Photoelectron spectra and bonding in phosphorus compounds
Abstract
Photoelectron spectroscopy and the geometry of the phosphine and phosphorous trifluoride molecular ions
The lowest energy ionization process in phosphine and phosphorous trifluoride produces a vibrational progression. The detailed structure of the photoelectron spectrum suggests that the ground ionic state of phosphorous trifluoride is very probably strictly planar, while that of phosphine is pyramidal with a very small barrier to inversion. The bonding character of electrons in the 2e molecular orbital of phosphine is discussed in terms of the second band in the photoelectron spectrum, its vibrational fine structure and the Jahn-Teller splitting. A HeII photoelectron spectrum of phosphorous trifluoride reveals a further ionization potential and gives a significantly different intensity distribution.
Ab initio calculations of transition metal complexes
The He(I) photoelectron spectra of the isoelectronic series Fe(CO)2(NO)2, Co(CO)3NO and Ni(CO)4 are reported and interpreted by means of ab initio SCF-MO calculations. For the nitrosyl complexes it is found that ionization potentials calculated assuming Koopmans' theorem are seriously in error due to the considerably greater orbital relaxation accompanying ionization from metal than from NO valence orbitals. When such allowance is made for orbital relaxation by performing restricted Hartree-Fock (RHF) calculations on the ionic states, the experimental spectra are accurately reproduced and the observed similarity of the spectra of all three molecules is explained.