Electron spin resonance of complexes of pentacyanocobaltate(II) with aromatic nitro and nitroso compounds

Abstract

AbstractBy means of ESR techniques a systematic study has been made of radicals prepared by reaction of aromatic nitro and nitroso compounds with pentacyanocobaltate(II). Assignments of hyperfine coupling constants have been confirmed by deuterium substitution. The structure of the radicals, aryl pentacyanocobalt nitroxides, has been confirmed by experiments with nitro, corresponding nitroso and dinitro compounds and experiments with varying cobalt‐substrate ratio. Substituent effects on the nitrogen hyperfine interactions have been expressed in terms of a Hammett relationship aN = −1.46 σ ± 13.79. A qualitative ligand‐field model is given to get a better understanding of the delocalization of the unpaired electron over the transition metal ion and the aromatic ligand.