Kinetics and mechanism of the oxidation of hydroquinones by a trans-dioxoruthenium(VI) complex

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • William W. Y. Lam
  • Mendy F. W. Lee
  • Tai-Chu Lau

Detail(s)

Original languageEnglish
Pages (from-to)315-321
Journal / PublicationInorganic Chemistry
Volume45
Issue number1
Publication statusPublished - 9 Jan 2006

Abstract

The kinetics of the oxidation of hydroquinone (H2Q) and its derivatives (H2Q-X) by trans-[RuVI(tmc)(O) 2]2+ (tmc = 1,4,8,11-tetramethyl-1,4,8,11- tetraazacyclotetradecane) have been studied in aqueous acidic solutions and in acetonitrile. In H2O, the oxidation of H2Q has the following stoichiometry: trans-[RuVI(tmc)(O)2] 2+ + H2Q → trans-[RuIV(tmc)(O)(OH 2)]2+ + Q. The reaction is first order in both Ru VI and H2Q, and parallel pathways involving the oxidation of H2Q and HQ- are involved. The kinetic isotope effects are k(H2O)/k(D2O) = 4.9 and 1.2 at pH = 1.79 and 4.60, respectively. In CH3CN, the reaction occurs in two steps, the reduction of trans-[RuVI(tmc)(O)2]2+ by 1 equiv of H2Q to trans-[RuIV(tmc)(O)(CH3CN)] 2+, followed by further reduction by another 1 equiv of H 2Q to trans-[RuII(tmc)(CH3CN)2] 2+. Linear correlations between log(rate constant) at 298.0 K and the O-H bond dissociation energy of H2Q-X were obtained for reactions in both H2O and CH3CN, consistent with a H-atom transfer (HAT) mechanism. Plots of log(rate constant) against log(equilibrium constant) were also linear for these HAT reactions. © 2006 American Chemical Society.

Citation Format(s)

Kinetics and mechanism of the oxidation of hydroquinones by a trans-dioxoruthenium(VI) complex. / Lam, William W. Y.; Lee, Mendy F. W.; Lau, Tai-Chu.

In: Inorganic Chemistry, Vol. 45, No. 1, 09.01.2006, p. 315-321.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review