Reactions of the complexes M(Pr3)2(CO)3(M = Cr, Mo, W; R = iPr, Cy) with thiols, hydrogen sulfide, disulfides, hydrogen iodide and iodine. The role of heteroatoms in determining the metal-hydrogen bond strength at a sterically crowded metal center

Russel F. Lang, Telvin D. Ju, Gabor Kiss, Carl D. Hoff, Jeffrey C. Bryan, Gregory J. Kubas

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

The complexes M(PCy3)2(CO)3 (M = Cr, Mo, W) react with phenyl disulfide to form stable 17-electron radical complexes .M(PCy3)2(CO)3(SPh). Reaction with other alkyl and aryl disulfides also yields stable radicals and reaction with I2 yields .W(PiPr3)2(CO)3(I). Reaction with thiols, hydrogen sulfide and hydrogen iodide yield the corresponding 18-electron hydrides W(PiPr3)2(CO)3(H)(X). The crystal structure of W(PiPr3)2(CO)3(H)(I) is reported and allows comparison with the structure of the radical complex .W(PiPr3)2(CO)3(I). The W-H bond strengths in these heteroatom complexes are low, 55-57 kcal mol-1. In spite of steric crowding, H atom transfer from W(PiPr3)2(CO)3(H)(SPh) to .Cr(CO)2(PPh3)Cp occurs readily due to the stronger nature of the Cr-H bond formed. The chromium radical does not appear to attack the molecular hydrogen complex W(Pr3)2(CO)3(H2) or its dihydride form W(Pr3)2(CO)3(H)2 based on rate of hydrogenation studies. Phenyl disulfide does react with either W(Pr3)2(CO)3(H2) or its dihydride tautomer W(Pr3)2(CO)3(H)2 to form thiophenol and W(Pr3)2(CO)3(SPh.). This reaction is proposed to proceed by reaction of .SPh radicals which are generated in situ. These studies are used to bracket the first W-H bond dissociation energy in W(Pr3)2(CO)3(H)2. Additional studies of H atom and heteoratom transfer are described.

Original languageEnglish (US)
Pages (from-to)317-327
Number of pages11
JournalInorganica Chimica Acta
Volume259
Issue number1-2
DOIs
StatePublished - Jun 1997

Keywords

  • Chromium complexes
  • Hydrogen sulfide complexes
  • Molybdenum complexes
  • Thiol complexes
  • Tungsten complexes

ASJC Scopus subject areas

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

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