Kinetics and mechanisms of oxidation of triphenylphosphine with iodosylbenzene catalyzed by N-hydroxyethylethylenediaminetriacetatoruthenate(III) in water-dioxane medium

Abstract

The kinetics of oxygenation of [Ru^III(HEDTA)(H₂O)] complex 1, where HEDTA = N-hydroxyethylethylenediaminetriacetate anion, with iodosylbenzene was studied spectrophotometrically by the stopped flow technique. The rate of formation of [Ru^V(HEDTA)(O)] complex 2 was monitored at the characteristic peak of the oxo complex 2 at 393 nm. Subsequent oxygen atom transfer from complex 2 to PPh₃ was investigated by following the disappearance of the oxo peak at 393 nm. The rate and activation parameters (ΔH≠ and ΔS≠) for both oxygenation of complex 1 with PhIO and oxygen atom transfer from complex 2 to PPh₃ were determined and the experimental results are discussed with reference to the data reported for the oxidation of PPh₃ catalyzed by the corresponding EDTA-H and PDTA-H complexes.