Raman spectra of gases. XIX–The low frequency gaseous phase Raman spectra and the barriers to internal rotation of the 1,1,1‐trifluoroethyl halides

Abstract

Abstract The gaseous phase Raman spectra of CF 3 CH 2 I, CF 3 CH 2 Br, CF 3 CH 2 CI and CF 3 CH 2 F have been investigated and the barriers to internal rotation determined. The torsional fundamentals were observed to be unusually strong, depolarized bands, and several Δν = 2 torsional transitions were measured for all compounds. Torsional transitions originating from excited states of the skeletal bend were also observed for CF 3 CH 2 CI and CF 3 CH 2 F. The torsional barriers found were: CF 3 CH 2 I, 4.16 ± 0.11; CF 3 CH 2 Br, 4.39 ± 0.07; CF 3 CH 2 CI, 4.88 ± 0.03 and CF 3 CH 2 F, 3.58 ± 0.14 kcal mol −1 .