The powers of council shall be legislative only. It shall perform no administrative duties nor appoint nor confirm any officer or employee in the city government except those of its own body, except as otherwise provided by law. All contracts requiring the authority of council for their execution shall be entered into and conducted to performance by the board or officers having charge of the matters to which they relate, and after authority to make the contracts has been given, and the necessary appropriation made, council shall take no further action thereon.
(R.C. § 731.05)