The electron spin resonance spectra of some aromatic nitrile anions

The E.S.R. spectra of the anions of benzonitrile, phthalonitrile, terephthalonitrile and p-tolunitrile are described. The ring proton hyperfine splitting constants indicate that in each case, the molecular orbital of the unpaired electron can be closely correlated with one of the two degenerate antibonding orbitals of benzene itself.