The electronic structure of transition metal complexes containing organic ligands

Abstract
The He(I), He(II) and X-ray photoelectron spectra of iron tricarbonyl butadiene are reported and these measurements, together with the bonding in the complex, are discussed with the aid of ab initio SCF MO calculations. The latter yield a substantial negative charge on the butadiene ligand, and the low energy photoelectron spectra can only be satisfactorily interpreted when deviations from Koopmans' theorem are taken into account by performing RHF calculations on the various low-lying ionic states of the molecule.