Electron addition to triphenylmethyl arsonium iodide. An electron spin resonance study

Abstract

Exposure of crystalline Ph₃AsMe⁺I^– crystals to ⁶⁰Co γ-rays at 77 K yields an electron-adduct having e.s.r. parameters characteristic of methyl radicals weakly interacting with a Ph₃As molecule. We now find that, on annealing, this species dissociates to give normal methyl radicals, whilst solutions in methanol (CD₃OD) give, on electron addition at 77 K, the normal arsoranyl radical [Ph₃ÅsMe] together with methyl radicals, there being no trace of the adduct formed in the crystalline material. Reasons for these differences are discussed and it is suggested that the arsoranyl radical rearranges to a σ^* species as a necessary step in the dissociation process.