Radiation mechanisms. Part II. Electron spin resonance studies of the mechanism of radiation processes in trivalent phosphorus derivatives

Abstract

A range of phosphites (trimethyl phosphite, trimethyl and tripropyl thiophosphite, di-isopropylphosphinyl chloride, diphenylphosphinyl chloride, and dithioethylphosphinyl chloride) have been exposed, either pure or in a range of solvents, to ⁶⁰Co γ-rays at 77 K. The radical products have been analysed by e.s.r. spectroscopy. We conclude that, after electron addition, the radical anions may protonate on phosphorus, lose an anionic ligand to give a phosphinyl radical or lose a neutral ligand (alkyl, alkoxy, thiyl or chlorine radicals). These radicals may subsequently add to adjacent molecules to give a range of phosphoranyl species. It is also suggested that the primary anion may sometimes rearrange to give an alkylphosphoranyl radical directly.

The primary cation-radicals, ·PL₃⁺, react efficiently with PL₃ neighbours to give the dimer-cations, P₂L₆⁺, but in dilute solution this is suppressed. Addition of methyl bromide suppresses anion formation and the resulting less complicated e.s.r. spectra show one of the M_I= 0 components (1,0) for the dimer-cations.