THE ELECTRON SPIN RESONANCE SPECTRA OF DINITRONAPHTHALENE ANION RADICALS

The radical anions of 1,4-dinitronaphthalene, 1,5-dinitronaphthalene, and 1,8-dinitronaphthalene have been generated by electrolytic means, and their e.s.r. spectra recorded. The spectra consist of 61, 111, and 85 lines respectively, and can be analyzed in terms of one nitrogen and three proton coupling constants, consistent with the full symmetry of the species giving rise to them. These constants are, for 1,4-dinitronaphthalene: aN = 0.97 G, aH2 = 1.69 G, aH5 = 0.53 G, and aH6 = 0.41 G; for 1,5-dinitronaphthalene: aN = 2.30 G, aH2 = 2.42 G, aH3 = 0.44 G, and aH4 = 2.82 G; for 1,8-dinitronaphthalene: aN = 3.03 G, aH2 = 3.63 G, aH3 = 0.95 G, and aH4 = 3.73 G. Whereas the nitrogen coupling constants can be unambiguously assigned, this, in the absence of deuteration studies say, is not the case for the three sets of equivalent protons. As an aid in the assignment of proton coupling constants, Hückel LCAO calculations and simplified SCFMO calculations by the method of McLachlan have been performed. The first mentioned of the above proton constants could thus be assigned with reasonable certainty, the remaining two aHi remain ambiguous.