Exceedingly facile Ph−X activation (X=Cl, Br, I) with ruthenium(II): Arresting kinetics, autocatalysis, and mechanisms

Fedor M. Miloserdov, David McKay, Bianca K. Muñoz, Hamidreza Samouei, Stuart A. Macgregor, Vladimir V. Grushin

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

[(Ph3P)3Ru(L)(H)2] (where L=H2 (1) in the presence of styrene, Ph3P (3), and N2 (4)) cleave the Ph[BOND]X bond (X=Cl, Br, I) at RT to give [(Ph3P)3RuH(X)] (2) and PhH. A combined experimental and DFT study points to [(Ph3P)3Ru(H)2] as the reactive species generated upon spontaneous loss of L from 3 and 4. The reaction of 3 with excess PhI displays striking kinetics which initially appears zeroth order in Ru. However mechanistic studies reveal that this is due to autocatalysis comprising two factors: 1) complex 2, originating from the initial PhI activation with 3, is roughly as reactive toward PhI as 3 itself; and 2) the Ph[BOND]I bond cleavage with the just-produced 2 gives rise to [(Ph3P)2RuI2], which quickly comproportionates with the still-present 3 to recover 2. Both the initial and onward activation reactions involve PPh3 dissociation, PhI coordination to Ru through I, rearrangement to a η2-PhI intermediate, and Ph[BOND]I oxidative addition.
Original languageEnglish
Pages (from-to)8466–8470
JournalAngewandte Chemie International Edition
Volume54
Issue number29
Early online date2 Jun 2015
DOIs
Publication statusPublished - 2 Jun 2015

Keywords

  • Ar-X activation
  • autocatalysis
  • DFT calculations
  • kinetics
  • ruthenium

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