Electronic structure of [M(η-P3C2But2)(CO)3] (M = Mn or Re): a study by photoelectron spectroscopy and density functional calculations

Abstract

The compounds [M(η⁵-P₃C₂Bu^t₂)(CO)₃] (M = Mn 1 or Re 2) are reported and their He I and He II photoelectron spectra assigned. Their electronic structure has been investigated by means of density functional calculations and reasonable agreement between experimental and calculated ionisation energies is achieved. The bonding between the metal and the ring is predominantly donation from the ring to the metal. Back donation into the highest π orbitals of the ring is minimal. The calculations suggest substantial mixing between the ring σ and π orbitals on coordination to the metal. Calculations on [Mn(η⁵-P₃C₂Bu^t₂)₂] reproduce the unusual ²A ground state and show that this results from stabilisation of the metal e₂ type orbitals by formation of a δ bond with the unoccupied π orbitals of the rings.