THREE-DIMENSIONAL REPRESENTATION FOR THE INTERACTION OF LOW-FREQUENCY MODES WITH THE RING-PUCKERING OF 1,3-DISILACYCLOBUTANE

$^{1}$ R. M. Irwin, J. M. Cooke, and J. Laane, J. Amer. Chem. Soc., 99, 3273 (1977)Author Institution:Analysis of the low-frequency infrared and Raman spectra of 1,3-disilacyclobutane and its $d_{4}$ derivative previously demonstrated that the ring-puckering vibration for this nonplanar molecule was coupled to the $SiH_{2}$ in-phase rocking $motion.^{1}$ Since the $SiH_{2}$ rock and ring deformation modes both give rise to combination band sequences with the ring-puckering, it is possible to determine the ring-puckering energy levels for the excited states of these vibrations. Such data is useful for investigating the interaction of the ring-puckering with the other modes. We have developed a computer program to calculate the vibrational energy levels for a three-dimensional potential energy function. This has, therefore, enabled us to evaluate the effect of the nearly harmonic $SiH_{2}$ rock and ring deformation vibrations on the highly anharmonic ring-puckering mode. The three-dimensional provided a satisfactory representation for these three low-frequency vibrations and resulted in an excellant correlation between experiemental and theoretical values