Kinetics and mechanism of the reaction of [RuIII(edta)(H2O)]− with HOBr to form an intermediate RuVO complex in aqueous solution

Abstract

The interaction of [Ru^III(edta)(H₂O)]⁻ (1) (edta = ethylenediaminetetraacetate) with the oxygen transfer agent HOBr, was studied kinetically as a function of [HOBr] and temperature (5–35 °C) at a fixed pH of 6.2. Spectroscopic evidence is reported for the formation of a high valent intermediate (edta)Ru^VO complex. Water soluble 2,2′-azobis(3-ethylbenzithiazoline-6-sulfonate) (ABTS) was employed as a trap for this intermediate in order to gain further mechanistic information. Reactions were carried out under pseudo-first conditions for [ABTS] ≫ [HOBr] ≫ [1], and were monitored as a function of time for the formation of the one-electron oxidation product ABTS˙⁺. The reported kinetic data are interpreted in terms of a suggested reaction mechanism and discussed in reference to data reported before.