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Vibrational spectra and structure of tricyclopropylsilane
Author(s) -
Wurrey Charles J.,
Holder Andrew J.,
Green Peter M.
Publication year - 1990
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250210906
Subject(s) - conformational isomerism , raman spectroscopy , cyclopropane , molecule , chemistry , infrared , spectral line , crystallography , infrared spectroscopy , gauche effect , ring (chemistry) , physics , optics , organic chemistry , medicine , surgery , astronomy
Abstract The Raman spectra of tricyclopropylsilane were recorded for the condensed phases of this molecule, and infrared spectra (4000–400 cm −1 ) were obtained for all three states of this compound. In addition, a survey microwave spectrum of tricyclopropylsilane was recorded in the R ‐band region, and AM1 semi‐empirical calculations were aslo undetaken for this molecule. Both the spectroscopic data and the theoretical results indicate that tricyclopropylsilane does not exhibit any low‐energy structure having threefold symmetry. Instead, experimental evidence indicates the presence of at least two conformers of this molecule in the fluid phases, and only one of these conformers remains in the polycrystalline solid phase. The Raman and infrared spectra argue in favor of the fluid‐phase tricyclopropylsilane conformers having the three cyclopropane rings arranged in a mixture of s – cis and gauche orientations relative to the SiH bond. These conclusions appear to be corroborated by the AM1 calculations, which indicate that the cis – cis – gauche rotamer of tricyclopropylsilane is the lowest in energy, followed by the cis – gauche – gauche and cis – gauche – gauche ′ conformations, which are virtually equal in energy.