Ionization energies and thermal fragmentation patterns of gaseous cyclopolyarsanes and -phosphanes EnRn(E = As or P; R = Me, But, or CF3; n= 3–5): a joint temperature-variable field ionization mass spectrometric and ultraviolet photoelectron spectroscopic study

Abstract

Ultraviolet photoelectron spectroscopic (u.p.s.) data for gaseous As₄Bu^t₄, As₄(CF₃)₄, and As₅Me₅ are presented and discussed with respect to the known ionization potentials of the parent cyclopolyphosphanes. Pyrolytically induced fragmentation patterns of representative cyclopoly-phosphanes and -arsanes in the gas phase have been analysed by high-temperature field ionization mass spectrometry (f.i.m.s.) and u.p.s. Evidence for a thermally generated transient phosphinidene P(CF₃) from [P(CF₃)]_n(n= 4 or 5) in the gaseous phase is provided by f.i.m.s., whereas products such as P₂ and CF₂ from secondary reactions are revealed by u.p.s. The u.p.s. upon thermal fragmentation of Sb(CF₃)₃ is also presented.