The infrared and Raman spectra of the pentafluoroethyl halides

Abstract

The infrared spectra of the pentafluoroethyl halides have been investigated in the gaseous state with double-beam prism spectrometers using NaCl and CaF2 prisms, and the Raman spectra of the compounds have been obtained for both the gaseous and liquid state. Depolarization ratios were determined for the Raman spectra of the liquids. All eighteen fundamental frequencies have been identified and assigned with the help of the correlation among the spectra of the three compounds. The barrier heights of the potentials hindering internal rotation have been calculated from the observed torsional frequencies assuming rigid groups. An empirical correlation has been observed between the amount of overlap of the fluorine and halogen atoms on the two end groups of the molecule and the contribution of the fluorine-halogen interaction to the barrier height.