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Spectra and structure of small ring compounds. Part LVII —Raman and infrared spectra, vibrational assignment and ab initio calculations of cyclopropyltrifluorosilane
Author(s) -
Little T. S.,
Qtaitat M.,
Durig J. R.,
Dakkouri M.,
Dakkouri A.
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.1250210911
Subject(s) - raman spectroscopy , chemistry , infrared , basis set , ab initio , ab initio quantum chemistry methods , molecular physics , infrared spectroscopy , normal mode , hot band , normal coordinates , force field (fiction) , molecule , spectral line , molecular vibration , computational chemistry , density functional theory , vibration , optics , physics , organic chemistry , quantum mechanics , astronomy
The Raman (3500–20 cm −1 ) and infrared (3500–40 cm −1 ) spectra of gaseous and solid cyclopropyltrifluorosilane have been recorded. Additionally, the Raman spectrum of the liquid has been recorded and qualitative depolarization ratios have been obtained. From these data a complete assignment of the normal vibrational modes is provided. The fundamental vibrational frequencies have also been calculated from ab initio Hartree‐Fock calculations with the 3–21G* basis set. The force field obtained from these calculations has been used to carry out a normal coordinate analysis with a chosen set of symmetry coordinates. The molecular structure and potential surface governing internal rotation of the SiF 3 moiety have been calculated using both the 3–21G* and 6–31G* basis sets. Additionally, the SiF 3 torsional mode has been observed in the far‐infrared spectrum of the gas as a broad band centered at 46 cm −1 and from this frequency a periodic threefold barrier to internal rotation has been determined to be 420 cm −1 (1.2 kcal mol −1 ). These results are compared with corresponding quantities for some similar molecules.