DYNAMICS OF THE COORDINATION EQUILIBRIA IN SOLUTIONS CONTAINING COPPER(II), COPPER(I), AND 2,9-DIMETHYL-1,10-PHENANTHROLINE AND THEIR EFFECT ON THE REDUCTION OF O-2 BY CU(I)
Yb. Lei et Fc. Anson, DYNAMICS OF THE COORDINATION EQUILIBRIA IN SOLUTIONS CONTAINING COPPER(II), COPPER(I), AND 2,9-DIMETHYL-1,10-PHENANTHROLINE AND THEIR EFFECT ON THE REDUCTION OF O-2 BY CU(I), Inorganic chemistry, 34(5), 1995, pp. 1083-1089
The rates of establishment of coordination equilibria in solutions con
taining 2,9-dimethyl-1,10-phenanthroline (DMP) and Cu(II) when the lat
ter is reduced to Cu(I) at electrodes were measured by means of cyclic
voltammetry. Formal potentials for the Cu(DMP)(2+/+) and CU(DMP)(2)(2
+/+) couples were evaluated (0.08 and 0.35 V vs SCE, respectively) fro
m which the equilibrium constants for the formation of the Cu(DMP)(+)
and Cu(DMP)(2)(+) complexes were calculated (6.7 x 10(8) M(-1) and 1.5
x 10(10) M(-2), respectively). Cu(DMP)(2)(+) is not oxidized by O-2,
but Cu(DMP)(+), generated by addition of Cu2+ to solutions of Cu(DMP)(
2)(+), is oxidized by O-2. A rate law is presented that accounts for t
he observed second-order dependences of the reaction rate on [Cu2+], [
Cu(DMP)(2+)], and [Cu(DMP)(2)(+)](-1). The stoichiometric reduction of
O-2 by Cu(DMP)(+) in solution is contrasted with the catalytic reduct
ion of O-2 by the same complex adsorbed on graphite electrodes.