Vibrational spectrum of chlorotrimethylsilane

The IR and Raman spectra of chlorotrimethylsilane (CTMS) were re-examined. Gas and liquid phase spectra were newly recorded and the analysis of the second derivatives of intensities in some complex spectral regions was carried out. The experimental study was combined with theoretical calculations at the B3LYP level with two different basis sets, i.e., 6-31G* and DZP+diff. The use of the SQM methodology, allowed us to review the assignment of the bands for ν3 (methyl deformation), ν5 (methyl rocking) and ν8 (SiC deformation) normal modes of A1 symmetry, as well as ν16, ν17 (methyl deformations) and ν20 (methyl rocking) normal modes of E symmetry. The description of the asymmetric CH stretchings spectral region has been improved and, in addition, new values of vibrational frequencies were predicted for A2 normal modes, inactive in both IR and Raman spectra. The equilibrium geometry parameters of CTMS obtained in this work at the MP2/DZP+diff level are closer to the experimental values than previous predictions.