Unstable intermediates. Part CXLIX. An electron spin resonance study of various phosphinyl radicals formed by solid-state radiolysis

Abstract

One of the major products when a range of trivalent phosphorus compounds was exposed to ⁶⁰Co γ-rays at 77 K was shown by e.s.r. spectroscopy to be the corresponding phosphinyl radical, ṖR₂. These radicals, which include ṖH₂, Ṗ(Me₂CH)₂, Ṗ(OMe)₂, Ṗ(SMe)₂, ṖPh₂, ṖPh(Cl), and ṖCl₂, are all characterised by a ³¹P parallel hyperfine coupling constant in the 240–290 G range and a perpendicular coupling close to zero. The conditions under which these radicals are formed, and the mechanisms involved, are outlined and discussed.