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Raman and infrared spectra, vibrational assignments and barriers to internal rotation of cis ‐ and trans ‐1‐chloropropene
Author(s) -
Durig J. R.,
Guirgis G. A.
Publication year - 1982
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.1250130212
Subject(s) - overtone , raman spectroscopy , infrared , molecule , chemistry , spectral line , infrared spectroscopy , internal rotation , analytical chemistry (journal) , molecular physics , optics , physics , organic chemistry , mechanical engineering , astronomy , engineering
The Raman spectra of both cis ‐ and trans ‐1‐chloropropene were obtained between 3500 and 20 cm −1 for the vapor, liquid and solid states and the polarization data were obtained for the fluid phases. The infrared spectra were recorded between 3500 and 50 cm −1 for both compounds in the vapor and solid states. Complete vibrational assignments based on depolarization data, infrared band contours and group frequencies are presented for both molecules on the basis of C s symmetry. The methyl torsion for trans ‐1‐chloropropene was observed in the infrared spectrum of the vapor as a series of transitions with the 1 ← 0 fundamental having a frequency of 208 cm −1 ; from this fundamental frequency a periodic barrier to internal rotation was calculated to be 844±16 cm −1 (2413±46 cal mol −1 ). Although the methyl torsion was not observed directly for cis ‐1‐chloropropene, the first overtone was tentatively assigned in the Raman spectrum of the vapor at 205 cm −1 . Many of the fundamentals for both the cis and trans molecule appear as doublets in the spectra of the solids which indicates that there are at least two molecules per primitive cell for each solid. These results are compared to corresponding quantities in some similar molecules.