An electron spin resonance study of the asymmetric solvation of the m-dinitrobenzene and 3,5-dinitrobenzoate radical anions

Abstract

The e.s.r. spectra obtained by reduction of m-dinitrobenzene and 3,5-dinitrobenzoic acid with aqueous alkaline sodium dithionite have been re-investigated. In addition to the dominant interaction with one nitrogen nucleus which has been previously reported, a further splitting of 0·24 gauss due to the other nitrogen nucleus has been resolved in both spectra. The spectra exhibit line-width effects characteristic of the slow interconversion of two asymmetric conformers of the nitro-radical anion in which the environments of the nitro-groups are exchanged. A mean life-time of 1·1 × 10^–6 sec. has been estimated for the conformers of the 3,5-dinitrobenzoate anion radical. The asymmetry of these conformers is attributed to strong interaction between the solvent and one nitro-group.