Abstract
The kinetics of oxidation of cis-[Cr-III(gly)(2)(H2O)(2)](+) (gly = glycinate) by has been studied in aqueous solutions. The reaction is first order in the chromium(III) complex concentration. The pseudo-first-order rate constant, k (obs), showed a small change with increasing . The pseudo-first-order rate constant, k (obs), increased with increasing pH, indicating that the hydroxo form of the chromium(III) complex is the reactive species. The reaction has been found to obey the following rate law: . Values of the intramolecular electron transfer constant, k (et), the first deprotonation constant of cis-[Cr-III(gly)(2)(H2O)(2)](+), K (3) and the equilibrium formation constant between cis-[Cr-III(gly)(2)(H2O)(OH)] and , K (4), have been determined. An inner-sphere mechanism has been proposed for the oxidation process. The thermodynamic activation parameters of the processes involved are reported.