Photoelectron spectra of halides. Part III. Trifluorides and oxide trifluorides of nitrogen and phosphorus, and phosphorus oxide trichloride

Abstract

High-resolution photoelectron spectra, obtained with He^I(584 Å) and He^II(304 Å) resonance radiation, are reported for NF₃, PF₃, NOF₃, and POF₃. A low-resolution He^I spectrum of POCl₃ is also reported; vertical ionisation potentials (i.p.) and in many cases estimates of adiabatic i.p. also, are tabulated for all the compounds. The agreement of the experimental orbital assignments with ab initio calculations is excellent for PF₃, POF₃, PCl₃, POCl₃, good for NF₃, but less good for NOF₃. The correlations of the energy levels of PF₃ with those of POF₃, and of PCl₃ with POCl₃, follow a simple pattern of strong stabilisation of the lone pair of the donor molecule upon bonding to the O atom, with smaller stabilisations of the remaining orbitals. Correlations of the levels of POCl₃ with those of SiCl₄, and of POF₃ with SiF₄ are similarly satisfactory, but no simple pattern appears in the correlation of NOF₃ with CF₄ or with NF₃.