Electron spin resonance spectra of amino- and triazolo-semiquinones

Abstract

E.s.r. spectra of hitherto unobserved amino- and triazolo-semiquinones have been obtained by auto-oxidation of the products of the reaction between p-benzoquinone and hydrogen azide. The calculated spin distributions, using the McLachlan S.C.F. methods of aminophenoxyls, amino-semiquinones and triazolosemiquinone radicals, agree well with the experimental values. The observed amino proton splittings fall into two categories; those of the radicals from aminobenzene radical cations and from aminophenoxyls are given by the relationship a[graphic omitted] =ρ_N×–3.0 mT, while those of the aminosemiquinones are given by a[graphic omitted] =ρ_N×–1.0 mT. An analogous relationship (a[graphic omitted] =ρ₀×–1.0 mT) accounts for some hydroxyl proton splittings.