Infrared and Raman Spectra, Vibrational Assignment, Normal Coordinate Analysis, and Barrier to Internal Rotation of N-Chloro-N-methylmethanamine

Article abstract of DOI:10.1021/j100303a028

The infrared (3200-80 cm^-1) and Raman (3200-10 cm^-1) spectra have been recorded of gaseous and solid N-chloro-N-methylmethanamine (dimethylchloroamine), (CH3)2NCl, and the corresponding deuterium molecules, CH3(CD3)NCl and (CD3)2NCl.Additionally, the Raman spectra of the liquids have been recorded and qualitative depolarization values have been obtained.A complete vibrational assignment is proposed, based on the infrared band contours, Raman depolarization values, group frequencies, and isotopic shifts.The assignment is supported by a normal coordinate analysis which was carried out by utilizing a modified valence force field to calculate the frequencies and the potential energy distribution.The A' and A" methyl torsional fundamentals were observed in the infrared spectrum in the gas phase of the d₀ molecule at 281 and 261 cm^-1, respectively, from which the threefold barrier to internal rotation is calculated to be 1658 cm^-1 (4.74 kcal/mol).From the number of lattice modes observed in the Raman spectrum of the solid, it is concluded that there are at least two molecules per permitive cell.All of these results are compared to similar quantities of some corresponding molecules.