RAMAN AND INFRARED-SPECTRA, CONFORMATIONAL STABILITY, BARRIER TO INTERNAL-ROTATION, AND AB-INITIO CALCULATIONS OF 1,1-DICHLOROMETHYL METHYL-ETHER

The Raman (3200-30 cm-1) and infrared (3200-50 cm-1) spectra of 1,1-di chloromethyl methyl ether are reported for the gas, liquid, amorphous solid and annealed polycrystalline solid. These spectral data were int erpreted on the basis that in the fluid phases there is a mixture of t rans and gauche conformers but only the trans conformer remains in the annealed solid. From the temperature-dependent relative intensity of Raman bands at 379 and 427 cm-1 in the liquid, an enthalpy difference of 656 +/- 84 cm-1 (1.88 +/- 0.24 kcal mol-1 or 7.85 +/- 1.0 kJ mol-1) was obtained with the trans conformer the more stable form. Complete vibrational assignments are made for the much more abundant trans form , and a number of fundamentals are assigned for the gauche conformer w ith the aid of ab initio computations made with the 3-21 G and 6-31G basis sets. The harmonic force fields obtained using the 3-21G basis s et are reported for both conformers together with scaled and unscaled wavenumbers and the accompanying potential energy distributions. The r esults are compared with the corresponding quantities obtained for som e similar molecules.