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Spectra and structure of organophosphorus compounds. XXXI —Raman and infrared spectra and conformational stability of ethylphonothioic dichloride
Author(s) -
Durig J. R.,
Hizer T. J.
Publication year - 1987
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.1250180608
Subject(s) - conformational isomerism , raman spectroscopy , chemistry , infrared , valence (chemistry) , enthalpy , infrared spectroscopy , molecule , analytical chemistry (journal) , spectral line , potential energy , thermodynamics , organic chemistry , atomic physics , physics , astronomy , optics
The Raman (3500–10 cm −1 ) and infrared (3500–50 cm −1 ) spectra of solid ethylphosphonothioic dichloride, CH 3 CH 2 P(S)Cl 2 , and its deuteriated analog, CD 3 CH 2 P(S)Cl 2 , have been recorded. Additionally, the Raman spectrum of the liquid has been recorded and qualitative depolarization values have been obtained. From the fact that several distinct Raman lines disappear on going from the liquid phase to the solid state, it is concluded that the molecule exists as a mixture of the trans and gauche conformers in the liquid phase with the gauche conformer being the more stable form and the only one present in the solid Gtate. A variable temperature study of the Raman spectrum of the liquid did not yield an enthalpy difference between the conformers. Relying mainly on group frequencies and relative intensities of the infrared and Raman bands, a complete vibrational assignment is proposed for the gauche conformer. This assignment is supported by a normal coordinate calculation, which was carried out utilizing a modified valence force field to obtain the frequencies of the normal modes and the potential energy distribution. All of these results are compared with corresponding quantities for several other organophosphines.