Intermolecular electron-transfer reactions involving hydrazines

The self-exchange electron-transfer (ET) rate constant k(22) for 1,2,3,4,5-pentamethylferrocene was determined by NMR line broadening to be 8.5(+/-0.8) x 10(6) M(-1) s(-1) (25 degrees C, CD3CN/0.09 M Et(4)NBF(4)) and k(11) for the bis-N,N-bicyclic hydrazine, 9,9'-bi-9-azabicyclo[3.3.1]nonane, to be 8.7(0.5) x 10(3) M(-1) s(-1) (25 degrees C, CH2Cl2). These self-exchange rate constants are used to analyze cross reactions of these molecules with hydrazines, ferrocenes, and tetramethyl-p-phenylenediamine (TMPD) using Marcus theory. Cross-reaction rate constants for eight reactions are reported. Included are six cross-reactions between methylferrocenes and four cyclic hydrazines, one hydrazine, hydrazine-reaction, and the reduction of TMPD(+) by a cyclic hydrazine. These are the first cross-reaction rate constants reported for hydrazine-hydrazine and hydrazine-TMPD(+) ET reactions. The crossreaction rate constants are used to test the application of Marcus theory to hydrazine ET reactions and to extract estimates of hydrazine self-exchange ET rate constants in systems for which direct measurement is presently impossible.