Spectroscopic studies of the conformations of n-decamethyltetrasilane

Chariya A. Ernst, A. Louis Allred, Mark A Ratner

Research output: Contribution to journalArticle

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Abstract

The conformational properties of n-decamethyltetrasilane, n-Si4(CH3)10, have been studied by variable temperature NMR (1H and 13C) and vibrational (IR and Raman) spectroscopy. As in related alkane systems, the anti conformer is more stable than the gauche conformer. Values of △H0 and △S0 for the anti → gauche reaction are 2.26 ± 0.15 kJ mol-1 and △S0 = 7.82± 0.86 J K-1mol-1, respectively. Thus, the two conformers are present in comparable quantities at room temperature. At very low temperatures, broadening of the two proton resonances (SiMe2, SiMe3) occurs, but phase changes precluded the observation of decoalescence. By approximate lineshape anaylysis, the free energy of activation, △G‡, for rotation about the central SiSi bond is estimated to be ∼25 kJ mol-1.

Original languageEnglish
Pages (from-to)119-131
Number of pages13
JournalJournal of Organometallic Chemistry
Volume178
Issue number1
DOIs
Publication statusPublished - Sep 25 1979

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proton resonance
alkanes
Conformations
Raman spectroscopy
free energy
activation
nuclear magnetic resonance
Temperature
room temperature
Vibrational spectroscopy
Alkanes
Raman Spectrum Analysis
Paraffins
Free energy
temperature
Protons
Infrared spectroscopy
Chemical activation
Nuclear magnetic resonance
Observation

ASJC Scopus subject areas

  • Biochemistry
  • Chemical Engineering (miscellaneous)
  • Inorganic Chemistry
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Science (miscellaneous)
  • Materials Chemistry

Cite this

Spectroscopic studies of the conformations of n-decamethyltetrasilane. / Ernst, Chariya A.; Allred, A. Louis; Ratner, Mark A.

In: Journal of Organometallic Chemistry, Vol. 178, No. 1, 25.09.1979, p. 119-131.

Research output: Contribution to journalArticle

Ernst, Chariya A. ; Allred, A. Louis ; Ratner, Mark A. / Spectroscopic studies of the conformations of n-decamethyltetrasilane. In: Journal of Organometallic Chemistry. 1979 ; Vol. 178, No. 1. pp. 119-131.
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AB - The conformational properties of n-decamethyltetrasilane, n-Si4(CH3)10, have been studied by variable temperature NMR (1H and 13C) and vibrational (IR and Raman) spectroscopy. As in related alkane systems, the anti conformer is more stable than the gauche conformer. Values of △H0 and △S0 for the anti → gauche reaction are 2.26 ± 0.15 kJ mol-1 and △S0 = 7.82± 0.86 J K-1mol-1, respectively. Thus, the two conformers are present in comparable quantities at room temperature. At very low temperatures, broadening of the two proton resonances (SiMe2, SiMe3) occurs, but phase changes precluded the observation of decoalescence. By approximate lineshape anaylysis, the free energy of activation, △G‡, for rotation about the central SiSi bond is estimated to be ∼25 kJ mol-1.

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