title: Redox reactions of a Ru(III)-edta complex with thioamino acids. Kinetic and mechanistic studies.
abstract: The kinetics of reduction of [Ru(III)(edta)pz]⁻ (edta⁴⁻ = ethylenediaminetetraacetate; pz = pyrazine) by thioamino acids (RSH = cysteine, glutathione) resulting in the formation of a red [Ru(II)(edta)pz]²⁻ species (λ(max) = 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.
authors.affiliation: Chemistry and Biomimetics Group, Central Mechanical Engineering Research Institute, CSIR, MG Avenue, Durgapur-713209, India. dchat57@hotmail.com
authors.forename: Debabrata
authors.initials: D
authors.lastname: Chatterjee
authors.forename: Ujjwal
authors.initials: U
authors.lastname: Pal
authors.forename: Sarita
authors.initials: S
authors.lastname: Ghosh
authors.forename: Rudi
authors.initials: R
authors.lastname: van Eldik
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry*; D005978:Glutathione / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008672:Metals, Alkali / Q000737:chemistry; D010084:Oxidation-Reduction; D011312:Pressure; D012428:Ruthenium / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D056831:Coordination Complexes; D008672:Metals, Alkali; D012428:Ruthenium; D004492:Edetic Acid; D005978:Glutathione; D003545:Cysteine