EFFECT OF FUMARATE ON THE KINETICS AND REACTION-MECHANISM OF CU-AQ(+)WITH DIOXYGEN

The kinetics of the reactions: Cu-aq(+) + O-2 reversible arrow (CuO2)( aq)(+) and (CuO2)(+) + Cu-aq(+) -->(H) 2Cu(aq)(2+) + H2O2 were studied applying the pulse radiolysis technique, Kk = (2.3 +/- 0.4) x 10(8) d m(6) s(-1) mol(-2), in good agreement with the value calculated from l iterature data. The complex Cu-I(fum) (fum = fumarate) reacts consider ably slower than Cu-aq(+) with dioxygen so that the rate law reflects only the reaction of Cu-aq(+). A comparison of the results with those reported for the ligands L (water, CH3CN, phenanthroline, bipyridine o r fumarate) indicates that the ligand affects the stability constant o f the (CuL)-L-I . O-2 complex, and for fumarate also the subsequent re action.