REVISED VIBRATIONAL ANALYSIS FOR METHANETHIOL

$^{1}$J. Travert, O. Saur, A. Janin,and J. C. Lavalley, J. Mol. Struct., 1976, 33, 265; O. Saur, J. Travert, J.-C. Lavalley, and M. Chabanel, C.R. Acad. Sci. Paris, 1980, c, 291, 227. $^{2}$I.W. May and E.L. Pace, Spectrochim. Acta, 1968, 24A, 1605.Vibrational data for C-deuterated methanethiols are now $available^{1}$ to supplement those previously reported for $CH_{3}SH$ and $CH_{3}SD.^{2}$ In addition $^{13}CH_{3}SH (90$^{13}C)$has been prepared, and its vapor-phase infrared spectrum obtained. On the basis of this information, a new normal coordinate analysis of methanethiol was undertaken. The calculations used a modified valence force field in which eight diagonal (the torsional mode was neglected) and four interaction constants were simultaneously refined. This 12 parameter force field reproduced 50 observed frequencies with is average error of less than$9 cm^{-1}$(< 0.8$CD_{3}$ and CSH deformations of the C-deuterated species