Redox reactions of a RuIII-edta complex with thioamino acids. Kinetic and mechanistic studiesElectronic supplementary information (ESI) available: kinetic traces at different pH and alkali metal concentration, plots of kobsversus[M+], Eyring plots and plots of lnkobsversuspressure. See DOI: 10.1039/c0dt01444c

The kinetics of reduction of [RuIII(edta)pz]−(edta4−= ethylenediaminetetraacetate; pz = pyrazine) by thioamino acids (RSH = cysteine, glutathione) resulting in the formation of a red [RuII(edta)pz]2−species (λmax= 462 nm) has been studied spectrophotometrically using both conventional mixing and stopped-flow techniques. The time course of the reaction was followed as a function of [RSH], pH, temperature and pressure. Alkali metal ions were found to have a positive influence (K+> Na+> Li+) on the reaction rate. Kinetic data and activation parameters are interpreted in terms of a mechanism involving outer-sphere electron transfer between the reaction partners. A detailed reaction mechanism in agreement with the spectral and kinetic data is presented. [ABSTRACT FROM AUTHOR]