CONFORMATIONALLY PROTECTED HYDRAZINE RADICAL CATIONS AND THE GEARING EFFECT ON A HYDRAZINE ELECTRON-TRANSFER REACTION

The N-isopropylated hydrazine radical cations from 7 (22/tBu,iPr) and 9 (22/iPr2) are isolable and are the first examples of isolable hydrazine radical cations which lack all C(alpha)-H bonds being protected as bridgehead carbons in bicyclic rings. The cyclic voltammogram of 9 shows electrochemically irreversible oxidation and reduction waves at platinum. It is argued that this results from a gearing effect of the isopropyl groups, which causes the radical cation from neutral 9 to be generated in an unstable conformation. Kinetic and thermodynamic conformational effects which cause hydrazine cyclic voltammetry curves to be electrochemically irreversible are contrasted.