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

Wayne A. King; Tobin J. Marks

doi:10.1016/0020-1693(94)04265-W

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

Wayne A. King, Tobin J. Marks^*

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

50 Scopus citations

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)O^tBu, 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(L_nM-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(O^tBu)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 language	English (US)
Pages (from-to)	343-354
Number of pages	12
Journal	Inorganica Chimica Acta
Volume	229
Issue number	1-2
DOIs	https://doi.org/10.1016/0020-1693(94)04265-W
State	Published - Feb 1995

Keywords

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

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry
Materials Chemistry

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@article{02a13d35e77a4e1ba9abe630c67b8b68,

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

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.",

keywords = "Block f-element complexes, Bond enthalpies, Group 4 transition element complexes, Organyl complexes",

author = "King, {Wayne A.} and Marks, {Tobin J.}",

year = "1995",

month = feb,

doi = "10.1016/0020-1693(94)04265-W",

language = "English (US)",

volume = "229",

pages = "343--354",

journal = "Inorganica Chimica Acta",

issn = "0020-1693",

publisher = "Elsevier BV",

number = "1-2",

}

TY - JOUR

T1 - Metal-silicon bonding energetics in organo-Group 4 and organo-f-element complexes. Implications for bonding and reactivity

AU - King, Wayne A.

AU - Marks, Tobin J.

PY - 1995/2

Y1 - 1995/2

N2 - 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.

AB - 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.

KW - Block f-element complexes

KW - Bond enthalpies

KW - Group 4 transition element complexes

KW - Organyl complexes

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U2 - 10.1016/0020-1693(94)04265-W

DO - 10.1016/0020-1693(94)04265-W

M3 - Article

AN - SCOPUS:0001179727

VL - 229

SP - 343

EP - 354

JO - Inorganica Chimica Acta

JF - Inorganica Chimica Acta

SN - 0020-1693

IS - 1-2

ER -