Kinetics and mechanism of oxo-transfer from pyridine N-oxide to dimethyl sulfide catalysed by [RuIII(edta)(H2O)]- complex (edta = ethylenediaminetetraacetate)

The kinetics of the oxidation of [Ru-III(edta)(H2O)](-) (edta = ethylenediaminetetraacetate) (complex-1) with pyridine N-oxide (PyO) to [Ru-V(edta)O](-) (complex-2) and subsequent ore-transfer from complex-2 to dimethylsulfide (dms) leading to the formation of dimethylsulfoxide (dmso) have been studied spectrophotometrically. The rate of formation of ore-complex (2) in the reaction of complex-1 with PyO was found to be substitution controlled and first order both in complex-1 and PyO concentrations. The rate of oxo transfer from complex-2 to dms was found to be first order with respect to [complex-2] and [dms]. Kinetic data and activation parameters are found to be consistent to the proposed mechanism. (C) 1999 Elsevier Science B.V. All rights reserved.