Far infrared spectra, conformational equilibria, vibrational assignments and ab initio calculations of 2-chloroethanol

The far infrared spectrum (350-50 cm(-1)) of gaseous 2-chloroethanol, CICH2CH2OH, was recorded at a resolution of 0.10 cm(-1). The O-H torsional fundamental of the most stable gauche conformer, Gg', where the capital G refers to internal rotation around the C-C bond and the lower case g to internal rotation around the C-O bond, was observed at 344.0 cm(-1) with 'hot bands' falling to lower frequency. The 'hot bands' are believed to be caused by the O-H torsion in excited states of the C-C torsion which is observed at 147 cm(-1). The corresponding torsional modes were observed for two of the high energy trans conformers, Tg (281.4 cm(-1)) and Tt (similar to 200 cm(-1)). A number of transitions observed in the spectra of the vapor between 250 and 300 cm(-1) are assigned to the CICC bend of the Gg' (299 cm(-1)), Tt (266 cm(-1)), and Tg (250 cm(-1)) conformers with some having associated 'hot bands'. Additionally infrared spectra of the vapor, amorphous and crystalline solids were recorded, and Raman spectra of the liquid, including depolarization ratios, and of the amorphous and crystalline solids were obtained. The structural parameters, conformational stabilities, barriers to internal rotation and fundamental frequencies were obtained from ab initio calculations utilizing the RHF/6-31++G** and the MP2/6-31G** basis sets and the data are compared with the experimental results.