Abstract: | The kinetics of oxidation of CrIII(Dpc)(Asp)(H2O)2] (Dpc = dipicolinic acid and Asp = DL ‐aspartic acid) by N‐bromosuccinimide (NBS) in aqueous solution have been found to obey the equation: where k2 is the rate constant for the electron transfer process, K1 is the equilibrium constant for deprotonation of CrIII(Dpc)(Asp)(H2O)2], K2 and K3 are the pre‐equilibrium formation constants of precursor complexes CrIII(Dpc)(Asp)(H2O)(NBS)] and CrIII(Dpc)(Asp)(H2O)(OH)(NBS)]?. Values of k2 = 4.85 × 10?2 s?1, K1 = 1.85 × 10?7 mol dm?3, and K2 = 78.2 mol?1 dm3 have been obtained at 30°C and I = 0.1 mol dm?3. The experimental rate law is consistent with a mechanism in which the deprotonated CrIII(Dpc)(Asp)(H2O)(OH)]? is considered to be the most reactive species compared to its conjugate acid. It is assumed that electron transfer takes place via an inner‐sphere mechanism. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 394–400, 2004 |