Upon preliminary approval by the State Bond Commission pursuant to the provisions of section 3-20, the state, acting by and through the Commissioner of Housing, may enter into a contract with a developer, the authority or a mortgagor of the authority for state financial assistance in the form of a loan secured by a second mortgage for any housing project for which the authority has provided financial assistance in the form of a loan secured by a first mortgage. Such loan shall be made for the purpose of providing additional financing for the project. Any loan made under this section shall bear interest payable quarterly on the first days of January, April, July and October for the preceding calendar quarter, or at such other times as are determined by the commissioner or the authority, as the case may be, at a rate determined by the State Bond Commission under subsection (t) of section 3-20 and shall be repayable in such installments as may be determined by the commissioner or the authority, as the case may be, within fifty years from the date of completion of the project. Loan repayments shall be paid to the State Treasurer and deposited in the General Fund.