Spectra and Structure of Silicon-Containing Compounds. XXVIII1 Infrared and Raman Spectra, Vibrational Assignment, and Ab Initio Calculations of Vibrational Spectrum and Structural Parameters of Vinyltrichlorosilane

Abstract

The infrared spectra (3200-50 cm−1) of gaseous and solid vinyltrichlorosilane, CH2=CH-SiCl3, have been recorded. In addition, the Raman spectrum (3200-10 cm−1) of the liquid has been recorded and quantitative depolarization values obtained. The infrared spectrum of the sample dissolved in liquid xenon (−80°C) has also been recorded. Using the experimental data and normal coordinate calculations with scaled ab initio force constants, the complete vibrational assignment is proposed. The torsional mode was observed in the infrared spectrum of the gas at 69 cm−1 and the threefold barrier of internal rotation was calculated to be 500 cm−1 (5.98 kJ/mol). Ab initio calculations have been carried out at the restricted Hartree–Fock level of the theory as well as with full electron correlation by the perturbation method to second order with different basis sets up to 6-311+G(d,p) to obtain the optimized geometries, harmonic force constants, infrared intensities, Raman activities, depolarization ratios, and vibrational frequencies. The ab initio predicted structural parameters are compared with those obtained from a previous electron diffraction study.