Infrared and Raman spectra, DFT-calculations and spectral assignments of silacyclohexane

Raman spectra of silacyclohexane as a liquid was recorded and depolarization data obtained. The infrared spectra of the vapour and liquid have been studied.The compound exists in the stable chair conformation, whereas a possible twist form should have more than 15 kJ mol−1 higher energies for silacyclohexane derived from numerous calculations. The wavenumbers of the vibrational modes were derived in the harmonic and anharmonic approximation in B3LYP/cc-pVTZ calculations. The 27 A′ and 21 A″ fundamentals were assigned on the basis of the calculations, on infrared vapour contours, Raman depolarization measurements and infrared and Raman band intensities. An average, relative deviation of ca 0.77% was found between the observed and the anharmonic wavenumbers for the 48 modes.

► Infrared and Raman spectra of silacyclohexane (c-C5H10SiH2).
► DFT calculations of vibrational modes in the anharmonic approximation.
► Assignments of the A′ and A″ fundamentals.
► Less than 0.8% relative deviation between observed and calculated modes.