E.s.r. investigation of alkoxynitroxide free radicals from the photolysis of nitrobenzenes and of heterocyclic nitro compounds

Abstract

Electron-donating effects of substituents have been found to affect critically the formation of alkoxynitroxide radicals by u.-v. photolysis of aromatic and heterocyclic nitro compounds. This has been explained in terms of the relative hydrogen-abstracting abilities of (n,π*) and (π,π*) triplet states. The magnitudes of nitrogen coupling constants appear to be dependent upon inductive and resonance effects and, in some cases, upon steric hindrance from ortho substituents. Energetics of the decay reactions of some arylalkoxynitroxide radicals are reported.