Metal-silicon bonding energetics in organo-Group 4 and organo-f-element complexes. Implications for bonding and reactivity

Wayne A. King, Tobin J Marks

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

Metal-silicon bond disruption enthalpies have been measured for a series of U, Zr, and Sm metallocene complexes: Cp3USi(TMS)3, Cp2Zr(Cl)Si(TMS)3, Cp2Zr(Me)Si(TMS)3, Cp2Zr(TMS)Si(TMS)3, Cp2Zr(TMS)OtBu, Cp′2SmSiH(TMS)2 (Cp = η5-C5H5, Cp′ = η5-Me5C5, TMS = trimethylsilyl). Data were obtained by anaerobic batch-titration solution calorimetry in toluene. Derived metal-ligand bond enthalpies D(LnM-R) in kcal mol-1 are: D[Cp3USi(TMS)3] = 37(3), D[Cp2(Cl)ZrSi(TMS)3]=57(3), D[Cp2(Me)ZrSi(TMS)3]=56(5), D[Cp2(Si(TMS)3)ZrMe] = 66(5), D[Cp2(OtBu)Zr-TMS] = 60(5), D[Cp2(TMS)ZrSi(TMS)3] = 42(11), D[Cp2(Si(TMS)3)Zr-TMS] = 45(7), D[Cp′2SmSiH(TMS)2] = 43(5). These results show that metal-silicon bond disruption enthalpies involving these electron-deficient metals are substantially smaller than those of the corresponding metal hydride and hydrocarbyl bonds. These data in combination with previously measured metal-ligand bond enthalpies allow thermodynamic analyses of a variety of stoichiometric and catalytic transformations involving metal silyl functionalities. The latter include potential pathways for dehydrogenative silane polymerization, dehydrogenative silane-hydrocarbon coupling, olefin hydrosilylation, and dehydrogenative silane-amine coupling. It is not uncommon for there to be multiple pathways which effect the same catalytic transformation and which contain no steps having major enthalpic impediments.

Original languageEnglish
Pages (from-to)343-354
Number of pages12
JournalInorganica Chimica Acta
Volume229
Issue number1-2
DOIs
Publication statusPublished - 1995

    Fingerprint

Keywords

  • Block f-element complexes
  • Bond enthalpies
  • Group 4 transition element complexes
  • Organyl complexes

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Chemistry

Cite this