HOMOLYTIC AND HETEROLYTIC N-H BOND STRENGTHS

E1/2 values for the reversible cyclic voltammetric (CV) oxidations of the nitranions derived from iminostilbene, phenoxazine, and phenothiazine, obtained at 1000 V/s scan rates, are in remarkable agreement with irreversible CV anodic peak potentials obtained at 0.1 V/s scan rates and therefore suggest that homolytic N-H bond dissociation energies based on the irreversible data do not suffer from large errors associated with electrochemical irreversibilities. Acidity and 10 000 V/s redox data for iminostilbene and its respective anion and radical, when compared to similar data for 9-phenylxanthene and its respective anion and radical, suggest that the N-H bond in iminostilbene is about 22 kcal/mol stronger, in a heterolytic cation/hydride forming sense, than the 9C-H bond in 9-phenylxanthene.