Document:

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                                                                    Exhibit 4.12
                                   ----------

                                     FORM OF
                             CERTIFICATE OF TRUST OF
                              AMEREN CAPITAL TRUST__

            THIS CERTIFICATE OF TRUST of Ameren Capital Trust (the "Trust"),
dated ______________, 200_, is being duly execute and filed by [Name of
trustee], a Delaware banking corporation, as trustee, to form a business trust
under the Delaware Business Trust Act (12 Del. C. ss. 3801 et seq.).

                                   ----------

            1. Name. The name of the business trust formed hereby is "Ameren
Capital Trust __."

            2. Delaware Trustee. The name and address of the trustee of the
Trust with a principal place of business in the State of Delaware is:

               [Name and address of trustee].

            3. Effective Date. This Certificate of Trust shall be effective upon
its filing with the Secretary of State of the State of Delaware.

            IN WITNESS WHEREOF, the undersigned, being the sole trustee of the
Trust, has executed this Certificate of Trust as of the date first written
above.

                                            [NAME OF TRUSTEE],
                                            not in its individual capacity,
                                            but solely as trustee

                                            By:
                                               ---------------------------------

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                                                                    Exhibit 4.13

                            AMEREN CAPITAL TRUST ___
                             FORM OF TRUST AGREEMENT

      THIS TRUST AGREEMENT, dated as of ____________, 200__, is by and between
(i) Ameren Corporation, a Missouri corporation (the "Depositor"), (ii) [name of
Delaware trustee], a Delaware banking corporation, as Delaware trustee (the
"Delaware Trustee"), and (iii) [name of administrative trustee], as
administrative trustee (the "Administrative Trustee," and together with the
Delaware Trustee, the "Trustees"). The Depositor and the Trustees hereby agree
as follows:

      1. The trust created hereby (the "Trust") shall be known as "Ameren
Capital Trust __."

      2. The Depositor hereby assigns, transfers, conveys and sets over to the
Trust the sum of $10. Such amount shall constitute the initial trust estate. The
Trustees hereby declare that they will hold the trust estate for the Depositor
subject to the terms hereof.

      3. It is the intention of the parties hereto that the Trust created hereby
constitutes a business trust under Chapter 38 of Title 12 of the Delaware Code,
12 Del. C. ss. 3801 (the "Business Trust Act"), and that this document
constitutes the governing instrument of the Trust.

      4. The Trustees are hereby authorized and directed to execute and file a
certificate of trust with the Delaware Secretary of State in accordance with the
provisions of the Business Trust Act.

      5. The Depositor, the Trustees and others will enter into an amended and
restated Trust Agreement, satisfactory to each such party and substantially in
the form to be included as an exhibit to the Registration Statement on Form S-3
(the "1933 Act Registration Statement") referred to below, or in such other form
as the Trustees and the Depositor may approve, to provide for the contemplated
operation of the Trust created hereby and the issuance of Trust Preferred
Securities referred to therein. Prior to the execution and delivery of such
amended and restated Trust Agreement, the Trustees shall not have any duty or
obligation hereunder or with respect to the trust estate, except as otherwise
required by applicable law or as may be necessary to obtain, prior to such
execution and delivery, any licenses, consents or approvals required by
applicable law or otherwise. Notwithstanding the foregoing, the Trustees may
take all actions deemed proper as are necessary to effect the transactions
contemplated herein.

      6. The Depositor and the Trustees hereby authorize and direct the
Depositor, as the sponsor of the Trust, (i) to file with the Securities and
Exchange Commission (the "Commission") and to execute, in the case of the 1933
Act Registration Statement and 1934 Act Registration Statement (as herein
defined), on behalf of the Trust (a) the 1933 Act Registration Statement,
including pre-effective or post-effective amendments to such Registration
Statement, relating to the registration under the Securities Act of 1933, as
amended (the "1933 Act"), of the Trust Preferred Securities of the Trust, (b)
any preliminary prospectus or prospectus or supplement thereto relating to the
Trust Preferred Securities required to be filed pursuant to Rule 424 under the
1933 Act, and (c) a Registration Statement on Form 8-A or other appropriate form
(the "1934 Act Registration Statement") (including all pre-effective and
post-

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effective amendments thereto) relating to the registration of the Trust
Preferred Securities of the Trust under Section 12(b) of the Securities Exchange
Act of 1934, as amended; (ii) to file with any national securities exchange and
execute on behalf of the Trust a listing application and all other applications,
statements, certificates, agreements and other instruments as shall be necessary
or desirable to cause the Trust Preferred Securities to be listed on such
exchange; (iii) to file and execute on behalf of the Trust such applications,
reports, surety bonds, irrevocable consents, appointments of attorney for
service of process and other papers and documents as shall be necessary or
desirable to register the Trust Preferred Securities under the securities or
"Blue Sky" laws of such jurisdictions as the Depositor, on behalf of the Trust,
may deem necessary or desirable; and (iv) to execute, deliver and perform on
behalf of the Trust, an underwriting agreement with the Depositor and the
underwriter or underwriters of the Trust Preferred Securities of the Trust. In
the event that any filing referred to in clauses (i) through (iii) above is
required by the rules and regulations of the Commission, any national securities
exchange or state securities or Blue Sky laws to be executed on behalf of the
Trust by the Trustees, the Trustees, in their capacity as trustees of the Trust,
are hereby authorized and directed to join in any such filing and to execute on
behalf of the Trust any and all of the foregoing, it being understood that [name
of Delaware trustee], in its capacity as trustee of the Trust, shall not be
required to join in any such filing or execute on behalf of the Trust any such
document unless required by the rules and regulations of the Commission, any
national securities exchange or state securities or Blue Sky laws. In connection
with all of the foregoing, each of the Trustees, solely in its capacity as
trustee of the Trust, and the Depositor hereby constitutes and appoints [   ],
and each of them severally, as its true and lawful attorney-in-fact and agent,
with full power of substitution and resubstitution for the Depositor or in the
Depositor's name, place and stead, in any and all capacities, to sign any and
all amendments (including all pre-effective and post-effective amendments) to
the 1933 Act Registration Statement and the 1934 Act Registration Statement and
to file the same, with all exhibits thereto, and any other documents in
connection therewith, with the Commission, granting unto said attorney-in-fact
and agent full power and authority to do and perform each and every act and
thing requisite and necessary to be done in connection therewith, as fully to
all intents and purposes as the Depositor might or could do in person, hereby
ratifying and confirming all that said attorney-in-fact and agent or his
respective substitute or substitutes, shall do or cause to be done by virtue
hereof.

      7. This Trust Agreement may be executed in one or more counterparts.

      8. The number of trustees initially shall be two (2) and thereafter the
number of trustees shall be such number as shall be fixed from time to time by a
written instrument signed by the Depositor, who may increase or decrease the
number of trustees; provided, however, that, to the extent required by the
Business Trust Act, one trustee shall either be a natural person who is a
resident of Delaware or, if not a natural person, an entity which has its
principal place of business in the State of Delaware and otherwise meets the
requirements of applicable Delaware law. Subject to the foregoing, the Depositor
is entitled to appoint or remove without cause any trustee at any time. Any
trustee may resign upon thirty (30) days' prior written notice to the Depositor.

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      9. [Name of Delaware trustee], in its capacity as trustee of the Trust,
shall not have any of the powers or duties of the Trustees as set forth herein
and shall be a trustee of the Trust for the sole purpose of satisfying the
requirements of Section 3807(a) of the Business Trust Act.

      10. This Trust Agreement shall be governed by, and construed in accordance
with, the laws of the State of Delaware (without regard to conflict of laws
principles).

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

                                            AMEREN CORPORATION
                                            as Depositor

                                            By:
                                               ---------------------------------

                                            [NAME OF DELAWARE TRUSTEE],
                                            as Delaware trustee, and not in its
                                            individual capacity

                                            By:
                                               ---------------------------------

                                               ---------------------------------

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