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

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

doi:10.1021/ic051382i

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

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

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

20 Citations (Scopus)

Abstract

The kinetics of the oxidation of hydroquinone (H₂Q) and its derivatives (H₂Q-X) by trans-[Ru^VI(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-[Ru^VI(tmc)(O)₂] ²⁺ + H₂Q → trans-[Ru^IV(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-[Ru^VI(tmc)(O)₂]²⁺ by 1 equiv of H₂Q to trans-[Ru^IV(tmc)(O)(CH₃CN)] ²⁺, followed by further reduction by another 1 equiv of H ₂Q to trans-[Ru^II(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.

Original language	English
Pages (from-to)	315-321
Journal	Inorganic Chemistry
Volume	45
Issue number	1
DOIs	https://doi.org/10.1021/ic051382i
Publication status	Published - 9 Jan 2006

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

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. {\textcopyright} 2006 American Chemical Society.",

author = "Lam, {William W. Y.} and Lee, {Mendy F. W.} and Tai-Chu Lau",

year = "2006",

month = jan,

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doi = "10.1021/ic051382i",

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journal = "Inorganic Chemistry",

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TY - JOUR

T1 - Kinetics and mechanism of the oxidation of hydroquinones by a trans-dioxoruthenium(VI) complex

AU - Lam, William W. Y.

AU - Lee, Mendy F. W.

AU - Lau, Tai-Chu

PY - 2006/1/9

Y1 - 2006/1/9

N2 - 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.

AB - 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.

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U2 - 10.1021/ic051382i

DO - 10.1021/ic051382i

M3 - RGC 21 - Publication in refereed journal

C2 - 16390070

SN - 0020-1669

VL - 45

SP - 315

EP - 321

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 1

ER -

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

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