The reactions of radical anions. Part VIII. Effect of solvent on the electron spin resonance spectrum of the radical anion of 4,7-phenanthroline-5,6-quinone (Entobex)

Abstract

The radical anion of 4,7-phenanthroline-5,6-quinone (I)(Entobex) has been prepared electrolytically in dimethyl sulphoxide, and in mixtures of dimethyl sulphoxide with dioxan, methyl cyanide, and ethyl alcohol. The change in the hyperfine coupling constants of N(ca. 6%) and of H(2,9)(ca. 2·5%) as the solvating ability of the solvent increases is consistent with an increase in electronegativity at the oxygen atoms. λ_max. for the radical anion in dimethyl sulphoxide is 575 mµ.