POTENTIAL FUNCTION FOR LOW-FREQUENCY BENDING MODE OF SILYLISOCYANATE

The infrared spectral (3500-200 cm-1) for H3SiNCO and D3SiNCO in the vapor and solid states and the Raman spectra (3000-50 cm-1) for all three physical states have been recorded. The Raman spectra of the gas-phase samples exhibit a number of Q branches between 90 and 150 cm-1 which have been assigned to the double quantum transitions associated with the skeletal bending mode of a quasilinear molecule. An anharmonic potential of the form V = Aq4 + Bq2 has been used to adequately explain the observed spectra, and the values for the potential constants are A = 0.858 and B = -12.5 for the light" species and A = 0.780 and B = -11.9 for the "heavy" isotope. These potential surfaces indicate a barrier of 45 cm-1 at the linear skeletal configuration with only two vibrational levels below the barrier. The potential function and barrier are discussed in the context of previous studies. © 1978 American Institute of Physics."