Inner-Sphere Oxidation of Binary and Ternary Uridine Chromium(III) Complexes Involving Aspartate by Periodate

The oxidation of the binary complex chromium(III)-uridine, [CrIII (Urd)(H2O)5]3+ and the ternary one chromium(III) uridine aspartic complex, [CrIII (Urd)(Asp) (H2O)3]2+, by periodate have been studied kinetically in aqueous solution to yield CrVI , over 20–40◦C and the 2.62–3.68 pH range. The oxidation of [CrIII (Urd)(H2O)5]3+ by periodate, obeys the rate law, rate = [CrIII urd(H2O)5]3+ [H5IO6]{k4K5 + (k5K6K2/[H+)}, while the reaction of [CrIII (Urd)(Asp)(H2O)3]2+ with periodate following the rate equation d[CrVI ]/dt = (k6K8[CrIII ]T [IO4 ])/ {1 + K8[IO4 ] + ([H+]/K7)}. Thermodynamic activation parameters have been calculated.