Electron spin resonance studies of oxidation. Part V. Reactions of lead tetra-acetate. (IV.) Iminoxy-radicals derived from oximes

Abstract

Ketoximes have been oxidised by lead tetra-acetate to give (comparatively stable) iminoxy-radicals whose electron spin resonance spectra have been studied. The radicals are of σ-type and the modes of interaction between the unpaired electron and the protons in the radical are markedly different from those in π-radicals. In particular, long-range couplings are observed which are strongly dependent on the stereochemistry of the bonds joining the proton concerned to the iminoxy-function. By studying the radicals from alicyclic oximes of known stereochemistry, it has been possible to make a number of deductions about the variation in the coupling with the geometry of the system, although the mechanism of transmission of spin-density, and the underlying reasons for the stereochemical dependence of the couplings, are not yet clear.