Knowledge Bank

The infrared and Raman spectra of cyclohexylsilane have been recorded for the fluid and solid phases. Spectral intensity changes as a function of temperature for certain of the skeletal ring vibrations indicate the existence of two conformations. These have been tentatively identified as chair conformers with the silyl substituent in the equatorial and axial positions. Sum and difference bands associated with the $SiH3$ stretching modes and the $SiH3$ torsion have been observed and give a value of $125cm-1$ for the torsion. An additional set of combination bands apparently arise from a low frequency ring vibration. The analysis of this system is underway. The infrared and Raman spectra of propylsilane have also been investigated in the gas phase. Combination bands associated with the $SiH3$ torsion give a torsional frequency of $138cm-1$, and the barrier is calculated to be 1.9 kcal/mole. Another series of combination bands appear to arise from the asymmetric skeletal torsion. Analyses of these bands and the high resolution infrared spectra are underway.