Molecular structure and conformational preferences of 1-bromo-1- silacyclohexane, CH 2(CH 2CH 2) 2SiH-Br, as studies by gas-phase electron diffraction and quantum chemistry

A. V. Belyakov*, A. A. Baskakov, V. N. Naraev, A. N. Rykov, H. Oberhammer, I. Arnason, S. O. Wallevik

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The molecular structure of axial and equatorial conformer of the 1-bromo-1-silacyclohexane molecule, CH 2(CH 2CH 2) 2SiH-Br, as well as thermodynamic equilibrium between these species are investigated by means of gas-phase electron diffraction and quantum chemistry on the MP2(full)/SDB-AUG-cc-PVTZ level of theory. It is revealed that according to electron diffraction data, the compound exists in the gasphase as a mixture of conformers possessing the chair conformation of the six-membered ring and C s symmetry and differing in the axial and equatorial position of the Si-Br bond (ax. = 80(5) mol %, eq. = 20(7) mol %) at 352 K, that corresponds to the value of A = (G ax ° - G eq ° ) = -0.82(32) kcal/mol. It is found that observed data agree well with theoretical ones. Using Natural Bond Orbital (NBO) analysis it is revealed that axial conformer of 1-bromo-1-silacyclohexane molecule is an example of the stabilization of the form that is unfavorable from the point of view of steric effects and effects of conjugations. It is concluded that stabilization is achieved due to electrostatic interactions.

Original languageEnglish
Pages (from-to)1563-1566
Number of pages4
JournalRussian Journal of Physical Chemistry A
Volume86
Issue number10
DOIs
Publication statusPublished - Oct 2012

Other keywords

  • conformational analysis
  • gas-phase electron diffraction
  • molecular structure
  • NBO-analysis
  • quantum-chemical calculations
  • substituted silacyclohexanes

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