ESR study of the anion radical of anthraquinone and the computer analysis of ESR spectra

Abstract

The anion radical of anthraquinone has been studied, using electron spin resonance (esr) spectroscopy. Anion radicals were produced by electrolytic reduction and by reduction with alkali metals. The anion radical produced electrolytically was found to be essentially unassociated with any cation. The proton coupling constants for these spectra varied with the solvent used. In the metal reduction the anion radical and the metal cation were closely associated as ion-pairs. The degree of association was found to vary with temperature, solvent and metal cation. In the Na and K reduction spectra an alternation of line widths was observed. This line width alternation has been attributed to the intramolecular migration of the metal cation between the two oxygen atoms. In order to analyze the experimental spectra it was necessary to include in the theory of hyperfine interaction a mechanism for producing line width alternation, A computer program was written which can be used in the analysis of spectra which exhibit line width alternation.