Studies on nitroaromatic compounds. Part II. An electron spin resonance study of the radical anions of some nitronaphthalic anhydrides

Abstract

The radical anions of 2,5-dinitronaphthalic anhydride, 4,5-dinitronaphthalic anhydride, 2,4,5-trinitronaphthalic anhydride, and 2,4,5,7-tetranitronaphthalic anhydride have been prepared by reduction with sodium and their e.s.r. spectra have been recorded. Analysis of the spectra has yielded proton and nitrogen hyperfine coupling constants which are assigned, where possible, on the basis of molecular orbital calculations performed by use of the Hückel–LCAO method and the approximate configuration interaction method of McLachlan. The calculated π-electron spin densities agree well in most cases with experimental values. The radical-anion spectra have been simulated satisfactorily except in the case of the radical anion of 2,4,5-trinitronaphthalic anhydride where linewidth alternation alters the intensities of the lines in the spectrum.