VIBRATIONAL ASSIGNMENTS AND RING-PUCKERING POTENTIAL FUNCTIONS FOR CYCLOBUTANE AND CYCLOBUTANE-$d_{8}$

Author Institution: Department of Chemistry, University of PittsburghInfrared spectra of gaseous and solid cyclobutane and cyclobutane-$d_{8}$ have been recorded from 200 to $4000 cm^{-1}$. Raman spectra of both compounds were obtained for the gas, liquid and solid phases. The assignments will be discussed on the basis of the equilibrium configuration, $D_{2d}$. Four gas-phase Raman bands have been observed for the pure ring-puckering mode of $C_{4} H_{8}$ and six for $C_{4} D_{8}$ between 90 and $200 cm^{-1}$. These frequencies (as well as ring-puckering frequencies evaluated from combination tones in the mid-infrared spectrum of $C_{4} H_{8}$) were fitted to a potential function of the form V(x) = a($x^{4}-bx^{2}$), where x is the ring-puckering coordinate. The barriers to inversion in $C_{4} H_{8}$ and $C_{4} D_{8}$ are $518\pm 5 cm^{-1}$ and $508\pm 8 cm^{-1}$ respectively