Electron-transfer reactions in [Ru(edta)(pyz)](-) (edta equals ethylenedinitrilotetraacetate, pyz equals pyrazine)

The kinetics of reduction of [Ru-III(edta)(pyz)](-)(edta = ethylenedinitrilotetraacetate, pyz = pyrazine) with L-ascorbic acid (H(2)A) and catechol (H(2)cat) was studied spectrophotometrically as a function of [H(2)A] or [H(2)cat], pH, ionic strength and temperature (25-45 degrees C). The reduction was found to be first order in both the complex and reductant concentrations. The pH dependence of the process(for H(2)A) was ascribed to the deprotonation of H(2)A. Kinetic data and activation parameters are interpreted in terms of a mechanism involving outer-sphere electron transfer.