Unstable intermediates. Part LXVII. Electron spin resonance spectrum of cyclohexadienyl radicals from resorcinol: the mechanism of radiation damage

Abstract

At 77°K, exposure of resorcinol to γ-rays gave, primarily, close pairs of phenoxy-radicals. On warming to room temperature these radicals were lost, and there was no evidence for the formation of cyclohexadienyl radicals. Exposure to hydrogen atoms at 77°K or room temperature gave low yields of a species having only a broad single-line e.s.r. spectrum. In marked contrast, γ-rays at room temperature gave cyclohexadienyl radicals in good yield. Use of deuteriated material established that the hydrogen atom was initially bonded to carbon rather than oxygen. Hyperfine coupling tensors obtained from single-crystal studies are reported, and a possible explanation of these unusual differences is suggested.