title: Ru(EDTA) mediated partial reduction of O2 by H2S.
abstract: An effective procedure for selective reduction of O2 to H2O2 exploring the use of hydrogen sulfide, an obnoxious industrial pollutant as reductant is reported herein. The reduction of [Ru(III)(EDTA)pz](-) (EDTA(4-) = ethylenediaminetetraacetate; pz = pyrazine) by hydrogen sulfide resulting in the formation of a red [Ru(II)(EDTA)pz](2-) complex (λmax = 462 nm) has been studied spectrophotometrically and kinetically using both rapid scan and stopped-flow techniques. The time course of the reaction was followed as a function of [HS(-)]i, pH (5.5-8.5), and temperature. 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 (admittedly speculative) involving outer-sphere electron transfer between the reaction partners. Reaction of the red [Ru(II)(EDTA)pz](2-) complex with molecular oxygen regenerates the [Ru(III)(EDTA)pz](-) species in the reacting system along with the formation of H2O2, a partially reduced product of dioxygen (O2) reduction. A detailed reaction mechanism in agreement with the spectral and kinetic data is presented.
authors: Chemistry and Biomimetics Group, CSIR-Central Mechanical Engineering Research Institute, MG Avenue, Durgapur-713209, India. dchat57@hotmail.com.
authors: Debabrata
authors: D
authors: Chatterjee
authors: Namita
authors: N
authors: Jaiswal
authors: Papiya
authors: P
authors: Sarkar
mesh_terms: D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry*; D006862:Hydrogen Sulfide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013696:Temperature
chemical_list: D056831:Coordination Complexes; D012428:Ruthenium; D004492:Edetic Acid; D010100:Oxygen; D006862:Hydrogen Sulfide