Kinetics and Mechanism of the Oxidation of Alkylaromatic Compounds 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
  • Shek-Man Yiu
  • Douglas T. Y. Yiu
  • Tai-Chu Lau
  • Wing-Ping Yip
  • And 1 others
  • Chi-Ming Che

Detail(s)

Original languageEnglish
Pages (from-to)8011-8018
Journal / PublicationInorganic Chemistry
Volume42
Issue number24
Publication statusPublished - 1 Dec 2003

Abstract

The oxidations of a series of 21 alkylaromatic compounds by trans-[Ru VI(L)(O)2]2+ (L = 1,12-dimethyl-3,4:9,10-dibenzo-1,12-diaza-5,8-dioxacyclopentadecane) have been studied in CH3CN. Toluene is oxidized to benzaldehyde and a small amount of benzyl alcohol. 9,10-Dihydroanthracene is oxidized to anthracene and anthraquinone. Other substrates give oxygenated products. The kinetics of the reactions were monitored by UV-vis spectrophotometry, and the rate law is: -d[RVI]/dt = k2[RuVI][ArCH3]. The kinetic isotope effects for the oxidation of toluene/d8-toluene and fluorene/d10-fluorene are 15 and 10.5, respectively. A plot of ΔH‡ versus ΔS‡ is linear, suggesting a common mechanism for all the substrates. In the oxidation of para-substituted toluenes, a linear correlation between log k2 and σ0 values is observed, consistent with a benzyl radical intermediate. A linear correlation between ΔG‡ and ΔH0 (the difference between the strength of the bond being broken and that being formed in a H-atom transfer step) is also found, which strongly supports a hydrogen atom transfer mechanism for the oxidation of these substrates by trans-[Ru VI(L)(O)2]2+. The slope of (0.61 ± 0.06) is in reasonable agreement with the theoretical slope of 0.5 predicted by Marcus theory.

Citation Format(s)

Kinetics and Mechanism of the Oxidation of Alkylaromatic Compounds by a trans-Dioxoruthenium(VI) Complex. / Lam, William W. Y.; Yiu, Shek-Man; Yiu, Douglas T. Y.; Lau, Tai-Chu; Yip, Wing-Ping; Che, Chi-Ming.

In: Inorganic Chemistry, Vol. 42, No. 24, 01.12.2003, p. 8011-8018.

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