Electron spin resonance spectrum of a radical cation of ethyl bromide radiolytically produced in trichlorofluoromethane at 4 K: a re-investigation

Abstract

Exposure of a dilute solution of ethyl bromide in CFCl₃ to X-rays at 4 K gave a species exhibiting a large hyperfine coupling to bromine, with smaller splittings from one chlorine nucleus and two protons. Computer simulations of this well resolved spectrum showed that the g tensor is rhombic with the principal elements typical of π³ radicals. The species is now unequivocally identified as the cation of ethyl bromide having a weak σ* bond to a single chlorine atom of a neighbouring solvent molecule. The g tensor is used to show the relationship between EtBr^+˙ and the isostructural π³ radicals RO˙, RS˙, and CH₃I^+˙