The rate and mechanism of oxidative addition of H2 to the ·Cr(CO)3C5Me5 radical - Generation of a model for reaction of H2 with the ·Co(CO)4 radical

Kenneth B. Capps, Andreas Bauer, Gabor Kiss, Carl Hoff

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The rate of reaction of hydrogen with the 17 e- metal centered radical ·Cr(CO)3C5Me5 obeys the third-order rate law d[P]/dt=kobs[·Cr]2[H2] in toluene solution. In the temperature range 20-60°C, kobs=330±30 M-2 s-1, ΔH=0±1 kcal mol-1, ΔS=-47±3 cal mol-1 deg-1. The rate of oxidative addition is not inhibited by added pressure of CO. The rate of binding of D2 is slower than that of H2: k(H2)/k(D2)=1.18. These results are combined with earlier work to generate a complete reaction profile for hydrogenation of the metal-metal bonded dimer [Cr(CO)3C5Me5]2+H 2→2H-Cr(CO)3C5Me5. A similar reaction profile for Co2(CO)8+H2→2H-Co(CO)4 under high pressures of CO is constructed based on literature data and estimated activation parameters for reaction of the ·Co(CO)4 radical with hydrogen.

Original languageEnglish
Pages (from-to)23-30
Number of pages8
JournalJournal of Organometallic Chemistry
Volume586
Issue number1
StatePublished - Jul 31 1999

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Metals
Hydrogen
Pressure
Hydrogenation
Toluene
metals
Dimers
hydrogen
profiles
Chemical activation
hydrogenation
toluene
Temperature
dimers
activation
temperature

Keywords

  • Chromium
  • Cobalt
  • Free radicals
  • Hydrogen
  • Oxidative addition

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Chemistry

Cite this

The rate and mechanism of oxidative addition of H2 to the ·Cr(CO)3C5Me5 radical - Generation of a model for reaction of H2 with the ·Co(CO)4 radical. / Capps, Kenneth B.; Bauer, Andreas; Kiss, Gabor; Hoff, Carl.

In: Journal of Organometallic Chemistry, Vol. 586, No. 1, 31.07.1999, p. 23-30.

Research output: Contribution to journalArticle

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AB - The rate of reaction of hydrogen with the 17 e- metal centered radical ·Cr(CO)3C5Me5 obeys the third-order rate law d[P]/dt=kobs[·Cr]2[H2] in toluene solution. In the temperature range 20-60°C, kobs=330±30 M-2 s-1, ΔH≠=0±1 kcal mol-1, ΔS≠=-47±3 cal mol-1 deg-1. The rate of oxidative addition is not inhibited by added pressure of CO. The rate of binding of D2 is slower than that of H2: k(H2)/k(D2)=1.18. These results are combined with earlier work to generate a complete reaction profile for hydrogenation of the metal-metal bonded dimer [Cr(CO)3C5Me5]2+H 2→2H-Cr(CO)3C5Me5. A similar reaction profile for Co2(CO)8+H2→2H-Co(CO)4 under high pressures of CO is constructed based on literature data and estimated activation parameters for reaction of the ·Co(CO)4 radical with hydrogen.

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