Experimental and ab initio theoretical vibrational spectra of 3,3-dimethyl-1,2-bis(trimethylsilyl)cyclopropene

Yu.N. Panchenko, G.R. De Mare, A.V. Abramenkov, M.S. Baird, V.V. Tverezovsky, A.V. Nizovtsev, I.G. Bolesov

Spectrochim. Acta, (1999) (in print)

ABSTRACT. 3,3-Dimethyl-1,2-bis(trimethylsilyl)cyclopropene was synthesised using standard methods and its Raman and IR spectra were measured in the liquid phase. Total geometry optimisation was performed at the HF/6-31G* level and the HF/6-31G*// HF/6-31G* force field was calculated. The ab initio theoretical force field was corrected using Pulay's scaling technique by scale factors transferred from 3,3-dimethylbutene-1 and the 1-methyl-, 1,2-dimethyl-, and 3,3-dimethylcyclopropenes (17 scale factors for 105-dimensional problem). The scaled quantum-mechanical force field obtained was used to solve vibrational problem. Assignments of the experimental spectra are given. The assignments take into account the potential energy distribution and the correlation between experimental estimations of the intensities and depolarisation ratios of the bands and the theoretical values calculated using the unscaled quantum mechanical force field.

Laboratory of Molecular Spectroscopy