ELECTRON-TRANSFER REACTIONS OF OPTICALLY-ACTIVE [CO(PHEN)3]3+/2+ AND DERIVATIVES

The kinetics of the self-exchange reactions of [Co(phen)3]3+/2+, [Co(4,7-Me2phen)3]3+/2+, and [Co(5,6-Me2phen)3]3+/2+(phen = 1,10-phenanthroline) have been examined at 25.0 °C and 0.10 M ionic strength by observing the racemization of the optically enriched oxidized form in the presence of the racemic reduced form. Reaction rates are found to be dependent on the nature of the counterion, and the formation of ion multiplets is proposed. Activation parameters have been determined for the [Co-(phen)3]3+/2+reaction. The kinetics of the oxidation of the complexes [Co(4,7-Me2phen)3]2+ and [Co(5,6-Me2phen)3]2+by [Co(phen)3]3+ have also been investigated. They are outer-sphere processes with a simple first-order dependence on both reactants. The oxidation of [Co(4,7-Me2phen)3]2+ by [Co(phen)3]3+is shown to be stereoselective with a 15% ΔΛ stereochemical preference. © 1990, American Chemical Society. All rights reserved.