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 reacti ons of these molecules with hydrazines, ferrocenes, and tetramethyl-p- phenylenediamine (TMPD) using Marcus theory. Cross-reaction rate const ants for eight reactions are reported. Included are six cross-reaction s 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 hydra zine-hydrazine and hydrazine-TMPD(+) ET reactions. The crossreaction r ate constants are used to test the application of Marcus theory to hyd razine ET reactions and to extract estimates of hydrazine self-exchang e ET rate constants in systems for which direct measurement is present ly impossible.