OXIDIZED PHENYL-SUBSTITUTED SESQUIBICYCLIC HYDRAZINES

The effect of alpha- and beta-phenyl substituents on the neutral, +1, and +2 oxidation states of bis-N,N'-bicyclic hydrazines 1 and 2 is discussed. An alpha-phenyl substituent on 2 makes first electron removal 1.8 kcal/mol more difficult, but second electron removal 3.2 kcal/mol less difficult. There is no evidence for significant spin or charge delocalization into the phenyl groups of the +1 oxidation states of these compounds. Exo and endo beta-phenyl-substituted hydrazines xPh-1 and nPh-1 have electron transfer rate constants between their neutral and radical cation forms which are 85% and 55% as large as that for unsubstituted 1, which is argued to demonstrate that attaining relative orientations which allow overlap of the dinitrogen pi systems at the transition state cannot be important; electron transfer proceeds through the alkyl groups. The dications XPh-2(2+) and nPh-2(2+) decompose in acetonitrile much faster than 2(2+) (room temperature lifetimes < 1 s for the phenylated compounds and > 10(4) min for the parent).