Document:

Exhibit 10.5

 

PRIVATE PLACEMENT UNIT SUBSCRIPTION AGREEMENT

 

This PRIVATE PLACEMENT UNIT
SUBSCRIPTION AGREEMENT (this “Agreement”) is made as of the _____ day of ______, 2021, by and between Mount
Rainier Acquisition Corp., a Delaware corporation (the “Company”), DC RAINIER SPV LLC, a Delaware limited liability
company, and the undersigned parties listed under “Subscriber” on the signature page hereto (each a “Subscriber”
and collectively, the “Subscriber”).

 

WHEREAS, the Company desires
to sell and each of the Subscribers severally agrees to purchase, the number of private placement units set forth opposite the respective
Subscriber’s name on Schedule I hereof on a private placement basis (the “Sale”) for an aggregate of 551,200
private placement units, or 596,200 private placement units if the Underwriters exercise their over-allotment option in full (the “Private
Placement Units”) of the Company for a purchase price of $10.00 per Private Placement Unit, each Private Placement Unit comprised
of one share of common stock of the Company, par value $0.0001 per share (“Common Stock”), and one warrant to purchase
three-fourths of one share of Common Stock (each whole warrant, a “Warrant”) at the consummation of the Business Combination
(as defined below). The shares of Common Stock underlying the Private Warrants (as defined below) are hereinafter referred to as the “Warrant
Shares.” The shares of Common Stock underlying the Private Placement Units (excluding the Warrant Shares) are hereinafter referred
to as the “Private Shares.” The Warrants underlying the Private Placement Units are hereinafter referred to as the
 “Private Warrants.” The Private Placement Units, the Private Shares, the Private Warrants, and the Warrant Shares collectively,
are hereinafter referred to as the “Securities.” Each Private Warrant is exercisable to purchase three-fourths share
of Common Stock at an exercise price of $11.50 per whole share, subject to the adjustments as set forth in the Warrant Agreement (as defined
below), during the period commencing on the later of (i) twelve (12) months from the date of the closing of the Company’s initial
public offering of units (the “IPO”) and (ii) the consummation of the Company’s initial business combination
(the “Business Combination”), as such term is defined in the registration statement in connection with the IPO, as
amended at the time it becomes effective (the “Registration Statement”), filed with the Securities and Exchange Commission
(“SEC”), and expiring on the fifth anniversary of the consummation of the Business Combination (provided that so long
as the Private Warrants are held by the Subscriber, its designees or affiliates, the Subscriber, its designees or affiliates will not
be permitted to exercise such Private Warrants after the five year anniversary of the effective date of the Registration Statement); and

 

WHEREAS, the each of the Subscribers
severally agrees to purchase, the number of private placement units set forth opposite the respective Subscriber’s name on Schedule
I hereof for an aggregate of 551,200 Private Placement Units for the Purchase Price (as defined below), and the Company wishes to accept
such subscription from the Subscriber.

 

NOW, THEREFORE, in consideration
of the premises and the mutual covenants hereinafter set forth and other good and valuable consideration, the receipt and sufficiency
of which are hereby acknowledged, the Company and the Subscriber hereby agree as follows:

 

1.                  
Agreement to Subscribe.

 

1.1               
Purchase and Issuance of the Private Placement Units. Upon the terms and subject to the conditions of this Agreement, the
Subscriber hereby agrees to purchase from the Company, and the Company hereby agrees to sell to the Subscriber, on the Closing Date (as
defined below) the Private Placement Units in consideration of the payment of the Purchase Price. On the Closing Date, the Company shall,
at its option, deliver to the Subscriber the certificates representing the Securities purchased or effect such delivery in book-entry
form.

 

1.2               
Purchase Price. As payment in full for the Private Placement Units being purchased under
this Agreement, each Subscriber shall pay $10.00 per Private Placement Unit, for an aggregate of $5,512,000, or $5,962,000 if the over-allotment
option is exercised in full (the “Purchase Price”) by wire transfer of immediately available funds or by such other
method as may be reasonably acceptable to the Company, to the trust account (the “Trust Account”) at a financial institution
to be chosen by the Company, maintained by American Stock Transfer & Trust Company, LLC, acting as trustee (“AST”),
on or prior to the Closing Date.

 

     

     

    

 

1.3               
 Closing. The closing of the purchase and sale of the Private Placement Units (the “Closing”) shall take
place simultaneously with the closing of the IPO on the date of the closing of the IPO (the “Closing Date”).

 

1.4               
Conditions to Closing. The obligation of the Subscriber to purchase and pay for the Private Placement Units as provided
herein shall be subject to the satisfaction of the conditions set forth in Section 4 of the Underwriting Agreement, dated the date hereof
(the “Underwriting Agreement”), by and among the Company, the Subscriber and A.G.P./Alliance Global Partners.

 

1.5               
Termination. This Agreement and each of the obligations of the undersigned shall be null and void and without effect if
the Closing does not occur on prior to [●], 2021 or if the Underwriting Agreement is terminated for any reason.

 

2.                  
Representations and Warranties of the Subscriber.

 

Subscriber represents and
warrants to the Company that:

 

2.1               
No Government Recommendation or Approval. Subscriber understands that no federal or state agency has passed upon or made
any recommendation or endorsement of the Company or the Sale of the Securities.

 

2.2               
Accredited Investor. Subscriber represents that it is an “accredited investor” as such term is defined in Rule
501(a) of Regulation D under the Securities Act of 1933, as amended (the “Securities Act”), and acknowledges that the
sale contemplated hereby is being made in reliance, among other things, on a private placement exemption to “accredited investors”
under the Securities Act and similar exemptions under state law.

 

2.3               
Intent. Subscriber is purchasing the Securities solely for investment purposes, for Subscriber’s own account (and/or
for the account or benefit of its members or affiliates, as permitted, pursuant to the terms hereof), and not with a view to the distribution
thereof and Subscriber has no present arrangement to sell the Securities to or through any person or entity except as may be permitted
hereunder. The Subscriber shall not engage in hedging transactions with regard to the Securities unless in compliance with the Securities
Act.

 

2.4               
Restrictions on Transfer. Subscriber acknowledges and understands the Private Placement Units are being offered in a transaction
not involving a public offering in the United States within the meaning of the Securities Act. The Securities have not been registered
under the Securities Act and, if in the future Subscriber decides to offer, resell, pledge or otherwise transfer the Securities, such
Securities may be offered, resold, pledged or otherwise transferred only pursuant to (i) an effective registration statement filed under
the Securities Act, (ii) an exemption from registration under Rule 144 promulgated under the Securities Act, if available, or (iii) any
other available exemption from the registration requirements of the Securities Act, and in each case in accordance with any applicable
securities laws of any state or any other jurisdiction. Notwithstanding the foregoing, Subscriber acknowledges and understands the Securities
are subject to transfer restrictions as described in Section 7 hereof. Subscriber agrees that if any transfer of its Securities or any
interest therein is proposed to be made, as a condition precedent to any such transfer, Subscriber may be required to deliver to the Company
an opinion of counsel satisfactory to the Company with respect to such transfer. Absent registration or another available exemption from
registration, Subscriber agrees it will not resell the Securities (unless otherwise permitted pursuant to the terms hereof). Subscriber
further acknowledges that because the Company is a shell company, Rule 144 may not be available to Subscriber for the resale of the Securities
until the one year anniversary following consummation of the Business Combination of the Company, despite technical compliance with the
requirements of Rule 144 and the release or waiver of any contractual transfer restrictions.

 

2.5               
Sophisticated Investor.

 

(a)                
Subscriber is sophisticated in financial matters and is able to evaluate the risks and benefits of the investment in the Securities.

 

    2

     

    

 

(b)               
 Subscriber is aware that an investment in the Securities is highly speculative and subject to substantial risks because, among
other things, (i) the Securities are subject to transfer restrictions and have not been registered under the Securities Act and therefore
cannot be sold unless subsequently registered under the Securities Act or an exemption from such registration is available and (ii) Subscriber
has waived its redemption rights with respect to the Securities as set forth in Section 5 hereof, and the Securities held by the Subscriber
are not entitled to, and have no right, interest or claim to any monies held in the Trust Account, and accordingly Subscriber may suffer
a loss of a portion or all of its investment in the Securities. Subscriber is able to bear the economic risk of its investment in the
Securities for an indefinite period of time.

 

2.6               Organization
and Authority. Subscriber is duly organized, validly existing and in good standing under the laws of its state of incorporation or
formation and it possesses all requisite power and authority necessary to carry out the transactions contemplated by this Agreement.

 

2.7               Authority.
This Agreement has been validly authorized, executed and delivered by Subscriber and is a valid and binding agreement enforceable in
accordance with its terms, subject to the general principles of equity and to bankruptcy or other laws affecting the enforcement of creditors’
rights generally.

 

2.8               No
Conflicts. The execution, delivery and performance of this Agreement and the consummation by Subscriber of the transactions contemplated
hereby do not violate, conflict with or constitute a default under (i) Subscriber’s charter documents, (ii) any agreement or instrument
to which Subscriber is a party or (iii) any law, statute, rule or regulation to which Subscriber is subject, or any agreement, order,
judgment or decree to which Subscriber is subject.

 

2.9               No
Legal Advice from Company. Subscriber acknowledges it has had the opportunity to review this Agreement and the transactions contemplated
by this Agreement and the other agreements entered into between the parties hereto with Subscriber’s own legal counsel and investment
and tax advisors. Except for any statements or representations of the Company made in this Agreement and the other agreements entered
into between the parties hereto, Subscriber is relying solely on such counsel and advisors and not on any statements or representations
of the Company or any of its representatives or agents for legal, tax or investment advice with respect to this investment, the transactions
contemplated by this Agreement or the securities laws of any jurisdiction.

 

2.10            
Reliance on Representations and Warranties. The Subscriber understands the Private Placement Units are being offered and
sold to the Subscriber in reliance on exemptions from the registration requirements under the Securities Act, and analogous provisions
in the laws and regulations of various states, and that the Company is relying upon the truth and accuracy of the representations, warranties,
agreements, acknowledgments and understandings of the Subscriber set forth in this Agreement in order to determine the applicability of
such provisions.

 

2.11            
No General Solicitation. Subscriber is not subscribing for the Private Placement Units as a result of or subsequent to any
general solicitation or general advertising, including but not limited to any advertisement, article, notice or other communication published
in any newspaper, magazine, or similar media or broadcast over television or radio, or presented at any seminar or meeting or in the Registration
Statement.

 

2.12            
Legend. Subscriber acknowledges and agrees the book-entries evidencing each of the Securities shall bear a restrictive legend
(the “Legend”), in form and substance substantially as set forth in Section 4 hereof.

 

3.                  
Representations, Warranties and Covenants of the Company.

 

The Company represents and
warrants to, and agrees with, Subscriber that:

 

3.1               
Valid Issuance of Capital Stock. The total number of shares of all classes of capital stock which the Company has authority
to issue is 50,000,000 shares of Common Stock. As of the date hereof, the Company has issued and outstanding 4,312,500 shares of Common
Stock (of which up to 562,500 shares are subject to forfeiture as described in the Registration
Statement). All of the issued shares of capital stock of the Company have been duly authorized, validly issued, and are fully paid and
non-assessable.

 

    3

     

    

 

3.2               
Title to Securities. Upon issuance in accordance with, and payment pursuant to, the terms hereof and that certain warrant
agreement (the “Warrant Agreement”) to be entered into between the Company and AST, as warrant agent, each of the Private
Placement Units, Private Shares, Private Warrants, and Warrant Shares will be duly and validly issued, fully paid and non-assessable.
On the date of issuance of the Private Placement Units and Warrant Shares shall have been reserved for issuance. Upon issuance in accordance
with, and payment pursuant to, the terms hereof and the Warrant Agreement Subscriber will have or receive good title to the Private Placement
Units, Private Shares and Private Warrants free and clear of all liens, claims and encumbrances of any kind, other than (i) transfer restrictions
hereunder and (ii) transfer restrictions under federal and state securities laws.

 

3.3               
Organization and Qualification. The Company is a corporation duly incorporated, validly existing and in good standing under
the laws of the State of Delaware and has the requisite corporate power to own its properties and assets and to carry on its business
as now being conducted.

 

3.4               
Authorization; Enforcement. (i) The Company has the requisite corporate power and authority to enter into and perform its
obligations under this Agreement and to issue the Securities in accordance with the terms hereof, (ii) the execution, delivery and performance
of this Agreement by the Company and the consummation by it of the transactions contemplated hereby have been duly authorized by all necessary
corporate action, and no further consent or authorization of the Company or its Board of Directors or stockholders is required, and (iii)
this Agreement constitutes valid and binding obligations of the Company enforceable against the Company in accordance with its terms,
except as such enforceability may be limited by applicable bankruptcy, insolvency, fraudulent conveyance, moratorium, reorganization,
or similar laws relating to, or affecting generally the enforcement of, creditors’ rights and remedies or by equitable principles
of general application and except as enforcement of rights to indemnity and contribution may be limited by federal and state securities
laws or principles of public policy.

 

3.5               
No Conflicts. The execution, delivery and performance of this Agreement and the consummation by the Company of the transactions
contemplated hereby do not (i) result in a violation of the Company’s certificate of incorporation or by-laws, (ii) conflict with,
or constitute a default under any agreement or instrument to which the Company is a party or (iii) any law statute, rule or regulation
to which the Company is subject or any agreement, order, judgment or decree to which the Company is subject. Other than any SEC or state
securities filings which may be required to be made by the Company subsequent to the Closing Date, and any registration statement which
may be filed pursuant thereto, the Company is not required under federal, state or local law, rule or regulation to obtain any consent,
authorization or order of, or make any filing or registration with, any court or governmental agency or self-regulatory entity in order
for it to perform any of its obligations under this Agreement or issue the Private Placement Units, Private Shares, Private Warrants or
Warrant Shares in accordance with the terms hereof.

 

3.6               
Additional Representations and Warranties. The representations and warranties of the Company set forth in the Underwriting
Agreement are hereby incorporated herein and are true and correct with the same force and effect as though expressly made herein as of
the date hereof.

 

4.                  
Legends.

 

4.1               
Legend. The Company will issue the Private Placement Units, Private Shares and Private Warrants, and when issued, the Warrant
Shares, purchased by the Subscriber in the name of the Subscriber. The Securities will bear the following Legend and appropriate “stop
transfer” instructions:

 

“THE
SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES
ACT”), OR ANY STATE SECURITIES LAWS AND NEITHER THE SECURITIES NOR ANY INTEREST THEREIN MAY BE OFFERED, SOLD, TRANSFERRED,
PLEDGED OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR SUCH LAWS OR AN
EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT AND SUCH LAWS WHICH, IN THE OPINION OF COUNSEL FOR THIS CORPORATION, IS
AVAILABLE.”

 

    4

     

    

 

“THE SECURITIES
REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO LOCKUP PURSUANT TO A PRIVATE PLACEMENT UNIT SUBSCRIPTION AGREEMENT BETWEEN MOUNT RAINIER
ACQUISITION CORP. AND DC RAINIER SPV LLC AND MAY ONLY BE OFFERED, SOLD, TRANSFERRED, PLEDGED OR OTHERWISE DISPOSED DURING THE TERM OF
THE LOCKUP PURSUANT TO THE TERMS SET FORTH IN THE UNIT SUBSCRIPTION AGREEMENT.”

 

4.2               
Subscriber’s Compliance. Nothing in this Section 4 shall affect in any way the Subscriber’s obligations and
agreements to comply with all applicable securities laws upon resale of the Securities.

 

4.3               
Company’s Refusal to Register Transfer of the Securities. The Company shall refuse to register any transfer of the
Securities, if in the sole judgment of the Company such purported transfer would not be made (i) pursuant to an effective registration
statement filed under the Securities Act, or pursuant to an available exemption from the registration requirements of the Securities Act
and (ii) in compliance herewith.

 

4.4               
Registration Rights. The Subscriber will be entitled to certain registration rights which will be governed by a registration
rights agreement (“Registration Rights Agreement”) to be entered into among the Subscriber, the Company and others,
on or prior to the effective date of the Registration Statement.

 

5.                  
Waiver of Liquidation Distributions.

 

In connection with the Securities
purchased pursuant to this Agreement, Subscriber hereby waives any and all right, title, interest or claim of any kind in or to any distributions
of the amounts in the Trust Account with respect to the Securities, whether (i) in connection with the exercise of redemption rights if
the Company consummates the Business Combination, (ii) in connection with any tender offer conducted by the Company prior to a Business
Combination, (iii) upon the Company’s redemption of shares of Common Stock sold in the Company’s IPO upon the Company’s
failure to timely complete the Business Combination or (iv) in connection with a stockholder vote to approve an amendment to the Company’s
amended and restated certificate of incorporation, (A) to modify the substance or timing of the Company’s obligation to redeem 100%
of the Company’s public shares if the Company does not timely complete the Business Combination or (B) with respect to any other
provision relating to stockholders’ rights or pre-Business Combination activity. In the event Subscriber purchases shares of Common
Stock in the IPO or in the aftermarket, any additional shares so purchased shall be eligible to receive the redemption value of such shares
of Common Stock upon the same terms offered to all other purchasers of Common Stock in the IPO in the event the Company fails to consummate
the Business Combination.

 

6.                  Terms
of Private Warrants. Each Private Warrant shall have the terms set forth in the Warrant Agreement.

 

7.                  Lock-Up
Period.

 

7.1               
The Subscriber agrees that it shall not Transfer any Securities until 30 days after the completion of the Business Combination;
provided, however, that Transfers of Securities are permitted (i) to our or our Sponsor’s officers, directors, consultants or their
affiliates, (ii) in the case of an entity, to its members upon its liquidation, (iii) in the case of an individual, to relatives and trusts
for estate planning purposes, (iv) in the case of an individual, by virtue of the laws of descent and distribution upon death, (v) in
the case of an individual, pursuant to a qualified domestic relations order, (vi) to us for no value for cancellation in connection with
the consummation of our initial business combination, (vii) in connection with the consummation of a business combination at negotiated
prices, or (viii) by virtue of the laws of Delaware or our sponsor’s limited liability company agreement upon dissolution of our
sponsor in each case (except for clause (vi) or (viii) or with our prior consent) where these permitted transferees must enter into a
written agreement agreeing to be bound by the Transfer restrictions these transfer restrictions herein.

 

    5

     

    

 

7.2               
 For purposes of Section 7.1, the term “Transfer” shall mean the (i) sale of, offer to sell, contract or agreement
to sell, hypothecate, pledge, grant of any option to purchase or otherwise dispose of or agreement to dispose of, directly or indirectly,
or establishment or increase of a put equivalent position or liquidation with respect to or decrease of a call equivalent position within
the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, and the rules and regulations of the SEC promulgated thereunder
with respect to, any of the Securities, (ii) entry into any swap or other arrangement that transfers to another, in whole or in part,
any of the economic consequences of ownership of any of the Securities, whether any such transaction is to be settled by delivery of such
Securities, in cash or otherwise, or (iii) public announcement of any intention to effect any transaction specified in clause (i) or (ii).

 

8.                  
Terms of the Private Placement Units and Private Warrants.

 

8.1               The
Private Placement Units and their component parts are substantially identical to the units to be offered in the IPO except that: (i)
the Private Placement Units and component parts are subject to the transfer restrictions described in Section 7 hereof, and (ii) the
Private Placement Units and component parts are being purchased pursuant to an exemption from the registration requirements of the Securities
Act and will become freely tradable only after the expiration of the lockup described above in clause (i) and they are registered pursuant
to the Registration Rights Agreement or an exemption from registration is available, and the restrictions described above in clause (i)
has expired.

 

8.2               Subscriber
agrees that if the Company seeks stockholder approval of a Business Combination, then in connection with such Business Combination, Subscriber
shall (i) vote the Private Shares owned by it in favor of the Business Combination and (ii) not redeem any Private Shares owned by Subscriber
in connection with such stockholder approval.

 

9.                  
Governing Law; Jurisdiction; Waiver of Jury Trial.

 

This Agreement shall be governed
by and construed in accordance with the laws of the State of New York for agreements made and to be wholly performed within such state.
The parties hereto hereby waive any right to a jury trial in connection with any litigation pursuant to this Agreement and the transactions
contemplated hereby.

 

10.               
Assignment; Entire Agreement; Amendment.

 

10.1            
Assignment. Neither this Agreement nor any rights hereunder may be assigned by any party to any other person other than by Subscriber
to a person agreeing to be bound by the terms hereof, including the transfer restrictions contained in Section 7 hereof.

 

10.2            
Entire Agreement. This Agreement sets forth the entire agreement and understanding between the parties as to the subject matter
thereof and merges and supersedes all prior discussions, agreements and understandings of any and every nature among them.

 

10.3            
Amendment. Except as expressly provided in this Agreement, neither this Agreement nor any term hereof may be amended, waived, discharged
or terminated other than by a written instrument signed by all of the parties hereto.

 

10.4            
Binding upon Successors. This Agreement shall be binding upon and inure to the benefit of the parties hereto and to their respective
heirs, legal representatives, successors and permitted assigns.

 

11.               
Notices.

 

11.1             Notices.
Unless otherwise provided herein, any notice or other communication to a party hereunder shall be sufficiently given if in writing
and personally delivered or sent by facsimile or other electronic transmission with copy sent in another manner herein provided or
sent by courier (which for all purposes of this Agreement shall include Federal Express or other recognized overnight courier) or
mailed to said party by certified mail, return receipt requested, at its address provided for herein or such other address as either
may designate for itself in such notice to the other. Communications shall be deemed to have been received when delivered
personally, on the scheduled arrival date when sent by next day or 2nd-day courier service, or if sent by facsimile upon receipt of
confirmation of transmittal or, if sent by mail, then three days after deposit in the mail. If given by electronic transmission,
such notice shall be deemed to be delivered (i) if by electronic mail, when directed to an electronic mail address at which the
stockholder has consented to receive notice; (ii) if by a posting on an electronic network together with separate notice to the
stockholder of such specific posting, upon the later of (1) such posting and (2) the giving of such separate notice; and (iii) if by
any other form of electronic transmission, when directed to the stockholder.

 

    6

     

    

 

12.               
Counterparts; Electronic Signatures.

 

This Agreement may be
executed in counterparts, each of which when so executed shall be deemed to be an original and all of which when taken together shall
constitute one and the same instrument. The words “execution,” signed,” “signature,” and words of like
import in this Agreement or in any other certificate, agreement or document related to this Agreement shall include images of manually
executed signatures transmitted by facsimile or other electronic format (including, without limitation, “pdf,” “tif”
or “jpg”) and other electronic signatures (including, without limitation, DocuSign and AdobeSign). The use of electronic
signatures and electronic records (including, without limitation, any contract or other record created, generated, sent, communicated,
received, or stored by electronic means) shall be of the same legal effect, validity and enforceability as a manually executed signature
or use of a paper-based record-keeping system to the fullest extent permitted by applicable law, including the Federal Electronic Signatures
in Global and National Commerce Act, the New York State Electronic Signatures and Records Act and any other applicable law, including,
without limitation, any state law based on the Uniform Electronic Transactions Act or the Uniform Commercial Code.

 

13.               
Survival; Severability.

 

13.1            
Survival. The representations, warranties, covenants and agreements of the parties hereto shall survive the Closing Date.

 

13.2            
Severability. In the event that any provision of this Agreement becomes or is declared by a court of competent jurisdiction to
be illegal, unenforceable or void, this Agreement shall continue in full force and effect without said provision; provided that no such
severability shall be effective if it materially changes the economic benefit of this Agreement to any party.

 

14.               
Headings.

 

The titles and subtitles used
in this Agreement are used for convenience only and are not to be considered in construing or interpreting this Agreement.

 

[remainder of page intentionally left blank]

 

    7

     

    

 

IN WITNESS WHEREOF, the parties
hereto have executed this Agreement to be effective as of the date first set forth above.

 

	 	COMPANY:
	 	 
	 	MOUNT RAINIER ACQUISITION CORP.
	 	 
	 	By:	 
	 	 	Name: Matthew Kearney
	 	 	Title: Chief Executive Officer

 

	 	SUBSCRIBER:
	 	 
	 	DC RAINIER SPV LLC
	 	By:
    Dominion Capital LLC, its Manager
	 	By: Dominion Capital Holdings LLC, its
    Manager
	 	 
	 	 	By:	       
	 	 	Name:
	 	 	Title:

 

	 	Number
    of Private Placement Units: ______________
	 	 
	 	 
	 	Matthew Kearney
	 	Number of Private Placement Units: _________
	 	 
	 	 
	 	Young Cho
	 	Number of Private Placement Units: _________

 

[Signature Page to Private Placement Unit Subscription
Agreement]

 

     

     

    

 

Schedule I

Schedule of Subscribers

 

	Subscriber Name:	Notice Information:	Number of Private Placement Units:	Purchase Price
	DC Rainer SPV LLC	 	 	 
	Matthew Kearney	 	 	 
	Young Cho	 	 	 
	 	 	Total: 551,200	$5,512,000

 

    9Exhibit 10.6

STOCK ESCROW AGREEMENT

 

This STOCK ESCROW AGREEMENT,
dated as of [●], 2021 (“Agreement”), by and among MOUNT RAINIER ACQUISITION CORP., a Delaware corporation (“Company”)
and the initial stockholders listed on the signature pages hereto (collectively, the “Initial Stockholders”) and AMERICAN
STOCK TRANSFER & TRUST COMPANY, LLC, a New York limited liability trust company (“Escrow Agent”).

 

WHEREAS, the Company has entered
into an Underwriting Agreement, dated as of [●], 2021 (“Underwriting Agreement”), with A.G.P./Alliance Global Partners,
as representative of the underwriters ( the “Underwriters”), pursuant to which, among other matters, the Underwriters have
agreed to purchase 15,000,000 units (“Units”) of the Company, plus an additional 2,250,000 Units if the Underwriters exercise
their over-allotment option in full. Each Unit consists of one share of common stock of the Company, par value $0.0001 per share (the
 “Common Stock”), and one warrant, with each warrant entitling the holder thereof to purchase three-fourths of one share of
the Common Stock at an exercise price of $11.50 per whole share, all as more fully described in the Company’s final Prospectus,
dated [●], 2021 (“Prospectus”), comprising part of the Company’s Registration Statement on Form S-1 (File No.
333-256816) under the Securities Act of 1933, as amended (“Registration Statement”), declared effective on [●], 2021
(“Effective Date”).

 

WHEREAS, the Initial Stockholders
have agreed as a condition of the sale of the Units to deposit their “founder shares” (as defined in the Prospectus), as set
forth opposite their respective names on Exhibit A attached hereto (collectively “Escrow Shares”), in escrow as hereinafter
provided.

 

WHEREAS, the Company and the
Initial Stockholders desire that the Escrow Agent accept the Escrow Shares, in escrow, to be held and disbursed as hereinafter provided.

 

IT IS AGREED:

 

1. Appointment of Escrow
Agent. The Company and the Initial Stockholders hereby appoint the Escrow Agent to act in accordance with and subject to the terms
of this Agreement and the Escrow Agent hereby accepts such appointment and agrees to act in accordance with and subject to such terms.

 

2. Deposit of Escrow Shares.
On or prior to the date hereof, each of the Initial Stockholders delivered to the Escrow Agent certificates representing such Initial
Stockholder’s respective Escrow Shares, together with applicable share powers, to be held and disbursed subject to the terms and
conditions of this Agreement. Each of the Initial Stockholders acknowledges that the certificate representing such Initial Stockholder’s
Escrow Shares is legended to reflect the deposit of such Escrow Shares under this Agreement.

 

3. Disbursement of the
Escrow Shares.

 

3.1 The Escrow Agent shall
hold the Escrow Shares during the period (the “Escrow Period”) commencing on the date hereof ending on the earlier of
(i) one year after the date of the consummation of the Company’s initial business combination (as described in the
Registration Statement, hereinafter a “Business Combination”) and (ii) the date on which the closing price of the Common
Stock equals or exceeds $12.00 per share (as adjusted for stock splits, stock dividends, stock capitalizations, reorganizations and
recapitalizations) for any 20 trading days within any 30-trading day period commencing at least 150 following the closing of the
Company’s initial Business Combination. The Company shall promptly provide notice of the consummation of a Business
Combination to the Escrow Agent. Upon completion of the Escrow Period, the Escrow Agent shall disburse such amount of each Initial
Stockholder’s Escrow Shares (and any applicable share power) to such Initial Stockholder; provided, however, that if the
Escrow Agent is notified by the Company pursuant to Section 6.7 hereof that the Company is being liquidated at any time during the
Escrow Period, then the Escrow Agent shall promptly destroy the certificates representing the Escrow Shares; provided further,
however, that if, after the Company consummates an initial Business Combination, the Company (or the surviving entity) subsequently
consummates a liquidation, merger, stock exchange or other similar transaction which results in all of the stockholders of such
entity having the right to exchange their shares of Common Stock for cash, securities or other property, then the Escrow Agent will,
upon receipt of a notice executed by the Chairman of the Board, Chief Executive Officer or other authorized officer of the Company,
in form reasonably acceptable to the Escrow Agent, certifying that such transaction is then being consummated or such conditions
have been achieved, as applicable, release the Escrow Shares to the Initial Stockholders. The Escrow Agent shall have no further
duties hereunder after the disbursement or destruction of the Escrow Shares in accordance with this Section 3.1.

 

     

     

    

 

3.2 Notwithstanding
Section 3.1, if the Underwriters do not exercise their over-allotment
option to purchase an additional 2,250,000 Units of the Company in full within 45 days of the date of the Prospectus (as described in
the Underwriting Agreement), the Initial Stockholders agree that the Escrow Agent shall return to the Company for cancellation, at no
cost, the number of Escrow Shares held by the Initial Stockholders listed on Exhibit B determined by multiplying (a) the product
of (i) 562,500 multiplied by (ii) a fraction, (x) the numerator of which is the number of Escrow Shares held by each such holder, and
(y) the denominator of which is the total number of Escrow Shares, by (b) a fraction, (i) the numerator of which is 2,250,000 minus the
number of Units purchased by the Underwriters upon the exercise of their over-allotment option, and (ii) the denominator of which is 2,250,000,
without taking into account the transfer of an aggregate amount of 350,000 representative shares (400,000 shares if the over-allotment
option is exercised in full) from A.G.P./Alliance Global Partners to the sponsor that took place pursuant to the side letters dates as
of September 27, 2021 and September 30, 2021. The Company shall promptly provide notice to the Escrow Agent of the expiration or termination
of the Underwriters’ over-allotment option and the number of Units, if any, purchased by the Underwriters in connection with their
exercise thereof.

 

4. Rights of Initial Stockholders
in Escrow Shares.

 

4.1 Voting Rights as a Stockholder.
Subject to the terms of the Insider Letters (as defined below) described in Section 4.4 hereof and except as herein provided, the Initial
Stockholders shall retain all of their rights as stockholders of the Company during the Escrow Period, including, without limitation,
the right to vote such shares.

 

4.2 Dividends and Other Distributions
in Respect of the Escrow Shares. During the Escrow Period, all dividends payable in cash with respect to the Escrow Shares shall be
paid to the Initial Stockholders, but all dividends payable in stock or other non-cash property (“Non-Cash Dividends”) shall
be delivered to the Escrow Agent to hold in accordance with the terms hereof. As used herein, the term “Escrow Shares” shall
be deemed to include the Non-Cash Dividends distributed thereon, if any.

 

4.3 Restrictions on Transfer.
During the Escrow Period, the only permitted transfers of the Escrow Shares will be (1) to any persons or entities (including their affiliates
and stockholders) participating in the private placement of the “private warrants” (as defined in the Prospectus), and officers,
directors, stockholders, employees and members of the Initial Stockholders and their respective affiliates, (2) amongst the Initial Stockholders
(including, to the extent the Initial Stockholders are entities, to such entity’s members, partners, stockholders or other equity
holders) or to the Company’s officers, directors and employees, (3) if any Initial Stockholder is an entity, as a distribution to
its partners, stockholders, or members upon its liquidation, (4) by bona fide gift to a member of the Initial Stockholder’s (or
its permitted transferee’s) immediate family or to a trust, the beneficiary of which is the Initial Stockholder (or its permitted
transferee) or a member of the Initial Stockholder’s (or its permitted transferee’s) immediate family, for estate planning
purposes, (5) by virtue of the laws of descent and distribution upon death, (6) pursuant to a qualified domestic relations order, (7)
by certain pledges to secure obligations incurred in connection with purchases of the Company’s securities, (8) by private sales
at prices no greater than the price at which the founder shares were originally purchased or (9) for the cancellation of up to 562,500
shares of Common Stock subject to forfeiture to the extent that the Underwriters’ over-allotment is not exercised in full or in
part or in connection with the consummation of the Company’s initial business combination, in each case (except for clause 9 or
with the Company’s prior consent) where such permitted transferee agrees to the terms of this Agreement and the Insider Letter (as
defined below).

 

4.4 Insider Letters.
Each of the Initial Stockholders has executed a letter agreement with the Representatives and the Company, dated as indicated on Exhibit
C hereto, and the form of which is filed as an exhibit to the Registration Statement (“Insider Letter”), respecting the
rights and obligations of such Initial Stockholder in certain events, including but not limited to the liquidation of the Company.

 

    2

     

    

 

5. Concerning the Escrow
Agent.

 

5.1 Good Faith Reliance.
The Escrow Agent shall not be liable for any action taken or omitted by it in good faith and in the exercise of its own best judgment,
and may rely conclusively and shall be protected in acting upon any order, notice, demand, certificate, opinion or advice of counsel (including
counsel chosen by the Escrow Agent), statement, instrument, report or other paper or document (not only as to its due execution and the
validity and effectiveness of its provisions, but also as to the truth and acceptability of any information therein contained) which is
believed by the Escrow Agent to be genuine and to be signed or presented by the proper person or persons. The Escrow Agent shall not be
bound by any notice or demand, or any waiver, modification, termination or rescission of this Agreement unless evidenced by a writing
delivered to the Escrow Agent signed by the proper party or parties and, if the duties or rights of the Escrow Agent are affected, unless
it shall have given its prior written consent thereto.

 

5.2 Indemnification.
The Escrow Agent shall be indemnified and held harmless by the Company from and against any expenses, including reasonable counsel
fees and disbursements, or loss suffered by the Escrow Agent in connection with any action, suit or other proceeding involving any
claim which in any way, directly or indirectly, arises out of or relates to this Agreement, the services of the Escrow Agent
hereunder, or the Escrow Shares held by it hereunder, other than expenses or losses arising from the gross negligence or willful
misconduct of the Escrow Agent (as determined by a court of competent jurisdiction in a final and non-appealable decision). Promptly after the receipt by the Escrow Agent of notice of any demand or claim or the commencement
of any action, suit or proceeding, the Escrow Agent shall notify the other parties hereto in writing. In the event of the receipt of
such notice, the Escrow Agent, in its sole discretion, may commence an action in the nature of interpleader in an appropriate court
to determine ownership or disposition of the Escrow Shares or it may deposit the Escrow Shares with the clerk of any appropriate
court or it may retain the Escrow Shares pending receipt of a final, non-appealable order of a court having jurisdiction over all of
the parties hereto directing to whom and under what circumstances the Escrow Shares are to be disbursed and delivered. The
provisions of this Section 5.2 shall survive in the event the Escrow Agent resigns or is discharged pursuant to Sections 5.5 or 5.6
below.

 

5.3 Compensation. The
Escrow Agent shall be entitled to reasonable compensation from the Company for all services rendered by it hereunder. The Escrow Agent
shall also be entitled to reimbursement from the Company for all expenses paid or incurred by it in the administration of its duties hereunder
including, but not limited to, all counsel, advisors’ and agents’ fees and disbursements and all taxes or other governmental
charges.

 

5.4 Further Assurances.
From time to time on and after the date hereof, the Company and the Initial Stockholders shall deliver or cause to be delivered to the
Escrow Agent such further documents and instruments and shall do or cause to be done such further acts as the Escrow Agent shall reasonably
request to carry out more effectively the provisions and purposes of this Agreement, to evidence compliance herewith or to assure itself
that it is protected in acting hereunder.

 

5.5 Resignation. The
Escrow Agent may resign at any time and be discharged from its duties as escrow agent hereunder by its giving the other parties hereto
written notice and such resignation shall become effective as hereinafter provided. Such resignation shall become effective at such time
that the Escrow Agent shall turn over to a successor escrow agent appointed by the Company, the Escrow Shares held hereunder. If no new
escrow agent is so appointed within the 90 day period following the giving of such notice of resignation, the Escrow Agent may deposit
the Escrow Shares with any court it reasonably deems appropriate.

 

5.6 Discharge of Escrow Agent.
The Escrow Agent shall resign and be discharged from its duties as escrow agent hereunder if so requested in writing at any time by the
other parties hereto, jointly, provided, however, that such resignation shall become effective only upon acceptance of appointment by
a successor escrow agent as provided in Section 5.5.

 

5.7 Liability. Notwithstanding
anything herein to the contrary, the Escrow Agent shall not be relieved from liability hereunder for its own gross negligence or its own
willful misconduct (as determined by a court of competent jurisdiction in a final and non-appealable decision). 

 

5.8 Waiver. The
Escrow Agent hereby waives any right of set-off or any other right, title, interest or claim of any kind (“Claim”) in,
or to any distribution of, the Trust Account (as defined in that certain Investment Management Trust Agreement, dated as of the date
hereof, by and between the Company and the Escrow Agent as trustee thereunder) and hereby agrees not to seek recourse,
reimbursement, payment or satisfaction for any Claim against the Trust Account for any reason whatsoever.

 

    3

     

    

 

6. Miscellaneous.

 

6.1 Governing Law. This
Agreement shall for all purposes be deemed to be made under and shall be construed in accordance with the laws of the State of New York,
without giving effect to conflicts of law principles that would result in the application of the substantive laws of another jurisdiction.

 

6.2 Third Party Beneficiaries.
Each of the Initial Stockholders hereby acknowledges that each of the Representatives is a third party beneficiary of this Agreement and
this Agreement may not be modified or changed without the prior written consent of the Representatives.

 

6.3 Entire Agreement.
This Agreement contains the entire agreement of the parties hereto with respect to the subject matter hereof and, except as expressly
provided herein, may not be changed or modified except by an instrument in writing signed by the party to the charged.

 

6.4 Headings. The headings
contained in this Agreement are for reference purposes only and shall not affect in any way the meaning or interpretation thereof.

 

6.5 Binding Effect. This
Agreement shall be binding upon and inure to the benefit of the respective parties hereto and their legal representatives, successors
and assigns; provided, that the Escrow Agent may not assign this Agreement without the prior written consent of the Company.

 

6.6 Notices. Any notice
or other communication required or which may be given hereunder shall be in writing and either be delivered personally or be mailed, certified
or registered mail, or by private national courier service, return receipt requested, postage prepaid, or by e-mail as described below,
and shall be deemed given when so delivered personally or by e-mail or, if mailed or sent by private national courier service, two days
after the date of mailing or the date of delivery to the private national courier service, as follows:

 

If to the Company or a Stockholder,
to: 

 

Mount Rainier Acquisition Corp.

256 W. 38th Street, 15th Floor

New York, NY 10018

Attn: Matthew
Kearney

 

Copy (which copy
shall not constitute notice) to:

 

Loeb & Loeb LLP

345 Park Avenue

New York, New York 10154

Attn: Mitchell Nussbaum, Esq.

Email: 

 

and if to the Escrow Agent, to:

 

American Stock Transfer & Trust
Company, LLC

201 15th Avenue |

Brooklyn, NY 11219

		Attn:	

 

    4

     

    

 

A copy (which copy shall not constitute
notice) sent hereunder shall be sent to:

 

A.G.P./Alliance
Global Partners

590 Madison Avenue, 28th Floor 

New York, NY 10022

Attn: Thomas J. Higgins

Email: 

 

and:  Manatt,
Phelps & Phillips LLP

695 Town Center Drive, 14th Floor

Costa Mesa, California 92626

Attn: Thomas J. Poletti

Email: 

 

The parties hereto consent
to the delivery of notices or other communication by electronic transmission at the e-mail address set forth below the respective party’s
name in Section 6.6 hereto. To the extent that any notice given by means of electronic transmission is returned or undeliverable for any
reason, the foregoing consent shall be deemed to have been revoked until a new or corrected e-mail address has been provided, and such
attempted electronic notice shall be ineffective and deemed to not have been given. Each party agrees to promptly notify the other parties
of any change in its e-mail address, and that failure to do so shall not affect the foregoing. The parties may change the persons and
addresses to which the notices or other communications are to be sent by giving written notice to any such change in the manner provided
herein for giving notice.

 

6.7 Liquidation of the Company.
The Company shall give the Escrow Agent written notification of the liquidation and dissolution of the Company in the event that the Company
fails to consummate a Business Combination within the time period specified in the Prospectus.

 

[Signature Page Follows]

 

    5

     

    

 

WITNESS the execution of this
Agreement as of the date first above written.

 

	 	MOUNT RAINIER
    ACQUISITION CORP.
	 	 
	 	By:	 
	 	 	Name: Matthew Kearney
	 	 	Title: Chief Executive Officer
	 	 
	 	AMERICAN STOCK
    TRANSFER & TRUST COMPANY, LLC
	 	 
	 	By:	 
	 		Name:	
	 	 	Title: 	Vice President
	 	 
	 	INITIAL
    STOCKHOLDERS:
	 	 
	 	DC
    RAINIER SPV LLC

	 	By:	 Dominion Capital LLC, its Manager
	 	By: 	Dominion Capital Holdings LLC, its Manager

 

	 	 	By:	                                            
	 	 	Name:	 
	 	 	Title:	 
	 	 	 
	 	 	A.G.P./Alliance
    Global Partners
	 	 	By:
	 	 	 
	 	 	By:	 
	 	 	Name:	 
	 	 	Title:	 
	 	 	 
	 	 	 
	 	 	Matthew
    Kearney
	 	 	 
	 	 	 
	 	 	Young
    Cho
	 	 	 
	 	 	 
	 	 	Otto
    Risbakk
	 	 	 
	 	 	 
	 	 	Christina
    Favilla
	 	 	 
	 	 	 
	 	 	Jeffery
    Bistrong

 

[Signature Page to Escrow
Agreement]

 

     

     

    

 

EXHIBIT A

 

Initial Stockholders; Escrow Shares

 

	Name
    of Initial Stockholders*	 	Number

    of Shares	 	Date
    of

    Insider Letter 
	DC Rainier
    SPV LLC	 	2,901,919	 	 
	A.G.P./Alliance
    Global Partners	 	915,000
	 	 
	Matthew
    Kearney	 	336,985	 	 
	Young
    Cho	 	101,095	 	 
	Otto
    Risbakk	 	19,167	 	 
	Christina
    Favilla	 	19,167	 	 
	Jeffery Bistrong	 	19,167	 	 

 

     

     

    

 

EXHIBIT B

 

Escrow Shares subject to cancellation

 

	DC Rainier SPV LLC	332,859
	A.G.P./Alliance Global Partners	165,000
	Matthew Kearney	43,955
	Young Cho	13,186
	Otto Risbakk	2,500
	Christina Favilla	2,500
	Jeffery Bistrong	2,500

 

     

     

    

 

EXHIBIT C

 

Insider Letter

 

Insider Letter by and between the Company, DC
Rainier SPV LLC, A.G.P./Alliance Global Partners, Matthew Kearney, Young Cho, Otto
Risbakk, Christina Favilla, and Jeffery Bistrong, dated [●], 2021.

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