Semi-empirical MNDO SCF-MO study of radicals derived from γ-radiolysis of tertiary phosphines and trialkylphosphites
Abstract
Calculations have been made, using the MNDO-UHF approximation, of the molecular and electronic structures of a range of phosphorus- and carbon-centred radicals formed in the γ-radiolysis of tertiary phosphines and of trialkylphosphites. The radical cations R3P+ are all calculated to have C3v, symmetry (for R = Me, Et, Prn, Bun): as the length of the alkyl chain increases, the phosphorus approaches more closely to planarity. In the radical cations (RO)3P+(R = H, Me, Et), the geometry at phosphorus is close to tetrahedral: two conformers, of C3 and Cs symmetry, were found for (MeO)3P+. Dinuclear cation radicals(R3P)2+ and [(RO)3P]2+ were found to be σ* radicals, having the SOMO strongly confined in the P–P bonds. (H3P)2+ and (Me3P)2+ are calculated to have D3d symmetry: for (Et3P)2+, [(HO)3P]2+, and [(MeO)3P]2+ two diastereoisomeric conformers, having D3 and S6 symmetry, were found.