Electronic structure of organometallic compounds. Part 28. Photoelectron spectra of transition-metal-1-methylborinato complexes in the outer valence region. Semiempirical model calculations based on Green's function formalism

The electronic structures of the 1-methylborinato complexes of V(CO)/sub 4/ (1), Mn(CO)/sub 3/ (2), Co(CO)/sub 2/ (3), and Co(C/sub 4/H/sub 4/) (4) have been studied by means of INDO calculations and their He I photoelectron (PE) spectra. The calculated rotational barriers and the orbital sequences of 1-3 have been compared with their isovalent (C/sub 5/H/sub 5/)M(CO)/sub n/ species. The measured ionization energies are discussed on the basis of those calculated by means of the Green's function formalism. It if found that Koopmans' theorem is only valid in the case of 1. Significant differences between the filling scheme of the canonical MO's in the ground state and the sequence of the ionic states are demonstrated for 2-4. It is shown that large relaxation energies are partially compensated by pair-relaxation contributions (i.e., many-body correction). 63 references, 10 figures, 5 tables.