VIBRATION-SPECTRA AND NORMAL COORDINATE ANALYSIS OF CF3 COMPOUNDS .21. 2,2-DIHALOHEXAFLUOROPROPANES

The gas phase i.r. spectra and liquid phase Raman spectra of the series (CF3)2CX2 (X = F, Cl, Br, I) have been recorded. Furthermore the gas phase Raman spectrum of (CF3)2CF2, the liquid phase i.r. spectra of (CF3)2CCl2 and the solid state i.r. and Raman spectra of (CF3)2CI2 have been investigated. The spectra are assigned for C2v, symmetry. The assignment is supported by Raman polarization data, i.r. band contours and a normal coordinate analysis in which (CF3)2CH2 and (CF3)2CD2 have been included. While the spectra of (CF3)2CCl2, (CF3)2CBr2 and (CF3)2CI2 are similar, the other molecules exhibit individual vibrational behaviour. The substituent effects of the CF3 group on CF and CC stretching force constants are similar to those of a Cl atom. © 1979.