end adjustments.

         3. Representations and Warranties of FCG. FCG hereby represents and
warrants to the Investor as of the date hereof and as of the Closing Date as to
the following matters:

                  (a) Organization and Standing. FCG is a corporation duly
organized, validly existing and in good standing as a corporation under the laws
of the State of Delaware. FCG and its subsidiaries have all requisite corporate
power and authority necessary to carry on their respective businesses as
presently conducted and to enable them to own, lease or otherwise hold their
respective properties and assets. FCG and its subsidiaries are duly qualified to
do business and in good standing in each jurisdiction in which the conduct or
nature of their respective businesses or the ownership, leasing or holding of
their respective properties or assets makes such qualification necessary, except
any such jurisdiction where the failure to be so qualified or in good standing,
individually or in the aggregate, would not have a material adverse effect on
the business, financial condition or results of operations of Holdco and its
subsidiaries taken as a whole (an "FCG Material Adverse Effect").

                  (b) Authority. FCG has all requisite corporate power and
authority to enter into this Agreement, to perform its obligations hereunder and
to consummate the transactions contemplated hereby. All corporate acts and other
proceedings required to be taken by FCG to authorize the execution, delivery and
performance of this Agreement and the consummation of

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the transactions contemplated hereby have been duly and properly taken. This
Agreement has been duly executed and delivered by FCG and constitutes a legal,
valid and binding agreement of FCG, enforceable against FCG in accordance with
its terms, except insofar as enforcement thereof may be limited by bankruptcy,
insolvency, or other laws relating to or affecting enforcement of creditors'
rights generally or by general equitable principles.

                  (c) FCG Preferred Shares and FCG Warrants. On the Closing
Date, FCG will be the sole record and beneficial owner and holder of the FCG
Preferred Shares and the FCG Warrants, free and clear of all claims, conditional
sale or other title retention agreements, covenants, encumbrances, equitable
interests, liens, options, pledges, rights of first refusal, security interests,
statutory liens or restrictions of any kind, including any restrictions on
voting, transfer, receipt of income, or exercise of any other attribute of
ownership ("Liens"). At the Closing, FCG will transfer to the Investor good and
marketable title to the FCG Preferred Shares and the FCG Warrants, free and
clear of all Liens. Except as contemplated in Section 3(d), at the Closing, no
legend or other reference to any purported Lien will appear upon any certificate
representing the FCG Preferred Shares or the FCG Warrants. At the Closing, none
of the FCG Preferred Shares or the FCG Warrants will be transferred to FCG in
violation of (i) the Securities Act, the securities laws of any state, or any
other federal, state, local, municipal, foreign, international, multinational,
or other constitution, law, rule, standard, requirement, administrative ruling,
order, ordinance, principle of common law, legal doctrine, code, regulation,
statute, treaty or process or (ii) any award, decision, injunction, judgment,
decree, settlement, order, process, ruling, subpoena or verdict (whether
temporary, preliminary or permanent) entered, issued, made or rendered by any
court, administrative agency, arbitrator, Governmental Entity or other tribunal
of competent jurisdiction.

                  (d) No Conflicts; Consents. The execution and delivery of this
Agreement by FCG does not, and the consummation of the transactions contemplated
hereby and compliance with the terms hereof will not conflict with, or result in
any violation of, or default (with or without notice or lapse of time, or both)
under, or give rise to a right of termination, cancellation or acceleration of
any obligation or to a material loss of a benefit under, or result in the
creation of any lien, charge or encumbrance of any kind upon any of the
properties or assets of FCG or its subsidiaries under, any provision of (i) the
certificate of incorporation or by-laws of FCG and its subsidiaries, (ii) any
note, bond, mortgage, indenture, deed of trust, license, lease, contract,
commitment, agreement or arrangement to which FCG or any of its subsidiaries is
a party or by which any of them or any of their respective properties or assets
is bound or (iii) subject to the governmental filings and other matters referred
to in the succeeding sentence, any judgment, order or decree, or statute, law,
ordinance, rule or regulation, applicable to FCG or any of its subsidiaries or
any of their respective properties or assets. Except for disclosure in any
reports required pursuant to the Securities Exchange Act of 1934, as amended
(the "Exchange Act"), no consent, approval, license, permit, order or
authorization of, or registration, declaration or filing with, any Governmental
Entity is required to be obtained or made by or with respect to FCG or any of
its subsidiaries in connection with the execution, delivery and performance by
Holdco of this Agreement or the consummation of the transactions contemplated
hereby.

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         4. Representations and Warranties of the Investor. The Investor hereby
represents and warrants to Holdco and FCG as follows:

                  (a) Organization and Standing. The Investor is a limited
partnership duly established, validly existing and in good standing under the
laws of the State of Delaware. The Investor and its subsidiaries have all
requisite partnership or other power and authority necessary to carry on their
respective businesses as presently conducted and to enable them to own, lease or
otherwise hold their respective properties and assets. The Investor and its
subsidiaries are duly qualified to do business and are in good standing in each
jurisdiction in which the conduct or nature of their respective businesses or
the ownership, leasing or holding of their respective properties or assets makes
such qualification necessary, except any such jurisdiction where the failure to
be so qualified or in good standing, individually or in the aggregate, would not
have a material adverse effect on the business, financial condition or results
of operations of the Investor and its subsidiaries taken as a whole (an
"Investor Material Adverse Effect").

                  (b) Authority. The Investor has all requisite partnership
power and authority to enter into this Agreement, the Registration Rights
Agreement and the Stockholders Agreement, to perform its obligations hereunder
and thereunder and to consummate the transactions contemplated hereby and
thereby. All partnership and other acts and other proceedings required to be
taken by the Investor to authorize the execution, delivery and performance of
this Agreement, the Registration Rights Agreement and the Stockholders Agreement
and the consummation of the transactions contemplated hereby and thereby have
been duly and properly taken. This Agreement has been, and, at the Closing, the
Registration Rights Agreement and the Stockholders Agreement will have each
been, duly executed and delivered by the Investor and each constitutes or will
constitute, as applicable, a legal, valid and binding obligation of the
Investor, enforceable against the Investor in accordance with its terms, except
insofar as enforcement thereof may be limited by bankruptcy, insolvency or other
laws relating to or affecting enforcement of creditors' rights generally or by
general equity principles.

                  (c) No Conflicts; Consents. The execution and delivery of this
Agreement, the Registration Rights Agreement and the Stockholders Agreement by
the Investor does not, and the consummation of the transactions contemplated
hereby and thereby and compliance by the Investor with the terms hereof and
thereof will not, conflict with, or result in any violation of or default (with
or without notice or lapse of time, or both) under, or give rise to a right of
termination, cancellation or acceleration of any obligation or to loss of a
material benefit under, or result in the creation of any lien, charge or
encumbrance of any kind upon any of the properties or assets of the Investor or
its subsidiaries under, any provision of (i) the declaration of trust,
partnership agreement, certificate of limited partnership, limited liability
company agreement, charter or by-laws of the Investor and its subsidiaries, (ii)
any note, bond, mortgage, indenture, deed of trust, loan document, license,
lease, contract, commitment, agreement or arrangement to which the Investor or
any of its subsidiaries is a party or by which any of them or any of their
respective properties or assets is bound or (iii) any judgment, order or decree,
or statute, law, ordinance, rule or regulation, applicable to the Investor or
any of its subsidiaries or any of their respective properties or assets. Except
for disclosure in any reports required

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pursuant to the Exchange Act, no consent, approval, license, permit, order or
authorization of, or registration, declaration or filing with, any Governmental
Entity is required to be obtained or made by or with respect to the Investor in
connection with the execution, delivery and performance of this Agreement, the
Registration Rights Agreement and the Stockholders Agreement by the Investor or
the consummation of the transactions contemplated hereby and thereby.

                  (d) Investment Representation. The Investor is purchasing
Holdco Preferred Shares, FCG Preferred Shares, Holdco Warrants and FCG Warrants
pursuant to this Agreement for its own account for investment only and not with
a view towards their distribution or resale. The Investor represents that it is
an "accredited" investor within the meaning of Rule 501 promulgated under the
Securities Act of 1933, as amended (the "Securities Act"), has such knowledge
and experience in financial and business matters that enable it to evaluate the
merits and risks of investment in the Holdco Preferred Shares, FCG Preferred
Shares, Holdco Warrants and FCG Warrants, is able to bear the economic risk of a
loss of its entire investment therein and is prepared to hold the same for an
indefinite period of time. The Investor has received the opportunity to ask
questions, and has obtained the related answers, regarding the business,
financial condition and results of operations of Holdco, VANTAS and Old HQ and
the terms and conditions of the Holdco Preferred Shares, FCG Preferred Shares,
Holdco Warrants and the FCG Warrants. The Investor has received all of the
information regarding Holdco, VANTAS and Old HQ that it has requested. Holdco
and FCG have informed the Investor that the Holdco Preferred Shares, FCG
Preferred Shares, Holdco Warrants and FCG Warrants have not been registered
under the Securities Act and may not be sold, transferred or otherwise assigned
absent such registration or an exemption therefrom. Holdco and FCG have also
informed the Investor that any routine sale of Holdco Preferred Shares, FCG
Preferred Shares, Holdco Warrants and FCG Warrants made in reliance upon Rule
144 promulgated under the Securities Act can be made only in accordance with the
terms and conditions of such Rule and, further, that in case such Rule is not
applicable to any sale of Holdco Preferred Shares, FCG Preferred Shares, Holdco
Warrants and FCG Warrants, as applicable, resale thereof may require compliance
with some other exemption under the Securities Act prior to resale. Holdco and
FCG have informed the Investor that certificates representing the Holdco
Preferred Shares, FCG Preferred Shares, Holdco Warrants and FCG Warrants issued
pursuant to this Agreement bear the following legend:

         "THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
1933, AS AMENDED. SUCH SECURITIES MAY NOT BE SOLD OR OFFERED FOR SALE,
TRANSFERRED OR OTHERWISE ASSIGNED IN THE ABSENCE OF AN EFFECTIVE REGISTRATION
STATEMENT WITH RESPECT THERETO UNDER SUCH ACT OR AN EXEMPTION FROM REGISTRATION
FOR SUCH SALE, OFFER, TRANSFER OR OTHER ASSIGNMENT AS SUPPORTED BY SUCH
CERTIFICATIONS, OPINIONS AND OTHER DOCUMENTATION, IF ANY, REASONABLY REQUESTED
AND ACCEPTABLE TO THE CORPORATION."

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         5. Covenants.

                  (a) Transfer of Rights. At the Closing, FCG shall transfer,
assign and convey to the Investor any and all rights to which FCG is entitled
under the Exchange Agreement and in respect of the FCG Preferred Shares and the
FCG Warrants, all as set forth in the Assignment Agreement attached as Exhibit F
hereto.

                  (b) Consummation of the Transactions. Subject to the terms and
conditions of this Agreement, each party shall use its commercially reasonable
efforts to cause the Closing to occur upon the terms and conditions set forth
herein. Holdco and FCG shall cooperate with the Investor, and the Investor shall
cooperate with Holdco and FCG, in filing any necessary applications, reports or
other documents with, giving any notices to, and seeking any consents from, all
Governmental Entities and all third parties as may be required in connection
with the consummation of the transactions contemplated by this Agreement, and
each party requesting such cooperation shall reimburse the other party's
reasonable out-of-pocket expenses in providing such cooperation.

                  (c) Lock-Up. In connection with an initial public offering of
Holdco's securities, the Investor agrees, and the Investor shall secure the
agreement of any transferee therefrom, upon request of the lead underwriter, not
to sell or otherwise transfer or dispose of any Common Stock of Holdco (other
than to an affiliate of the Investor or another holder of Preferred Stock) for a
period following the effective date of a registration statement of Holdco filed
under the Securities Act with respect to such offering equal to the lesser of
(i) the lock-up period applicable to (a) FCG, (b) CarrAmerica (so long as it
owns in excess of 9% of the outstanding shares of Common Stock), (c) holders of
Preferred Stock, and (d) senior executive officers of Holdco and (ii) six (6)
months.

         6. Conditions to Closing.

                  (a) Each Party's Obligation. The respective obligations of
each party hereto to effect the transactions contemplated by this Agreement are
subject to the satisfaction (or waiver) as of the Closing of the following
conditions: (i) the HQ Merger and the Second Step Merger shall have been
consummated; (ii) no statute, rule, regulation, executive order, decree,
temporary restraining order, preliminary or permanent injunction or other order
shall have been enacted, entered, promulgated, enforced or issued by any
Governmental Entity that prohibits the performance of this Agreement or the
consummation of the transactions contemplated by this Agreement; and (iii) no
action, claim, proceeding or investigation shall be pending or threatened by any
Governmental Entity (other than a court acting in response to an action, claim
or proceeding brought by a non-Governmental Entity) that, if successful, would
prohibit the performance of this Agreement or the consummation of the
transactions contemplated by this Agreement.

                  (b) Obligation of Holdco and FCG. The obligations of Holdco
and FCG hereunder are subject to the satisfaction (or waiver by Holdco or FCG,
as the case may be) as of the Closing of the following conditions:

                                       10
<PAGE>   11

                           (i) The representations and warranties of the
Investor made in this Agreement shall be true and correct as of the date hereof
and as of the time of the Closing as though made as of such time, except (1) to
the extent such representations and warranties expressly relate to an earlier
date (in which case such representations and warranties shall be true and
correct on and as of such earlier date) or (2) where the failure of any
representations and warranties other than the representation and warranty set
forth in Section 4(d) to be true and correct would not have the Investor
Material Adverse Effect, and the Investor shall have duly performed, complied
with and satisfied in all material respects all covenants, agreements and
conditions required by this Agreement to be performed, complied with or
satisfied by the Investor by the time of Closing. At the Closing, the Investor
shall have delivered to Holdco and FCG a certificate, dated the Closing Date and
signed by an officer of the Investor, confirming the foregoing.

                           (ii) At the Closing, the Investor shall have
delivered to Holdco and FCG a secretary's certificate, dated the Closing Date,
attesting to the authorization of the Investor to consummate the transactions
contemplated by this Agreement.

                           (iii) All filings, registrations, authorizations,
permits, consents and approvals required for the Investor's consummation of the
transactions contemplated by this Agreement shall have been made or obtained, as
applicable.

                           (iv) At the Closing, the Investor shall have executed
and delivered to Holdco the Stockholders Agreement and the Registration Rights
Agreement and (assuming due execution and delivery by the other parties thereto)
the same shall be in full force and effect.

                           (v) At the Closing, the Investor shall have deposited
the Holdco Purchase Price and the FCG Purchase Price in immediately available
funds with the Escrow Agent.

                  (c) Investor's Obligation. The obligations of the Investor
hereunder are subject to the satisfaction (or waiver by the Investor) as of the
Closing of the following conditions:

                           (i) The representations and warranties of Holdco made
in this Agreement shall be true and correct as of the date hereof and as of the
time of the Closing as though made as of such time, except (1) to the extent
such representations and warranties expressly relate to an earlier date (in
which case such representations and warranties shall be true and correct on and
as of such earlier date), (2) where the failure of any representations and
warranties other than the representations and warranties set forth in Sections
2(d), (e), (f) or (g) to be true and correct would not have a Holdco Material
Adverse Effect, or (3) that the representation and warranty set forth in Section
2(d) shall be true and correct other than in any de minimis respect, and Holdco
shall have duly performed, complied with and satisfied in all material respects
all covenants, agreements and conditions required by this Agreement to be
performed, complied with or satisfied by Holdco by the time of Closing. At the
Closing, Holdco shall have delivered to the Investor a certificate, dated the
Closing Date and signed by an officer of Holdco, confirming the foregoing.

                                       11
<PAGE>   12

                           (ii) The representations and warranties of FCG made
in this Agreement shall be true and correct as of the date hereof and as of the
time of the Closing as though made as of such time, except (1) to the extent
such representations and warranties expressly relate to an earlier date (in
which case such representations and warranties shall be true and correct on and
as of such earlier date) or (2) where the failure of any representations and
warranties other than the representation and warranty set forth in Section 3(c)
to be true and correct would not have a FCG Material Adverse Effect, and FCG
shall have duly performed, complied with and satisfied in all material respects
all covenants, agreements and conditions required by this Agreement to be
performed, complied with or satisfied by FCG by the time of Closing. At the
Closing, FCG shall have delivered to the Investor a certificate, dated the
Closing Date and signed by an officer of FCG, confirming the foregoing.

                           (iii) At the Closing, each of Holdco and FCG shall
have delivered to the Investor a secretary's certificate, dated the Closing
Date, attesting to its authorization to consummate the transactions contemplated
by this Agreement.

                           (iv) Since the date of this Agreement, Holdco and its
subsidiaries taken as a whole shall not have suffered a Holdco Material Adverse
Effect.

                           (v) All filings, registrations, authorizations,
permits, consents and approvals required for Holdco's and FCG's consummation of
the transactions contemplated by this Agreement shall have been made or
obtained, as applicable.

                           (vi) At the Closing, Holdco shall have executed and
delivered to the Investor the Stockholders Agreement and the Registration Rights
Agreement and (assuming due execution and delivery by the other parties thereto)
the same shall be in full force and effect.

                           (vii) At the Closing, FCG shall have executed and
delivered to the Investor the Assignment Agreement in the form of Exhibit F
hereto and (assuming due execution and delivery by the Investor) the same shall
be in full force and effect.

                           (viii) At or prior to the Closing, Holdco or Old HQ
shall have received debt financing the terms of which are substantially to the
effect set forth in the commitment letter of Paribas attached as Exhibit G
hereto in respect of the bank term debt and either the commitment letter of
Blackstone attached as Exhibit H hereto in respect of the high yield or
mezzanine debt or the commitment letter of Warburg Dillon Read LLC attached as
Exhibit I hereto in respect of bridge financing, whether such financing is
obtained from such parties or any other party, and, at the Closing, except as
disclosed in Schedule 5(c), no other indebtedness of Holdco for borrowed money
shall be outstanding.

                           (ix) At or prior to Closing, the Certificate of
Designations in the form of Exhibit J hereto shall have been accepted for filing
by, and duly filed with, the Secretary of State of the State of Delaware.

                                       12
<PAGE>   13

                           (x) At the Closing, the Investor shall have received
the favorable opinion, dated the Closing Date, of Brown & Wood LLP, counsel to
Holdco and FCG, substantially in the form attached as Exhibit K hereto.

                           (xi) At the Closing, the Investor shall have received
an agreed upon procedures letter, dated the Closing Date, from Ernst & Young
LLP, substantially in the form attached as Exhibit L hereto.

                           (xii) At the Closing, none of the Merger Agreement,
the Second Step Merger Agreement and the UK Stock Purchase Agreement shall have
been amended in any material respect other than an extension of the Closing of
the transactions contemplated thereunder until June 5, 2000, and the conditions
specified in the Merger Agreement, the Second Step Merger Agreement and the UK
Stock Purchase Agreement shall have been satisfied in all material respects, and
there shall have been no waivers to such conditions in any material respect.

                           (xiii) At the Closing, Old HQ shall have executed and
delivered to the Investor the Operating Agreement of HQ Global Workplaces Equity
Joint Venture, LLC, in the form attached as Exhibit M hereto, together with all
of the documents to be executed and delivered by Old HQ pursuant thereto, and
(assuming due execution and delivery by the Investor) the same shall be in full
force and effect.

                           (xiv) At the Closing, one or more parties, other than
FCG or any affiliate thereof or the Investor, shall purchase at least $95
million of Preferred Stock.

                           (xv) At the Closing, Holdco shall have delivered the
Holdco Preferred Shares and Holdco Warrants, and FCG shall have delivered the
FCG Preferred Shares and FCG Warrants, to the Investor.

                  (d) Frustration of Closing Conditions. Neither FCG nor the
Investor may rely on the failure of any condition set forth in Sections 6(a),
(b), (c) or (d), respectively, to be satisfied if such failure was caused by
such party's failure to perform its obligations hereunder or to use its
commercially reasonable efforts to cause the Closing to occur as required by
Section 6.

         7. Further Assurances. From time to time, as and when requested by
another party hereto, a party hereto shall execute and deliver, or cause to be
executed and delivered, all such documents and instruments and shall take, or
cause to be taken, all such further or other actions as such other party may
reasonably deem necessary or desirable to consummate the transactions
contemplated by this Agreement.

         8. Assignment. This Agreement and the rights and obligations hereunder
shall not be assignable or transferable by (i) FCG or Holdco without the prior
written consent of the Investor or (ii) by the Investor without the prior
written consent of Holdco and FCG. Any attempted assignment in violation of this
Section 8 shall be void ab initio and of no further force and effect.

                                       13
<PAGE>   14

         9. No Third-Party Beneficiaries. This Agreement is for the sole benefit
of the parties hereto and their successors and permitted assigns, and nothing
herein expressed or implied shall give or be construed to give to any person,
other than the parties hereto and such permitted successors and assigns, any
legal or equitable rights hereunder.

         10. Amendments. No amendment, modification or waiver in respect of this
Agreement shall be effective unless it shall be in writing and signed by the
party against whom such amendment, modification or waiver is asserted.

         11. Representations, Warranties and Agreements to Survive Delivery. All
representations, warranties and agreements contained in this Agreement or in
certificates of officers of FCG or the Investor submitted pursuant hereto shall
remain operative and in full force and effect for a period of one year (or, in
the case of the representation and warranty specified in Section 5(A)(b) of the
Merger Agreement, for the period of any applicable statute of limitations)
following the Closing. Notwithstanding anything to the contrary contained in the
foregoing, nothing in this Section 11 is intended to indicate that any
representation or warranty will be true at any time other than at the time of
execution of this Agreement and at the Closing.

         12. Indemnification.

                  (a) Indemnity by Holdco and FCG. Holdco and FCG shall, jointly
and severally, indemnify the Investor and its affiliates, controlling persons,
constituent partners and subsidiaries and their directors, officers, members,
employees against all expenses, costs, losses, claims, damages, liabilities and
judgments (including, without limitation, reasonable attorney's fees and
expenses) incurred or sustained by any such party resulting from (i) any breach
of the representations and warranties of Holdco set forth in Section 2 or FCG
set forth in Section 3, (ii) FCG's, Holdco's or VANTAS' acts or failure to act,
(iii) any misstatements or omissions made in any disclosure or other information
or materials delivered or made available to the Investor in connection with the
investment contemplated under this Agreement, (iv) the action or failure to act
by an indemnified party with FCG's, Holdco's or VANTAS' consent or in reliance
on FCG's, Holdco's or VANTAS' action or failure to act or (v) any and all
environmental liabilities, costs and expenses arising out of or incurred in
connection with the consummation of the Merger, the Second Step Merger or the
investment contemplated in this Agreement; provided, however, that such
indemnity shall not extend to any expenses, costs, losses, claims, damages,
liabilities or judgments to the extent arising out of (A) the gross negligence
or willful misconduct of any person indemnified under this Section 12(a) as
determined by a court of competent jurisdiction in a final, non-appealable
judgment or (B) a breach by the Investor of its representations and warranties
contained herein.

         FCG agrees to indemnify the Investor against any Company Level Loss or
Direct Loss (each as defined below) directly or indirectly suffered or incurred
by it arising out of (i) Rule 10b-5 under the Exchange Act with respect to
VANTAS' failure to file reports with the Securities and Exchange Commission as
required under the Exchange Act prior to the date hereof or (ii) the Shareholder
Litigation (as defined in the Form of Indemnification and Escrow Agreement
attached as Exhibit E to the Merger Agreement (the "Indemnification Agreement").

                                       14
<PAGE>   15

FCG shall pay the Investor, in full and complete satisfaction of FCG's
obligation under clause (ii) in this paragraph, an amount (which, in the case of
a Direct Loss, shall not exceed such Direct Loss) equal to the product of (A) a
fraction, the numerator of which equals the sum of the number of shares of
Preferred Stock (determined on an As-Converted Basis) and the number of shares
of Common Stock purchasable upon exercise of the Initial Warrants, in each case
owned by the Investor at the Closing, and the denominator of which equals the
sum of the number of shares of Preferred Stock (determined on an As-Converted
Basis) and the number of shares of Common Stock purchasable upon exercise of the
Initial Warrants, in each case owned by the Investor at the Closing, and the
number of shares of Common Stock owned by FCG at the Closing, multiplied by (B)
the dollar value of any recovery obtained by FCG from CarrAmerica under the
Indemnification Agreement. A "Company Level Loss" shall mean any loss,
liability, claim, damage or expense (including, without limitation, reasonable
attorney's fees and expenses) incurred by Holdco or Old HQ or its successor; it
being understood that a Company Level Loss shall not include (i) any
consequential, incidental or punitive damages or (ii) any Direct Loss; it being
understood that a Company Level Loss shall include any loss or damage suffered
by the Investor as a result of a diminution in value (either directly or
indirectly) of the interest held by the Investor in Holdco. A "Direct Loss"
shall mean any loss, liability, claim, damage or expense (including reasonable
attorney's fees and expenses) incurred by the Investor; it being understood that
a Direct Loss shall not include (i) any consequential, incidental or punitive
damages, (ii) any Company Level Loss or (iii) any loss or damage suffered by the
Investor as a result of a diminution in value (either directly or indirectly) of
the interest held by the Investor in Holdco.

                  (b) Indemnity by the Investor. The Investor shall indemnify
FCG, Holdco and their respective directors, officers and employees against all
expenses, costs, losses, claims, damages, liabilities and judgments (including,
without limitation, reasonable attorney's fees and expenses) incurred or
sustained by any such party resulting from any breach of the representations and
warranties of the Investor set forth in Section 4; provided, however, that such
indemnity shall not extend to any expenses, costs, losses, claims, damages,
liabilities and judgments to the extent arising out of (A) the gross negligence
or willful misconduct of any person indemnified under this Section 12(b) as
determined by a court of competent jurisdiction in a final, non-appealable
judgment or (B) a breach by Holdco or FCG, as the case may be, of the
representations and warranties set forth in Section 2 or Section 3,
respectively. Under no circumstances shall the Investor be liable to FCG, Holdco
or any other indemnified party under this Section 12(b) for any punitive,
exemplary, consequential or indirect damages arising therefrom.

                  (c) Notice of Actions or Proceedings. In case any action or
proceeding shall be commenced involving any party in respect of which indemnity
may be sought pursuant to Sections 12(a) or 12(b) (the "indemnified party"), the
indemnified party shall promptly notify the party against whom such indemnity
may be sought (the "indemnifying party") in writing of such action or
proceeding; provided, however, that failure of an indemnified party to provide
such notice shall not relieve the indemnifying party of its obligations under
this Section 12 if such failure does not materially and adversely affect the
rights of the indemnifying party.

                                       15
<PAGE>   16

                  (d) Defense of Actions and Proceedings. The indemnifying party
may assume the defense of such action or proceeding provided that the expenses
of the indemnified party are reimbursed as they are incurred (including, without
limitation, the payment of all reasonable and documented fees and expenses of
counsel to the indemnified party) and the indemnifying party has not failed to
comply with any such reimbursement request. Any indemnified party shall have the
right to employ separate counsel in any such action or proceeding and
participate in the defense thereof, but the reasonable fees and expenses of such
counsel shall be at the expense of the indemnified party, unless (i) the
employment of such counsel shall have been specifically authorized in writing by
the indemnifying party, (ii) the indemnifying party shall have failed to assume
the defense of such action or proceeding or (iii) the named parties to any such
action (including any impleaded parties) include both the indemnified party and
the indemnifying party, and the indemnified party shall have been reasonably
advised by such counsel that the representation of the indemnifying party and
the indemnified party by the same counsel would be inappropriate due to actual
or potential differing interests between the indemnifying party and the
indemnified party or there are defenses that are available to the indemnified
party that may be in conflict with or contradict those available to the
indemnifying party (in which case the indemnifying party shall not have the
right to assume the defense of such action on behalf of the indemnified party).
In any such case, the indemnifying party shall not, in connection with any one
action or separate but substantially similar or related actions or proceedings
in the same jurisdiction arising out of the same general allegations or
circumstances, be liable for the reasonable fees and expenses of more than one
separate firm of attorneys for all indemnified parties and all such reasonable
fees and expenses shall be reimbursed as they are incurred. The indemnifying
party shall indemnify and hold harmless the indemnified party from and against
any and all expenses, costs, losses, claims, damages, liabilities and judgments
by reason of any settlement made by the indemnified party of any action effected
with the indemnifying party's written consent. The indemnifying party shall not,
without the prior written consent of the indemnified party, effect any
settlement or compromise of, or consent to the entry of judgment with respect
to, any pending or threatened action or proceeding in respect of which the
indemnified party is or could have been a party and indemnity may be or could
have been sought hereunder by the indemnified party, unless (i) such settlement,
compromise or judgment includes an unconditional release of the indemnified
party from all liability on claims that are the subject matter of such action or
proceeding and does not include a statement as to or an admission of fault or
culpability by or on behalf of the indemnified party and (ii) reasonable prior
written notice of settlement, compromise or judgment is given to the indemnified
party.

         13. Notices. All notices or other communications required or permitted
to be given hereunder shall be in writing and shall be delivered by hand or sent
by prepaid telex, cable or telecopy or sent, postage prepaid, by registered,
certified or express mail or reputable overnight courier service and shall be
deemed given when so delivered by hand, telexed, cabled or telecopied, or if
mailed, three days after mailing (one business day in the case of express mail
or overnight courier service), as follows:

                                       16
<PAGE>   17

                  (i)      if to Holdco,

                           15950 North Dallas Parkway
                           Suite 350
                           Dallas, Texas  75248
                           Attention:  General Counsel
                           Tel:  (972) 361-8100
                           Fax:  (972) 361-8216

                   (ii)    if to FCG,

                           FrontLine Capital Group
                           1350 Avenue of the Americas
                           New York, New York.  10019
                           Attention:   Jason M. Barnett, General Counsel
                           Tel:  (212) 931-8000
                           Fax:  (212) 931-8001

                           with copies  to:

                           Brown & Wood llp
                           One World Trade Center
                           New York, New York  10048
                           Attention:  Edward F. Petrosky, Jr., Esq.
                                        J. Gerard Cummins, Esq.
                           Tel:  (212) 839-5300
                           Fax:  (212) 839-5599

                  (iii)    if to the Investor,

                           EOP Operating Limited Partnership
                           Suite 2100
                           Two North Riverside Plaza
                           Chicago, Illinois 60606
                           Attention: Chief Legal Counsel
                           Tel: (312) 466-3362
                           Fax: (312) 559-5021

or such other address as any party may from time to time specify by written
notice to the other parties hereto.

                                       17
<PAGE>   18

         14. Interpretation; Exhibits and Schedules. The headings contained in
this Agreement and in any Exhibit to this Agreement are for reference purposes
only and shall not affect in any way the meaning or interpretation of this
Agreement. All Exhibits annexed hereto or referred to herein are hereby
incorporated in and made a part of this Agreement as if set forth in full
herein. Any capitalized term used in any Exhibit but not otherwise defined
therein shall have the meaning ascribed to it in this Agreement. This Agreement
is gender neutral. Any word in this Agreement that refers to a particular gender
shall also refer to all other genders, including masculine, feminine and neuter.

         15. Counterparts. This Agreement may be executed in one or more
counterparts, all of which shall be considered one and the same agreement, and
shall become effective when one or more such counterparts have been signed by
each of the parties and delivered to the other party.

         16. Entire Agreement. This Agreement contains the entire agreement and
understanding between the parties hereto with respect to the subject matter
hereof and supersedes all prior agreements and understandings relating to such
subject matter, except insofar as it relates to the Break-Up Fee specified in
the Term Sheet, dated April 26, 2000. The parties hereto shall not be liable or
bound to any other party in any manner by any representations, warranties or
covenants relating to such subject matter except as specifically set forth
herein.

         17. Brokers. Each party hereto hereby represents and warrants that no
brokers or finders have acted for such party in connection with this Agreement.

         18. Severability. If any provision of this Agreement (or any portion
thereof) or the application of any such provision (or any portion thereof) to
any person or circumstance shall be held invalid, illegal or unenforceable in
any respect by a court of competent jurisdiction, such invalidity, illegality or
unenforceability shall not affect any other provision hereof (or the remaining
portion thereof) or the application of such provision to any other persons or
circumstances.

         19. Consent to Jurisdiction. The Investor and FCG agree to commence any
action, suit or proceeding arising out of this Agreement or transactions
contemplated hereby against the other party either in a federal court located in
the State of New York or if such suit, action or other proceeding may not be
brought in such court for jurisdictional reasons, in a New York state court.
Each party to this Agreement submits and consents to personal jurisdiction in
any such litigation. The Investor and FCG further agree that service of any
process, summons, notice or document delivered by U.S. registered mail to such
party's respective address set forth above shall be effective service of process
for any action, suit or proceeding in New York with respect to any matters to
which it has submitted to jurisdiction in this Section 18. The Investor and FCG
irrevocably and unconditionally waive any objection to the laying of venue of
any action, suit or proceeding arising out of this Agreement or the transactions
contemplated hereby in (i) any New York state court or (ii) any federal court
located in the State of New York, and hereby further irrevocably and
unconditionally waives and agrees not to plead or claim in any such court that
any such action, suit or proceeding brought in any such court has been brought
in an inconvenient forum. EACH OF THE PARTIES HERETO IRREVOCABLY WAIVES TRIAL BY
JURY IN ANY ACTION OR PROCEEDING WITH RESPECT TO THIS AGREEMENT.

                                       18
<PAGE>   19

         20. Governing Law. This Agreement shall be governed by and construed in
accordance with the internal laws of the State of New York applicable to
agreements made and to be performed entirely within such State, without regard
to the conflicts of law principles of such State.

                                       19
<PAGE>   20

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed as of the date first written above.

                                       FRONTLINE CAPITAL GROUP

                                       By:
                                          ----------------------------------
                                          Name:
                                          Title:

                                       HQ GLOBAL HOLDINGS, INC.

                                       By:
                                          ----------------------------------
                                          Name:
                                          Title:

                                       EOP OPERATING LIMITED PARTNERSHIP
                                       By:  Equity Office Properties Trust,
                                             its managing general partner

                                       By:
                                          ----------------------------------
                                          Name:
                                          Title:

                                       20
<PAGE>   21

                                  SCHEDULE 2(c)

                                     Nothing

<PAGE>   22

                                  SCHEDULE 2(d)

                          CAPITAL STOCK OF THE COMPANY

1.       Section 5 of the Stockholders Agreement, dated as of the date hereof
         (the "CarrAmerica Stockholders Agreement"), by and among FrontLine
         Capital Group, HQ Global Holdings, Inc. and CarrAmerica Realty
         Corporation contains Participation Rights granting CarrAmerica the
         right to purchase its "pro rata share" of any issuance by the Company
         of equity securities (subject to certain qualifications).

2.       Section 5 of the Stockholders Agreement, dated the date hereof, by and
         among FrontLine Capital Group, HQ Global Holdings, Inc. and certain
         holders of Series A Preferred Stock contains Participation Rights
         granting holders of Series A Preferred Stock the right to purchase
         their "pro rata share" of any issuance by the Company of equity
         securities (subject to certain qualifications).

3.       Warrants to purchase 2,143,332 shares of Common Stock (subject to
         antidilution rights), dated the date hereof, issued to holders of
         Series A Preferred Stock.

4.       Warrants to purchase 1,498,538 shares of Common Stock (subject to
         antidilution rights), dated the date hereof, issued to UBS AG Stamford
         Branch.

5.       Warrant Agreement dated as of March 4, 1998 by and between OmniOffices,
         Inc. and Robert A. Arcoro for the purchase of 100,000 shares at $20.00
         per share. Mr. Arcoro has exercised his warrant for 99,000 shares. Only
         1,000 shares remain subject to this agreement.

6.       Warrant Agreement dated as of March 4, 1998 by and between OmniOffices,
         Inc. and Joseph Kaidanow for the purchase of 85,000 shares at $20.00
         per share. Mr. Kaidanow has exercised his warrant for 50,000 shares.
         Only 35,000 shares remain subject to this agreement.

7.       Warrant Agreement dated as of March 4, 1998 by and between OmniOffices,
         Inc. and Kimberly L. Arcoro for the purchase of 32,500 shares at $20.00
         per share.

8.       Warrant Agreement dated as of March 4, 1998 by and between OmniOffices,
         Inc. and Robert A. Arcoro, Jr. for the purchase of 32,500 shares at
         $20.00 per share.

         o        The Company is obligated to have authorized and in reserve the
                  shares of common stock receivable upon exercise of each of the
                  warrants under the Warrant Agreements.

         o        In the event the Company issues non-voting common stock of the
                  Company that is less than fair market value (other than stock
                  options or restricted stock

<PAGE>   23

                  pursuant to stock options plans) the warrantholders are
                  entitled to an adjustment of the warrant shares purchasable
                  under the Warrant.

         o        The Warrant Agreements contain antidilution provisions that
                  are triggered by distributions to holders of equity capital
                  stock (dividends) and the repurchase of common stock by the
                  Company of common stock at a price that is greater than the
                  fair market value of common stock on the date of the
                  repurchase.

9.       Purchase Right Agreement, dated as of March 4, 1998, by and among
         OmniOffices, Inc., Robert A. Arcoro and Joseph Kaidanow pursuant to
         which if immediately prior the first date on which 20% or more of the
         outstanding shares of common stock of the Company have been publicly
         distributed or registered and such shares are publicly traded on a
         national exchange or over-the-counter market, the debt ratio is less
         than 55.0% (the Company is obligated to offer the warrantholders the
         right to purchase up to an aggregate of 6,818 shares of common stock of
         the Company per percentage point below the 55.0% (subject to the
         adjustments set forth in Section 5(a) of the Warrant Agreement). This
         Purchase Right is subject to antidilution protection for the benefit of
         the Company pursuant to Section 10 of the CarrAmerica Stockholders
         Agreement.

10.      [Gary Kusin holds rights to receive 120,000 shares of Class B
         Non-Voting Stock and 300,000 options to acquire Non-Voting Common Stock
         pursuant to his employment contract. These rights accelerate in vesting
         upon a change in control.]

11.      Pursuant to the Merger Agreement, at the effective time of the Merger,
         each outstanding option to purchase shares of VANTAS Common Stock
         granted under the VANTAS 1996 Stock Option Plan (the "VANTAS 1996 Stock
         Options"), is automatically amended to constitute an option to acquire
         the number of shares of Voting Common Stock of the Company as the
         holder of such VANTAS 1996 Stock Option would have been entitled to
         receive as Merger Consideration in the Merger had such holder exercised
         such VANTAS 1996 Stock Option (free of and without regard to any
         limitation on the vesting of the right to exercise such VANTAS 1996
         Stock Option) immediately prior to the effective time of the Merger at
         an exercise price equal to the quotient of (a) the applicable exercise
         price for each such VANTAS 1996 Stock Option immediately prior to the
         effective time of the Merger divided by (b) the Conversion Ratio.

         The following is a list of options granted under the VANTAS 1996 Stock
         Option Plan that are subject to the foregoing:

         o        36,750 Options at an exercise price of $2.00

         o        250 Options at an exercise price of $4.75

         o        40,458 Options at an exercise price of $4.00

                                       2

<PAGE>   24

12.      As soon as practicable following the effective time of the Merger, Mr.
         Gary Kusin and Mr. David Rupert will receive options to purchase common
         stock of the Company with a value equal to 6X and 4X, respectively, of
         their respective Base Compensation, or $3,600,000 or $1,600,000,
         respectively, which will become exercisable over a four-year period
         (37.5% after 18 months, then 12.5% every 6 months up to 100% in total,
         provided in each case that the executive is still employed by the
         Company on the applicable vesting date). The exercise price per share
         will equal the per share valuation used for purposes of the Merger.

13.      As soon as practicable following the effective time of the Merger, Mr.
         Kusin and Mr. Rupert will receive a grant of restricted common stock in
         the Company with a value equal to 2.5X and 1.5X, respectively, of their
         respective Base Compensation, or $1,500,000 or $600,000, respectively,
         which will become vested over a four-year period (37.5% after 18
         months, then 12.5% every 6 months up to 100% in total, provided in each
         case that the executive is still employed by the Company on the
         applicable vesting date).

14.      It is anticipated that options and restricted stock with respect to 3%
         and 1%, respectively, of the outstanding common and preferred stock of
         the Company will be issued in connection with employee incentive
         compensation.

                                       3

<PAGE>   25

                                  SCHEDULE 5(c)

                HQ Global Holdings, Inc: Outstanding Indebtedness
                           Existing Letters of Credit

JP MORGAN LETTERS OF CREDIT

<TABLE>
<CAPTION>
  LC#                      Letter of Credits Issued     Beneficiary                                 Maturity Date
------                     ------------------------     -----------                                 -------------
<S>                      <C>                          <C>                                         <C>
868684                   $    828,630                 RCPI Trust                                       6/1/01

868814                   $    500,000                 W12/14 Wall Acquisition Associates               6/4/01
                                                      L.L.C.

868611                   $    800,000                 405 Lexington, L.L.C.                           6/23/01

868619                   $  1,327,000                 Charleston Landings Associates L.P.              7/1/01

868877                   $    684,000                 Tst 300 Park, L.L.C.                             9/1/00

868897                   $    450,000                 Petula Associates, LTD                         10/21/00

868896                   $    635,850                 Praedium II Broadstone                         10/29/00

868931                   $  1,715,980                 Paramount Group, Inc.                          11/10/00

868934                   $    800,000                 Gainey Ranch Town Center                       12/23/00

868805                   $    526,837.50              233 Broadway Owners L.L.C.                     12/31/00

868806                   $    800,000                 425 Market Street                              12/31/00

868944                   $    600,000                 Commerce Plaza Partners                         1/24/01

868943                   $    450,000                 Cornerstone Two L.C.C.                          1/27/01

</TABLE>

TOTAL LETTERS OF CREDIT ISSUED TO JP MORGAN                       $10,118,297.50

<PAGE>   26

Schedule 5(c)
     (continued)

FIRST UNION LETTERS OF CREDIT

<TABLE>
<CAPTION>
      SUBSIDIARY         ISSUING BANK     LC#           STATED AMOUNT                BENEFICIARY                     EXPIRY DATE
      ----------         ------------     ---           -------------                -----------                     -----------
<S>                      <C>            <C>            <C>                      <C>                              <C>
OmniOffices, Inc.        First Union    S147299        $    37,192.04           Weeks Realty, L.P.                   May 31, 2000

OmniOffices, Inc         First Union    S139489        $   148,000.00           Connecticut General Life Ins.       April 30, 2000
                                                                                Co.

OmniOffices, Inc         First Union    S145655        $    46,000.00           Equitable Life Assurance          December 21, 1999
                                                                                Society of USA, Boston, MA

OmniOffices, Inc         First Union    S402898        $    50,000.00           Golub & Company                    August 31, 2000

HQ Business Centers of   First Union    S148598        $   600,000.00           Fairview Associates                August 31, 2000
North Carolina, Inc.

OmniOffices, Inc         First Union    S116794        $    24,221.33           American National Bank & Trust      June 30, 2000
                                                                                Co. of Chicago

OmniOffices, Inc         First Union    S108660        $   240,000.00           Trizechahn Office Holdings         August 31, 2000

OmniOffices, Inc         First Union    S402416        $    16,000.00           Talcott Realty I Ltd.               June 30, 2000

OmniOffices, Inc         First Union    SM408124C      $    31,751.76           EOP-Westchase Office Properties      May 30, 2000
                                                                                Trust

OmniOffices, Inc         First Union    S063275        $   140,000.00           Realty Bancorp                      March 15, 2000

OmniOffices, Inc         First Union    SM408488C      $    50,000.00           OTR                                January 31, 2000

Executive Office         First Union    S163998        $   775,000.00           Park Avenue Properties             October 15, 2000
Network, Ltd.

OmniOffices, Inc         First Union    S403D44        $   180,000.00           Carol Management Corp.               May 1, 2000

OmniOffices, Inc         First Union    S101387        $   750,000.00           Madison Avenue Associates          August 30, 2000

OmniOffices, Inc         First Union    S114735        $    33,124.05           Talcott Realty I Ltd.               April 30, 2000

OmniOffices, Inc         First Union    S104374        $   160,000.00           DRW Chesterbrook Associates        November 1, 2000

OmniOffices, Inc         First Union    S139498        $    40,000.00           Metro Corp Center, LLC             January 31, 2000

OmniOffices, Inc         First Union    SM408720C      $   250,000.00           Spieker Properties, LP             August 30, 2000

Kiowa, Inc.              First Union    S151696        $   800,000.00           Shorenstein Management, Inc.        April 15, 2000

OmniOffices, Inc         First Union    S111557        $   150,000.00           Acquiport Corp. Ridge, Inc.       February 20, 2000

                         First Union    S132017        $    70,000.00           Airlines Reporting Corp.          September 30, 2000
</TABLE>

TOTAL LETTER OF CREDIT FOR FIRST UNION                             $4,591,289.18<PAGE>   1

                                                                  EXHIBIT 10.11

                               PURCHASE AGREEMENT

         PURCHASE AGREEMENT, dated as of May 31, 2000, by and between FrontLine
Capital Group, a Delaware corporation ("FCG"), and Fortress HQ LLC, a Delaware
limited liability company (the "Investor").

         WHEREAS, HQ Global Workplaces Inc., a Delaware corporation ("Old HQ"),
and CarrAmerica Realty Corporation, a Maryland corporation ("CarrAmerica"), on
the one hand, and VANTAS Incorporated, a Nevada corporation ("VANTAS"), and FCG,
on the other hand, have entered into that certain Agreement and Plan of Merger,
dated as of January 20, 2000, as amended as of April 29, 2000 and as of May 30,
2000 (as amended, the "Merger Agreement").

         WHEREAS, pursuant to the Merger Agreement, VANTAS will merge with and
into Old HQ with Old HQ continuing as the surviving corporation with the name
"HQ Global Workplaces, Inc." (the "HQ Merger").

         WHEREAS, FCG and CarrAmerica have entered into that certain Stock
Purchase Agreement, dated as of January 20, 2000, as amended as of April 29,
2000 (as amended, the "Stock Purchase Agreement"), whereby FCG agreed to
purchase from CarrAmerica 4,130,530 shares of non-voting common stock, par value
$.01 per share (the "Old HQ Common Stock"), of Old HQ.

         WHEREAS, immediately following the consummation of the HQ Merger and
the transactions contemplated by the Stock Purchase Agreement and that certain
Stock Purchase Agreement, dated as of January 20, 2000, as amended as of April
29, 2000, among FCG, VANTAS, CarrAmerica, Omni Offices UK Limited and Omni
Offices (Lux) 1929 Holding Company S.A. (the "UK Stock Purchase Agreement"), Old
HQ, as the surviving corporation of the HQ Merger ("HQ Surviving Corporation"),
will merge (the "Second Step Merger") with and into newly formed HQ Merger
Subsidiary, Inc., a Delaware corporation ("M-Sub") that is a wholly owned
subsidiary of HQ Global Holdings, Inc., a Delaware corporation ("Holdco"), which
will theretofore be wholly owned by HQ Surviving Corporation, with M-Sub
continuing as the surviving corporation under the name "HQ Global Workplaces
Inc." pursuant to the Agreement and Plan of Merger related thereto (the "Second
Step Merger Agreement").

         WHEREAS, pursuant to the Exchange Agreement, dated as of May 31, 2000
(the "Exchange Agreement"), Holdco and FCG have agreed to exchange 4,130,530
shares of common stock of Holdco ("Common Shares") to be received by FCG in the
Second Step Merger in exchange for the Old HQ Common Stock to be purchased by
FCG from CarrAmerica and certain other persons pursuant to the Stock Purchase
Agreement for 3,704,933.820 newly issued shares of Series A Convertible
Cumulative Preferred Stock (the "Preferred Stock") of Holdco and warrants to
purchase up to 1,660,341.752 shares of voting common stock, par value $.01 per
share (the "Voting Common Stock"), of Holdco.

<PAGE>   2

         WHEREAS, upon consummation of the transactions contemplated in the
Exchange Agreement, FCG desires to sell to the Investor, and the Investor
desires to purchase from FCG, the certain securities on the terms and conditions
specified in this Agreement.

         WHEREAS, capitalized words and phrases used but not otherwise defined
herein shall have the meanings ascribed to them under the Merger Agreement.

         Accordingly, FCG and the Investor hereby agree as follows:

         1. Purchase and Sale of Securities. (a) On the terms and subject to the
conditions of this Agreement, (i) FCG agrees to sell to the Investor, and the
Investor agrees to purchase from FCG, for $45 million (the "Purchase Price") (A)
1,103,698.157 newly issued shares of Preferred Stock (the "Preferred Shares"),
the terms of which are contained in the certificate of designations to Holdco's
certificate of incorporation (the "Certificate of Designations") in the form
attached as Exhibit A hereto, having an initial liquidation preference equal to
$45 million and (B) warrants to purchase up to 494,615.077 shares of Voting
Common Stock (the "Warrants"), the terms of which are in the form attached as
Exhibit B hereto in respect of Warrants to purchase 333,546.462 shares of Common
Stock (the "Initial Warrants") and in Exhibit C hereto in respect of Warrants to
purchase 161,068.615 shares of Common Stock.

                  (b) The closing (the "Closing") of the purchase and sale of
the securities referred to in clause (a) above shall be held at the offices of
Brown & Wood LLP, One World Trade Center, New York, New York 10048, immediately
after, and on the same date as, the Closing under the Merger Agreement, subject
to the satisfaction or waiver of the conditions set forth in Section 5 hereof.
The date on which the Closing shall occur, which shall not extend beyond June 5,
2000, is hereinafter referred to as the "Closing Date," and, if the Closing Date
is not May 31, 2000, FCG shall notify the Investor prior to the close of the
business on the business day immediately preceding the Closing Date. On the
Closing Date, (i) FCG shall deliver certificates issued in the Investor's name
representing the Preferred Shares and the Warrants, and (ii) the Investor shall
deposit the Purchase Price in immediately available funds with Citibank, N.A.,
as escrow agent (the "Escrow Agent") under the Escrow Agreement, dated as of May
31, 2000 (the "Escrow Agreement"), for payment to FCG; it being understood that
the Closing shall occur, and the Preferred Shares, Warrants and Purchase Price
only released from escrow, in accordance with the terms and conditions set forth
in the Escrow Agreement.

         2. Representations and Warranties of FCG. FCG hereby represents and
warrants to the Investor as of the date hereof and as of the Closing Date as to
the following matters:

                  (a) Organization and Standing. FCG is a corporation duly
organized, validly existing and in good standing as a corporation under the laws
of the State of Delaware. FCG and its subsidiaries have all requisite corporate
power and authority necessary to carry on their respective businesses as
presently conducted and to enable them to own, lease or otherwise hold their
respective properties and assets. FCG and its subsidiaries are duly qualified to
do business and in good standing in each jurisdiction in which the conduct or
nature of their respective businesses or the ownership, leasing or holding of
their respective properties or assets makes

                                       2
<PAGE>   3

such qualification necessary, except any such jurisdiction where the failure to
be so qualified or in good standing, individually or in the aggregate, would not
have a material adverse effect on the business, financial condition or results
of operations of Holdco and its subsidiaries taken as a whole (an "FCG Material
Adverse Effect").

                  (b) Authority. FCG has all requisite corporate power and
authority to enter into this Agreement, to perform its obligations hereunder and
to consummate the transactions contemplated hereby. All corporate acts and other
proceedings required to be taken by FCG to authorize the execution, delivery and
performance of this Agreement and the consummation of the transactions
contemplated hereby have been duly and properly taken. This Agreement has been
duly executed and delivered by FCG and constitutes a legal, valid and binding
agreement of FCG, enforceable against FCG in accordance with its terms, except
insofar as enforcement thereof may be limited by bankruptcy, insolvency, or
other laws relating to or affecting enforcement of creditors' rights generally
or by general equitable principles.

                  (c) Preferred Shares and Warrants. (A) The Preferred Shares
have been duly authorized for issuance by Holdco pursuant to the terms of the
Exchange Agreement and, at Closing, (i) will be validly issued, fully paid and
nonassessable, (ii) will be free and clear of all Liens, other than transfer
restrictions relating to the federal securities laws, (iii) will not be issued
in violation of any preemptive or similar rights under any provisions of
applicable law, the certificate of incorporation or by-laws of Holdco or any
agreement, contract or instrument to which Holdco is a party or by which it or
any of its properties or assets is bound and (iv) assuming the accuracy of the
representations and warranties set forth in Section 3 of the Exchange Agreement
will be issued in compliance with the registration and qualification
requirements of all applicable federal securities laws as presently in effect.
The Warrants have been duly authorized for issuance by Holdco pursuant to the
terms of the Exchange Agreement and, at Closing, will be legal, valid and
binding obligations of Holdco, enforceable against Holdco in accordance with
their terms, except insofar as enforcement thereof may be limited by bankruptcy,
insolvency or other laws relating to or affecting enforcement of creditors'
rights generally or by general equity principles.

                  (B) On the Closing Date, FCG will be the sole record and
beneficial owner and holder of the Preferred Shares and the Warrants, free and
clear of all claims, conditional sale or other title retention agreements,
covenants, encumbrances, equitable interests, liens, options, pledges, rights
of first refusal, security interests, statutory liens or restrictions of any
kind, including any restrictions on voting, transfer, receipt of income, or
exercise of any other attribute of ownership ("Liens"). At the Closing, FCG
will transfer to the Investor good and marketable title to the Preferred Shares
and the Warrants, free and clear of all Liens. Except as contemplated in
Section 3(d), at the Closing, no legend or other reference to any purported
Lien will appear upon any certificate representing the Preferred Shares or the
Warrants. At the Closing, none of the Preferred Shares or the Warrants will be
transferred to FCG in violation of (i) the Securities Act of 1933, as amended
(the "Securities Act"), the securities laws of any state, or any other federal,
state, local, municipal, foreign, international, multinational, or other
constitution, law, rule, standard, requirement, administrative ruling, order,
ordinance, principle of

                                       3
<PAGE>   4

common law, legal doctrine, code, regulation, statute, treaty or process or (ii)
any award, decision, injunction, judgment, decree, settlement, order, process,
ruling, subpoena or verdict (whether temporary, preliminary or permanent)
entered, issued, made or rendered by any court, administrative agency,
arbitrator, Governmental Entity or other tribunal of competent jurisdiction.

                  (d) No Conflicts; Consents. The execution and delivery of this
Agreement by FCG does not, and the consummation of the transactions contemplated
hereby and compliance with the terms hereof will not conflict with, or result in
any violation of, or default (with or without notice or lapse of time, or both)
under, or give rise to a right of termination, cancellation or acceleration of
any obligation or to a material loss of a benefit under, or result in the
creation of any lien, charge or encumbrance of any kind upon any of the
properties or assets of FCG or its subsidiaries under, any provision of (i) the
certificate of incorporation or by-laws of FCG and its subsidiaries, (ii) any
note, bond, mortgage, indenture, deed of trust, license, lease, contract,
commitment, agreement or arrangement to which FCG or any of its subsidiaries is
a party or by which any of them or any of their respective properties or assets
is bound or (iii) subject to the governmental filings and other matters referred
to in the succeeding sentence, any judgment, order or decree, or statute, law,
ordinance, rule or regulation, applicable to FCG or any of its subsidiaries or
any of their respective properties or assets. Except for disclosure in any
reports required pursuant to the Securities Exchange Act of 1934, as amended
(the "Exchange Act"), no consent, approval, license, permit, order or
authorization of, or registration, declaration or filing with, any Governmental
Entity is required to be obtained or made by or with respect to FCG or any of
its subsidiaries in connection with the execution, delivery and performance by
Holdco of this Agreement or the consummation of the transactions contemplated
hereby.

         3. Representations and Warranties of the Investor. The Investor hereby
represents and warrants to FCG as follows:

                  (a) Organization and Standing. The Investor is a limited
liability company duly organized, validly existing and in good standing under
the laws of the State of Delaware. The Investor and its subsidiaries have all
requisite limited liability company or other power and authority necessary to
carry on their respective businesses as presently conducted and to enable them
to own, lease or otherwise hold their respective properties and assets. The
Investor and its subsidiaries are duly qualified to do business and are in good
standing in each jurisdiction in which the conduct or nature of their respective
businesses or the ownership, leasing or holding of their respective properties
or assets makes such qualification necessary, except any such jurisdiction where
the failure to be so qualified or in good standing, individually or in the
aggregate, would not have a material adverse effect on the business, financial
condition or results of operations of the Investor and its subsidiaries taken as
a whole (an "Investor Material Adverse Effect").

                  (b) Authority. The Investor has all requisite limited
liability company power and authority to enter into this Agreement, that certain
Registration Rights Agreement, in the form attached as Exhibit D hereto (the
"Registration Rights Agreement"), and that certain

                                       4
<PAGE>   5

Stockholders Agreement, in the form attached as Exhibit E hereto (the
"Stockholders Agreement"), to perform its obligations hereunder and thereunder
and to consummate the transactions contemplated hereby and thereby. All limited
liability company and other acts and other proceedings required to be taken by
the Investor to authorize the execution, delivery and performance of this
Agreement, the Registration Rights Agreement and the Stockholders Agreement and
the consummation of the transactions contemplated hereby and thereby have been
duly and properly taken. This Agreement has been, and, at the Closing, the
Registration Rights Agreement and the Stockholders Agreement will have each
been, duly executed and delivered by the Investor and each constitutes or will
constitute, as applicable, a legal, valid and binding obligation of the
Investor, enforceable against the Investor in accordance with its terms, except
insofar as enforcement thereof may be limited by bankruptcy, insolvency or other
laws relating to or affecting enforcement of creditors' rights generally or by
general equity principles.

                  (c) No Conflicts; Consents. The execution and delivery of this
Agreement, the Registration Rights Agreement and the Stockholders Agreement by
the Investor does not, and the consummation of the transactions contemplated
hereby and thereby and compliance by the Investor with the terms hereof and
thereof will not, conflict with, or result in any violation of or default (with
or without notice or lapse of time, or both) under, or give rise to a right of
termination, cancellation or acceleration of any obligation or to loss of a
material benefit under, or result in the creation of any lien, charge or
encumbrance of any kind upon any of the properties or assets of the Investor or
its subsidiaries under, any provision of (i) the declaration of trust,
partnership agreement, certificate of limited partnership, limited liability
company agreement, charter or by-laws of the Investor and its subsidiaries, (ii)
any note, bond, mortgage, indenture, deed of trust, loan document, license,
lease, contract, commitment, agreement or arrangement to which the Investor or
any of its subsidiaries is a party or by which any of them or any of their
respective properties or assets is bound or (iii) any judgment, order or decree,
or statute, law, ordinance, rule or regulation, applicable to the Investor or
any of its subsidiaries or any of their respective properties or assets. Except
for disclosure in any reports required pursuant to the Exchange Act, no consent,
approval, license, permit, order or authorization of, or registration,
declaration or filing with, any Governmental Entity is required to be obtained
or made by or with respect to the Investor in connection with the execution,
delivery and performance of this Agreement, the Registration Rights Agreement
and the Stockholders Agreement by the Investor or the consummation of the
transactions contemplated hereby and thereby.

                  (d) Investment Representation. The Investor is purchasing
Preferred Shares and Warrants pursuant to this Agreement for its own account for
investment only and not with a view towards their distribution or resale. The
Investor represents that it is an "accredited" investor within the meaning of
Rule 501 promulgated under the Securities Act of 1933, as amended (the
"Securities Act"), has such knowledge and experience in financial and business
matters that enable it to evaluate the merits and risks of investment in the
Preferred Shares and Warrants, is able to bear the economic risk of a loss of
its entire investment therein and is prepared to hold the Preferred Shares and
the Warrants for an indefinite period of time. The Investor has received the
opportunity to ask questions, and has obtained the related answers, regarding
the business,

                                       5
<PAGE>   6

financial condition and results of operations of Holdco, VANTAS and Old HQ and
the terms and conditions of the Preferred Shares and the Warrants. The Investor
has received all of the information regarding Holdco, VANTAS and Old HQ that it
has requested. FCG has informed the Investor that the Preferred Shares and the
Warrants have not been registered under the Securities Act and may not be sold,
transferred or otherwise assigned absent such registration or an exemption
therefrom. FCG has also informed the Investor that any routine sale of Preferred
Shares and Warrants made in reliance upon Rule 144 promulgated under the
Securities Act can be made only in accordance with the terms and conditions of
such Rule and, further, that in case such Rule is not applicable to any sale of
Preferred Shares and Warrants, as applicable, resale thereof may require
compliance with some other exemption under the Securities Act prior to resale.
FCG has informed the Investor that certificates representing the Preferred
Shares and Warrants issued pursuant to this Agreement bear the following legend:

         "THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
1933, AS AMENDED. SUCH SECURITIES MAY NOT BE SOLD OR OFFERED FOR SALE,
TRANSFERRED OR OTHERWISE ASSIGNED IN THE ABSENCE OF AN EFFECTIVE REGISTRATION
STATEMENT WITH RESPECT THERETO UNDER SUCH ACT OR AN EXEMPTION FROM REGISTRATION
FOR SUCH SALE, OFFER, TRANSFER OR OTHER ASSIGNMENT AS SUPPORTED BY SUCH
CERTIFICATIONS, OPINIONS AND OTHER DOCUMENTATION, IF ANY, AS ARE REASONABLY
REQUESTED AND ACCEPTABLE TO THE CORPORATION."

         4. Covenants.

                  (a) Transfer of Rights. At the Closing, FCG shall transfer,
assign and convey to the Investor any and all rights to which FCG is entitled
under the Exchange Agreement and in respect of the Preferred Shares and the
Warrants, all as set forth in the Assignment Agreement attached as Exhibit F
hereto.

                  (b) Consummation of the Transactions. Subject to the terms and
conditions of this Agreement, each party shall use its commercially reasonable
efforts to cause the Closing to occur upon the terms and conditions set forth
herein. FCG shall cooperate with the Investor, and the Investor shall cooperate
with FCG, in filing any necessary applications, reports or other documents with,
giving any notices to, and seeking any consents from, all Governmental Entities
and all third parties as may be required in connection with the consummation of
the transactions contemplated by this Agreement, and each party requesting such
cooperation shall reimburse the other party's reasonable out-of-pocket expenses
in providing such cooperation.

                  (c) Lock-Up. In connection with an initial public offering of
Holdco's securities, the Investor agrees, and the Investor shall secure the
agreement of any transferee therefrom, upon request of the lead underwriter, not
to sell or otherwise transfer or dispose of any Common Stock of Holdco (other
than to an affiliate of the Investor or another holder of Preferred Stock) for a
period following the effective date of a registration statement of Holdco filed
under the Securities Act with respect to such offering equal to the lesser of
(i) the lock-up period applicable to (a) FCG, (b) CarrAmerica (so long as it
owns in excess of 9% of the outstanding shares of

                                       6
<PAGE>   7

Common Stock), (c) holders of Preferred Stock, and (d) senior executive officers
of Holdco and (ii) six (6) months.

         5. Conditions to Closing.

                  (a) Each Party's Obligation. The respective obligations of
each party hereto to effect the transactions contemplated by this Agreement are
subject to the satisfaction (or waiver) as of the Closing of the following
conditions: (i) the HQ Merger and the Second Step Merger shall have been
consummated; (ii) no statute, rule, regulation, executive order, decree,
temporary restraining order, preliminary or permanent injunction or other order
shall have been enacted, entered, promulgated, enforced or issued by any
Governmental Entity that prohibits the performance of this Agreement or the
consummation of the transactions contemplated by this Agreement; and (iii) no
action, claim, proceeding or investigation shall be pending or threatened by any
Governmental Entity (other than a court acting in response to an action, claim
or proceeding brought by a non-Governmental Entity) that, if successful, would
prohibit the performance of this Agreement or the consummation of the
transactions contemplated by this Agreement.

                  (b) FCG's Obligation. The obligations of FCG hereunder are
subject to the satisfaction (or waiver by FCG) as of the Closing of the
following conditions:

                  (i) The representations and warranties of the Investor made in
this Agreement shall be true and correct as of the date hereof and as of the
time of the Closing as though made as of such time, except (1) to the extent
such representations and warranties expressly relate to an earlier date (in
which case such representations and warranties shall be true and correct on and
as of such earlier date) or (2) where the failure of any representations and
warranties other than the representations and warranties set forth in Sections
3(b) and 3(d) to be true and correct would not have an Investor Material Adverse
Effect, and the Investor shall have duly performed, complied with and satisfied
in all material respects all covenants, agreements and conditions required by
this Agreement to be performed, complied with or satisfied by the Investor by
the time of Closing. At the Closing, the Investor shall have delivered to FCG a
certificate, dated the Closing Date and signed by a representative of the
Investor, confirming the foregoing.

                  (ii) At the Closing, the Investor shall have delivered to
Holdco a certificate, dated the Closing Date, attesting to the authorization of
the Investor to consummate the transactions contemplated by this Agreement.

                  (iii) All filings, registrations, authorizations, permits,
consents and approvals required for the Investor's consummation of the
transactions contemplated by this Agreement shall have been made or obtained, as
applicable.

                  (iv) At the Closing, the Investor shall have executed and
delivered to Holdco the Stockholders Agreement and the Registration Rights
Agreement and (assuming due execution and delivery by the other parties thereto)
the same shall be in full force and effect.

                                       7
<PAGE>   8

                  (v) At the Closing, the Investor shall have deposited the
Purchase Price in immediately available funds with the Escrow Agent.

         (c) The Investor's Obligation. The obligations of the Investor
hereunder are subject to the satisfaction (or waiver by the Investor) as of the
Closing of the following conditions:

                  (i) The representations and warranties of FCG made in this
Agreement shall be true and correct as of the date hereof and as of the time of
the Closing as though made as of such time, except (1) to the extent such
representations and warranties expressly relate to an earlier date (in which
case such representations and warranties shall be true and correct on and as of
such earlier date) or (2) where the failure of any representations and
warranties other than the representations and warranties set forth in Section
2(c) to be true and correct would not have an FCG Material Adverse Effect, and
FCG shall have duly performed, complied with and satisfied in all material
respects all covenants, agreements and conditions required by this Agreement to
be performed, complied with or satisfied by FCG by the time of Closing. At the
Closing, FCG shall have delivered to the Investor a certificate, dated the
Closing Date and signed by an officer of FCG, confirming the foregoing.

                  (ii) The representations and warranties of Holdco made in the
Exchange Agreement shall be true and correct as of the date of the Exchange
Agreement and as of the time of the Closing as though made as of such time,
except (1) to the extent such representations and warranties expressly relate to
an earlier date (in which case such representations and warranties shall be true
and correct on and as of such earlier date), (2) where the failure of any
representations and warranties other than the representations and warranties set
forth in Sections 2(d), (e), (f) or (g) of the Exchange Agreement to be true and
correct would not have a Holdco Material Adverse Effect (as defined in the
Exchange Agreement) or (3) that the representation and warranty set forth in
Section 2(d) of the Exchange Agreement shall be true and correct other than in
any de minimis respect, the acquisition by FCG of the Preferred Shares and
Warrants pursuant to the Exchange Agreement shall have been consummated, and all
conditions specified in the Exchange Agreement shall have been satisfied, and
there shall have been no waivers to such conditions.

                  (iii) At the Closing, FCG shall have delivered to the Investor
a secretary's certificate, dated the Closing Date, attesting to the
authorization of FCG to consummate the transactions contemplated by this
Agreement.

                  (iv) Since the date of this Agreement, Holdco and its
subsidiaries taken as a whole shall not have suffered a Holdco Material Adverse
Effect.

                  (v) All filings, registrations, authorizations, permits,
consents and approvals required for FCG's consummation of the transactions
contemplated by this Agreement shall have been made or obtained, as applicable.

                                       8
<PAGE>   9

                  (vi) At the Closing, Holdco shall have executed and delivered
to the Investor the Stockholders Agreement and the Registration Rights Agreement
and (assuming due execution and delivery by the other parties thereto) the same
shall be in full force and effect.

                  (vii) At the Closing, FCG shall have executed and delivered to
the Investor the Assignment Agreement in the form of Exhibit F hereto and
(assuming due execution and delivery by the Investor) the same shall be in full
force and effect.

                  (viii) At or prior to the Closing, Holdco or Old HQ shall have
received debt financing the terms of which are substantially to the effect set
forth in the commitment letter of Paribas attached as Exhibit G hereto in
respect of the bank term debt and either the commitment letter of Blackstone
attached as Exhibit H hereto in respect of the high yield or mezzanine debt or
the commitment letter of Warburg Dillon Read LLC attached as Exhibit I hereto in
respect of bridge financing, whether such financing is obtained from such
parties or any other party, and, at the Closing, except as disclosed in Schedule
5(c), no other indebtedness of Holdco for borrowed money shall be outstanding.

                  (ix) At or prior to Closing, the Certificate of Designations
in the form of Exhibit K hereto shall have been accepted for filing by, and duly
filed with, the Secretary of State of the State of Delaware.

                  (x) At the Closing, the Investor shall have received the
favorable opinion, dated the Closing Date, of Brown & Wood LLP, counsel to
Holdco and FCG, substantially in the form attached as Exhibit J hereto.

                  (xi) At the Closing, the Investor shall have received an
agreed upon procedures letter, dated the Closing Date, from Ernst & Young LLP,
substantially in the form attached as Exhibit K hereto.

                  (xii) At the Closing, none of the Merger Agreement, the Second
Step Merger Agreement and the UK Stock Purchase Agreement shall have been
amended in any material respect other than an extension of the Closing of the
transactions contemplated thereunder until June 5, 2000, and the conditions
specified in the Merger Agreement, the Second Step Merger Agreement and the UK
Stock Purchase Agreement shall have been satisfied in all material respects, and
there shall have been no waivers to such conditions in any material respect.

                  (xiii) At the Closing, EOP Operating Limited Partnership or an
affiliate thereof shall purchase Preferred Stock and Warrants from Holdco and
FCG for an aggregate amount of $75 million.

                  (xiv) At the Closing, the Investor shall have received an
executed Management Rights Letter substantially in the form attached as Exhibit
L hereto and an opinion of counsel from Holdco stating that Holdco is an
operating company within the meaning of the Plan Asset Regulations.

                                       9
<PAGE>   10

                  (xv) At the Closing, FCG shall have delivered the Preferred
Shares and the Warrants to the Investor.

               (d) Frustration of Closing Conditions. Neither FCG nor the
Investor may rely on the failure of any condition set forth in Section 5(a),
Section 5(b) or Section 5(c), respectively, to be satisfied if such failure was
caused by such party's failure to perform its obligations hereunder or to use
its commercially reasonable efforts to cause the Closing to occur as required by
Section 5.

         6. Further Assurances. From time to time, as and when requested by
another party hereto, a party hereto shall execute and deliver, or cause to be
executed and delivered, all such documents and instruments and shall take, or
cause to be taken, all such further or other actions as such other party may
reasonably deem necessary or desirable to consummate the transactions
contemplated by this Agreement.

         7. Assignment. This Agreement and the rights and obligations hereunder
shall not be assignable or transferable by (i) FCG without the prior written
consent of the Investor or (ii) by the Investor without the prior written
consent of Holdco and FCG. Any attempted assignment in violation of this Section
7 shall be void ab initio and of no further force and effect.

         8. No Third-Party Beneficiaries. This Agreement is for the sole benefit
of the parties hereto and their successors and permitted assigns, and nothing
herein expressed or implied shall give or be construed to give to any person,
other than the parties hereto and such permitted successors and assigns, any
legal or equitable rights hereunder.

         9. Amendments. No amendment, modification or waiver in respect of this
Agreement shall be effective unless it shall be in writing and signed by the
party against whom such amendment, modification or waiver is asserted.

         10. Representations, Warranties and Agreements to Survive Delivery. All
representations, warranties and agreements contained in this Agreement or in
certificates of officers of FCG or the Investor submitted pursuant hereto shall
remain operative and in full force and effect for a period of one year (or, in
the case of the representation and warranty specified in Section 5(A)(b) of the
Merger Agreement, for the period of any applicable statute of limitations)
following the Closing. Notwithstanding anything to the contrary contained in the
foregoing, nothing in this Section 10 is intended to indicate that any
representation or warranty will be true at any time other than at the time of
execution of this Agreement and at the Closing.

                                       10
<PAGE>   11

         11. Indemnification.

                  (a) Indemnity by FCG and Holdco. FCG and Holdco, jointly and
severally, shall indemnify the Investor and its affiliates, controlling persons,
constituent partners and subsidiaries and their directors, officers, members,
employees, attorneys and representatives against all expenses, costs, losses,
claims, damages, liabilities and judgments (including, without limitation,
reasonable attorney's fees and expenses) incurred or sustained by any such party
resulting from (i) any breach of the representations and warranties of FCG set
forth in Section 2 or of Holdco in Section 2 of the Exchange Agreement, (ii)
FCG's, Holdco's or VANTAS' acts or failure to act, (iii) any misstatements or
omissions made in any disclosure or other information or materials delivered or
made available to the Investor in connection with the investment contemplated
under this Agreement, (iv) the action or failure to act by an indemnified party
with FCG's, Holdco's or VANTAS' consent or in reliance on FCG's, Holdco's or
VANTAS' action or failure to act or (v) any and all environmental liabilities
costs and expenses arising out of or incurred in connection with the
consummation of the Merger, the Second Step Merger or the investment
contemplated in this Agreement; provided, however, that such indemnity shall not
extend to any expenses, costs, losses, claims, damages, liabilities or judgments
to the extent arising out of (A) the gross negligence or willful misconduct of
any person indemnified under this Section 11(a) as determined by a court of
competent jurisdiction in a final, non-appealable judgment or (B) a breach by
the Investor of its representations and warranties contained herein.

         FCG agrees to indemnify the Investor against any Company Level Loss or
Direct Loss (each as defined below) arising out of (i) Rule 10b-5 under the
Exchange Act with respect to VANTAS' failure to file reports with the Securities
and Exchange Commission as required under the Exchange Act prior to the date
hereof or (ii) the Shareholder Litigation (as defined in the Form of
Indemnification and Escrow Agreement attached as Exhibit E to the Merger
Agreement (the "Indemnification Agreement"). FCG shall pay the Investor, in full
and complete satisfaction of FCG's obligation under clause (ii) of this
paragraph, an amount (which, in the case of a Direct Loss, shall not exceed such
Direct Loss) equal to the product of (A) a fraction, the numerator of which
equals the sum of the number of shares of Preferred Stock (determined on an
As-Converted Basis) and the number of shares of Common Stock purchasable upon
exercise of the Initial Warrants, in each case owned by the Investor at the
Closing, and the denominator of which equals the sum of the number of shares of
Preferred Stock (determined on an As-Converted Basis) and the number of shares
of Common Stock purchasable upon exercise of the Initial Warrants, in each case
owned by the Investor at the Closing, and the number of shares of Common Stock
owned by FCG at the Closing, multiplied by (B) the dollar value of any recovery
obtained by FCG from CarrAmerica under the Indemnification Agreement. A "Company
Level Loss" shall mean any loss, liability, claim, damage or expense (including,
without limitation, reasonable attorney's fees and expenses) incurred by Holdco
or Old HQ or its successor; it being understood that a Company Level Loss shall
not include (i) any consequential, incidental or punitive damages or (ii) any
Direct Loss; it being understood that a Company Level Loss shall include any
loss or damage suffered by the Investor as a result of a diminution in value
(either directly or indirectly) of the interest held by the Investor in Holdco.
A "Direct Loss" shall mean any loss, liability, claim, damage or expense
(including reasonable attorney's fees and expenses)

                                       11
<PAGE>   12

incurred by the Investor; it being understood that a Direct Loss shall not
include (i) any consequential, incidental or punitive damages, (ii) any Company
Level Loss or (iii) any loss or damage suffered by the Investor as a result of a
diminution in value (either directly or indirectly) of the interest held by the
Investor in Holdco.

         (b) Indemnity by the Investor. The Investor shall indemnify FCG, Holdco
and their respective directors, officers and employees against all expenses,
costs, losses, claims, damages, liabilities and judgments (including, without
limitation, reasonable attorney's fees and expenses) incurred or sustained by
any such party resulting from any breach of the representations and warranties
of the Investor set forth in Section 3; provided, however, that such indemnity
shall not extend to any expenses, costs, losses, claims, damages, liabilities
and judgments to the extent arising out of (A) the gross negligence or willful
misconduct of any person indemnified under this Section 11(b) as determined by a
court of competent jurisdiction in a final, non-appealable judgment or (B) a
breach by FCG or Holdco, as the case may be, of the representations and
warranties set forth in Section 2 of this Agreement or Section 2 of the Exchange
Agreement, respectively. Under no circumstances shall the Investor be liable to
FCG, Holdco or any other indemnified party under this Section 11(b) for any
punitive, exemplary, consequential or indirect damages arising therefrom.

         (c) Notice of Actions or Proceedings. In case any action or proceeding
shall be commenced involving any party in respect of which indemnity may be
sought pursuant to Sections 11(a) or 11(b) (the "indemnified party"), the
indemnified party shall promptly notify the party against whom such indemnity
may be sought (the "indemnifying party") in writing of such action or
proceeding; provided, however, that failure of an indemnified party to provide
such notice shall not relieve the indemnifying party of its obligations under
this Section 11 if such failure does not materially and adversely affect the
rights of the indemnifying party.

         (d) Defense of Actions and Proceedings. The indemnifying party may
assume the defense of such action or proceeding provided that the expenses of
the indemnified party are reimbursed as they are incurred (including, without
limitation, the payment of all reasonable and documented fees and expenses of
counsel to the indemnified party) and the indemnifying party has not failed to
comply with any such reimbursement request. Any indemnified party shall have the
right to employ separate counsel in any such action or proceeding and
participate in the defense thereof, but the reasonable fees and expenses of such
counsel shall be at the expense of the indemnified party, unless (i) the
employment of such counsel shall have been specifically authorized in writing by
the indemnifying party, (ii) the indemnifying party shall have failed to assume
the defense of such action or proceeding or (iii) the named parties to any such
action (including any impleaded parties) include both the indemnified party and
the indemnifying party, and the indemnified party shall have been reasonably
advised by such counsel that the representation of the indemnifying party and
the indemnified party by the same counsel would be inappropriate due to actual
or potential differing interests between the indemnifying party and the
indemnified party or there are defenses that are available to the indemnified
party that may be in conflict with or contradict those available to the
indemnifying party (in which case the indemnifying party shall not have the
right to assume the defense of such action on behalf of the

                                       12
<PAGE>   13

indemnified party). In any such case, the indemnifying party shall not, in
connection with any one action or separate but substantially similar or related
actions or proceedings in the same jurisdiction arising out of the same general
allegations or circumstances, be liable for the reasonable fees and expenses of
more than one separate firm of attorneys for all indemnified parties and all
such reasonable fees and expenses shall be reimbursed as they are incurred. The
indemnifying party shall indemnify and hold harmless the indemnified party from
and against any and all expenses, costs, losses, claims, damages, liabilities
and judgments by reason of any settlement made by the indemnified party of any
action effected with the indemnifying party's written consent. The indemnifying
party shall not, without the prior written consent of the indemnified party,
effect any settlement or compromise of, or consent to the entry of judgment with
respect to, any pending or threatened action or proceeding in respect of which
the indemnified party is or could have been a party and indemnity may be or
could have been sought hereunder by the indemnified party, unless (i) such
settlement, compromise or judgment includes an unconditional release of the
indemnified party from all liability on claims that are the subject matter of
such action or proceeding and does not include a statement as to or an admission
of fault or culpability by or on behalf of the indemnified party and (ii)
reasonable prior written notice of settlement, compromise or judgment is given
to the indemnified party.

         12. Notices. All notices or other communications required or permitted
to be given hereunder shall be in writing and shall be delivered by hand or sent
by prepaid telex, cable or telecopy or sent, postage prepaid, by registered,
certified or express mail or reputable overnight courier service and shall be
deemed given when so delivered by hand, telexed, cabled or telecopied, or if
mailed, three days after mailing (one business day in the case of express mail
or overnight courier service), as follows:

                  (i)      if to FCG,

                           FrontLine Capital Group
                           1350 Avenue of the Americas
                           New York, New York.  10019
                           Attention: Jason M. Barnett, Esq.
                                        General Counsel
                           Tel: (212) 931-8000
                           Fax: (212) 931-8001

                           with copies to:

                           Edward F. Petrosky, Jr., Esq.
                           J. Gerard Cummins, Esq.
                           Brown & Wood LLP
                           One World Trade Center
                           New York, New York  10048
                           Tel: (212) 839-5300
                           Fax: (212) 839-5599

                                       13

<PAGE>   14

                  (ii)     if to the Investor,

                           Fortress Investment Group LLC
                           1301 Avenue of the Americas
                           42nd Floor
                           New York, New York 10019
                           Tel: (212) 798-6100
                           Fax: (212) 798-6060
                           Attn: Chief Financial Officer

                           with copies to:

                           Sullivan & Cromwell
                           125 Broad Street
                           New York, New York 10004
                           Tel: (212) 558-4000
                           Fax: (212) 558-3588
                           Attn: Gary Israel
                                 Gerald D. Shepherd

or such other address as any party may from time to time specify by written
notice to the other parties hereto.

         13. Interpretation; Exhibits and Schedules. The headings contained in
this Agreement and in any Exhibit to this Agreement are for reference purposes
only and shall not affect in any way the meaning or interpretation of this
Agreement. All Exhibits annexed hereto or referred to herein are hereby
incorporated in and made a part of this Agreement as if set forth in full
herein. Any capitalized term used in any Exhibit but not otherwise defined
therein shall have the meaning ascribed to it in this Agreement. This Agreement
is gender neutral. Any word in this Agreement that refers to a particular gender
shall also refer to all other genders, including masculine, feminine and neuter.

         14. Counterparts. This Agreement may be executed in one or more
counterparts, all of which shall be considered one and the same agreement, and
shall become effective when one or more such counterparts have been signed by
each of the parties and delivered to the other party.

         15. Entire Agreement. This Agreement contains the entire agreement and
understanding between the parties hereto with respect to the subject matter
hereof and supersedes all prior agreements and understandings relating to such
subject matter. The parties hereto shall not be liable or bound to any other
party in any manner by any representations, warranties or covenants relating to
such subject matter except as specifically set forth herein.

         16. Brokers. Each party hereto hereby represents and warrants that no
brokers or finders have acted for such party in connection with this Agreement.

                                       14
<PAGE>   15

         17. Severability. If any provision of this Agreement (or any portion
thereof) or the application of any such provision (or any portion thereof) to
any person or circumstance shall be held invalid, illegal or unenforceable in
any respect by a court of competent jurisdiction, such invalidity, illegality or
unenforceability shall not affect any other provision hereof (or the remaining
portion thereof) or the application of such provision to any other persons or
circumstances.

         18. Consent to Jurisdiction. The Investor and FCG agree to commence any
action, suit or proceeding arising out of this Agreement or transactions
contemplated hereby against the other party either in a federal court located in
the State of New York or if such suit, action or other proceeding may not be
brought in such court for jurisdictional reasons, in a New York state court.
Each party to this Agreement submits and consents to personal jurisdiction in
any such litigation. The Investor and FCG further agree that service of any
process, summons, notice or document delivered by U.S. registered mail to such
party's respective address set forth above shall be effective service of process
for any action, suit or proceeding in New York with respect to any matters to
which it has submitted to jurisdiction in this Section 18. The Investor and FCG
irrevocably and unconditionally waive any objection to the laying of venue of
any action, suit or proceeding arising out of this Agreement or the transactions
contemplated hereby in (i) any New York state court or (ii) any federal court
located in the State of New York, and hereby further irrevocably and
unconditionally waives and agrees not to plead or claim in any such court that
any such action, suit or proceeding brought in any such court has been brought
in an inconvenient forum. EACH OF THE PARTIES HERETO IRREVOCABLY WAIVES TRIAL BY
JURY IN ANY ACTION OR PROCEEDING WITH RESPECT TO THIS AGREEMENT.

         19. Governing Law. This Agreement shall be governed by and construed in
accordance with the internal laws of the State of New York applicable to
agreements made and to be performed entirely within such State, without regard
to the conflicts of law principles of such State.

                                       15
<PAGE>   16

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed as of the date first written above.

                                    FRONTLINE CAPITAL GROUP

                                    By:
                                       ---------------------------------
                                       Name:
                                       Title:

                                    HQ GLOBAL HOLDINGS, INC.,
                                       solely as to its express obligations
                                       under Section 11

                                    By:
                                       ---------------------------------
                                       Name:
                                       Title:

                                    FORTRESS HQ LLC

                                    By:
                                       ---------------------------------
                                       Name:
                                       Title:

                                       16
<PAGE>   17

                                  SCHEDULE 2(C)

                                     Nothing

<PAGE>   18

                                  SCHEDULE 2(d)

                          CAPITAL STOCK OF THE COMPANY

1.       Section 5 of the Stockholders Agreement, dated as of the date hereof
         (the "CarrAmerica Stockholders Agreement"), by and among FrontLine
         Capital Group, HQ Global Holdings, Inc. and CarrAmerica Realty
         Corporation contains Participation Rights granting CarrAmerica the
         right to purchase its "pro rata share" of any issuance by the Company
         of equity securities (subject to certain qualifications).

2.       Section 5 of the Stockholders Agreement, dated the date hereof, by and
         among FrontLine Capital Group, HQ Global Holdings, Inc. and certain
         holders of Series A Preferred Stock contains Participation Rights
         granting holders of Series A Preferred Stock the right to purchase
         their "pro rata share" of any issuance by the Company of equity
         securities (subject to certain qualifications).

3.       Warrants to purchase 2,143,332 shares of Common Stock (subject to
         antidilution rights), dated the date hereof, issued to holders of
         Series A Preferred Stock.

4.       Warrants to purchase 1,498,538 shares of Common Stock (subject to
         antidilution rights), dated the date hereof, issued to UBS AG Stamford
         Branch.

5.       Warrant Agreement dated as of March 4, 1998 by and between OmniOffices,
         Inc. and Robert A. Arcoro for the purchase of 100,000 shares at $20.00
         per share. Mr. Arcoro has exercised his warrant for 99,000 shares. Only
         1,000 shares remain subject to this agreement.

6.       Warrant Agreement dated as of March 4, 1998 by and between OmniOffices,
         Inc. and Joseph Kaidanow for the purchase of 85,000 shares at $20.00
         per share. Mr. Kaidanow has exercised his warrant for 50,000 shares.
         Only 35,000 shares remain subject to this agreement.

7.       Warrant Agreement dated as of March 4, 1998 by and between OmniOffices,
         Inc. and Kimberly L. Arcoro for the purchase of 32,500 shares at $20.00
         per share.

8.       Warrant Agreement dated as of March 4, 1998 by and between OmniOffices,
         Inc. and Robert A. Arcoro, Jr. for the purchase of 32,500 shares at
         $20.00 per share.

         o        The Company is obligated to have authorized and in reserve the
                  shares of common stock receivable upon exercise of each of the
                  warrants under the Warrant Agreements.

         o        In the event the Company issues non-voting common stock of the
                  Company that is less than fair market value (other than stock
                  options or restricted stock

<PAGE>   19

                  pursuant to stock options plans) the warrantholders are
                  entitled to an adjustment of the warrant shares purchasable
                  under the Warrant.

         o        The Warrant Agreements contain antidilution provisions that
                  are triggered by distributions to holders of equity capital
                  stock (dividends) and the repurchase of common stock by the
                  Company of common stock at a price that is greater than the
                  fair market value of common stock on the date of the
                  repurchase.

9.       Purchase Right Agreement, dated as of March 4, 1998, by and among
         OmniOffices, Inc., Robert A. Arcoro and Joseph Kaidanow pursuant to
         which if immediately prior the first date on which 20% or more of the
         outstanding shares of common stock of the Company have been publicly
         distributed or registered and such shares are publicly traded on a
         national exchange or over-the-counter market, the debt ratio is less
         than 55.0% (the Company is obligated to offer the warrantholders the
         right to purchase up to an aggregate of 6,818 shares of common stock of
         the Company per percentage point below the 55.0% (subject to the
         adjustments set forth in Section 5(a) of the Warrant Agreement). This
         Purchase Right is subject to antidilution protection for the benefit of
         the Company pursuant to Section 10 of the CarrAmerica Stockholders
         Agreement.

10.      [Gary Kusin holds rights to receive 120,000 shares of Class B
         Non-Voting Stock and 300,000 options to acquire Non-Voting Common Stock
         pursuant to his employment contract. These rights accelerate in vesting
         upon a change in control.]

11.      Pursuant to the Merger Agreement, at the effective time of the Merger,
         each outstanding option to purchase shares of VANTAS Common Stock
         granted under the VANTAS 1996 Stock Option Plan (the "VANTAS 1996 Stock
         Options"), is automatically amended to constitute an option to acquire
         the number of shares of Voting Common Stock of the Company as the
         holder of such VANTAS 1996 Stock Option would have been entitled to
         receive as Merger Consideration in the Merger had such holder exercised
         such VANTAS 1996 Stock Option (free of and without regard to any
         limitation on the vesting of the right to exercise such VANTAS 1996
         Stock Option) immediately prior to the effective time of the Merger at
         an exercise price equal to the quotient of (a) the applicable exercise
         price for each such VANTAS 1996 Stock Option immediately prior to the
         effective time of the Merger divided by (b) the Conversion Ratio.

         The following is a list of options granted under the VANTAS 1996 Stock
         Option Plan that are subject to the foregoing:

         o        36,750 Options at an exercise price of $2.00

         o        250 Options at an exercise price of $4.75

         o        40,458 Options at an exercise price of $4.00

                                        2
<PAGE>   20

12.      As soon as practicable following the effective time of the Merger, Mr.
         Gary Kusin and Mr. David Rupert will receive options to purchase common
         stock of the Company with a value equal to 6X and 4X, respectively, of
         their respective Base Compensation, or $3,600,000 or $1,600,000,
         respectively, which will become exercisable over a four-year period
         (37.5% after 18 months, then 12.5% every 6 months up to 100% in total,
         provided in each case that the executive is still employed by the
         Company on the applicable vesting date). The exercise price per share
         will equal the per share valuation used for purposes of the Merger.

13.      As soon as practicable following the effective time of the Merger, Mr.
         Kusin and Mr. Rupert will receive a grant of restricted common stock in
         the Company with a value equal to 2.5X and 1.5X, respectively, of their
         respective Base Compensation, or $1,500,000 or $600,000, respectively,
         which will become vested over a four-year period (37.5% after 18
         months, then 12.5% every 6 months up to 100% in total, provided in each
         case that the executive is still employed by the Company on the
         applicable vesting date).

14.      It is anticipated that options and restricted stock with respect to 3%
         and 1%, respectively, of the outstanding common and preferred stock of
         the Company will be issued in connection with employee incentive
         compensation.

                                       3

<PAGE>   21

                                  SCHEDULE 5(c)

                HQ Global Holdings, Inc: Outstanding Indebtedness
                           Existing Letters of Credit

JP MORGAN LETTERS OF CREDIT

<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------
LC#                      Letter of Credits Issued     Beneficiary                                 Maturity Date
----------------------------------------------------------------------------------------------------------------------
<S>                      <C>                          <C>                                         <C>
868684                   $    828,630                 RCPI Trust                                      6/1/01
----------------------------------------------------------------------------------------------------------------------
868814                   $    500,000                 W12/14 Wall Acquisition Associates              6/4/01
                                                      L.L.C.
----------------------------------------------------------------------------------------------------------------------
868611                   $    800,000                 405 Lexington, L.L.C.                          6/23/01
----------------------------------------------------------------------------------------------------------------------
868619                   $  1,327,000                 Charleston Landings Associates L.P.             7/1/01
----------------------------------------------------------------------------------------------------------------------
868877                   $    684,000                 Tst 300 Park, L.L.C.                            9/1/00
----------------------------------------------------------------------------------------------------------------------
868897                   $    450,000                 Petula Associates, LTD                         10/21/00
----------------------------------------------------------------------------------------------------------------------
868896                   $    635,850                 Praedium II Broadstone                         10/29/00
----------------------------------------------------------------------------------------------------------------------
868931                   $  1,715,980                 Paramount Group, Inc.                          11/10/00
----------------------------------------------------------------------------------------------------------------------
868934                   $    800,000                 Gainey Ranch Town Center                       12/23/00
----------------------------------------------------------------------------------------------------------------------
868805                   $ 526,837.50                 233 Broadway Owners L.L.C.                     12/31/00
----------------------------------------------------------------------------------------------------------------------
868806                   $    800,000                 425 Market Street                              12/31/00
----------------------------------------------------------------------------------------------------------------------
868944                   $    600,000                 Commerce Plaza Partners                        1/24/01
----------------------------------------------------------------------------------------------------------------------
868943                   $    450,000                 Cornerstone Two L.C.C.                         1/27/01
----------------------------------------------------------------------------------------------------------------------
</TABLE>

TOTAL LETTERS OF CREDIT ISSUED TO JP MORGAN                      $10,118,297.50

<PAGE>   22

Schedule 5(c)
     (continued)

FIRST UNION LETTERS OF CREDIT

<TABLE>
<CAPTION>
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      SUBSIDIARY         ISSUING BANK     LC#           STATED AMOUNT                BENEFICIARY                     EXPIRY DATE
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<S>                      <C>            <C>            <C>                      <C>                              <C>
OmniOffices, Inc.        First Union    S147299        $    37,192.04           Weeks Realty, L.P.                   May 31, 2000
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OmniOffices, Inc         First Union    S139489        $   148,000.00           Connecticut General Life Ins.       April 30, 2000
                                                                                Co.
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OmniOffices, Inc         First Union    S145655        $    46,000.00           Equitable Life Assurance          December 21, 1999
                                                                                Society of USA, Boston, MA
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OmniOffices, Inc         First Union    S402898        $    50,000.00           Golub & Company                    August 31, 2000
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HQ Business Centers of   First Union    S148598        $   600,000.00           Fairview Associates                August 31, 2000
North Carolina, Inc.
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OmniOffices, Inc         First Union    S116794        $    24,221.33           American National Bank & Trust      June 30, 2000
                                                                                Co. of Chicago
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OmniOffices, Inc         First Union    S108660        $   240,000.00           Trizechahn Office Holdings         August 31, 2000
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OmniOffices, Inc         First Union    S402416        $    16,000.00           Talcott Realty I Ltd.               June 30, 2000
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OmniOffices, Inc         First Union    SM408124C      $    31,751.76           EOP-Westchase Office Properties      May 30, 2000
                                                                                Trust
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OmniOffices, Inc         First Union    S063275        $   140,000.00           Realty Bancorp                      March 15, 2000
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OmniOffices, Inc         First Union    SM408488C      $    50,000.00           OTR                                January 31, 2000
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Executive Office         First Union    S163998        $   775,000.00           Park Avenue Properties             October 15, 2000
Network, Ltd.
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OmniOffices, Inc         First Union    S403D44        $   180,000.00           Carol Management Corp.               May 1, 2000
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OmniOffices, Inc         First Union    S101387        $   750,000.00           Madison Avenue Associates          August 30, 2000
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OmniOffices, Inc         First Union    S114735        $    33,124.05           Talcott Realty I Ltd.               April 30, 2000
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OmniOffices, Inc         First Union    S104374        $   160,000.00           DRW Chesterbrook Associates        November 1, 2000
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OmniOffices, Inc         First Union    S139498        $    40,000.00           Metro Corp Center, LLC             January 31, 2000
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OmniOffices, Inc         First Union    SM408720C      $   250,000.00           Spieker Properties, LP             August 30, 2000
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Kiowa, Inc.              First Union    S151696        $   800,000.00           Shorenstein Management, Inc.        April 15, 2000
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OmniOffices, Inc         First Union    S111557        $   150,000.00           Acquiport Corp. Ridge, Inc.       February 20, 2000
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                         First Union    S132017        $    70,000.00           Airlines Reporting Corp.          September 30, 2000
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</TABLE>

TOTAL LETTER OF CREDIT FOR FIRST UNION                             $4,591,289.18

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00013-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00013-of-00352.parquet"}]]