Potential Energy Surface of the Ring Puckering Motion in 1-Chloro-1-silacyclobutane

The equatorial-axial conformational equilibrium of 1-chloro-1-silacyclobutane has been investigated by microwave spectroscopy and ab initio calculations. The potential energy function of the ring puckering motion has been determined: four vibrational states are localized in the equatorial well and two vibrational states in the axial well, all the remaining higher energy states lying above the interconversion barrier. This study has shown that the equatorial conformer is more stable than the axial one by 185(40) cm(-1). This value is in good agreement with that provided by ab initio calculations using the 6-31G* basis set.