VIBRATIONAL-SPECTRA AND MOLECULAR MECHANICS AND AB-INITIO CALCULATIONS FOR 1,3-DIOXOLE - CONFIRMATION OF NONPLANARITY

Infrared and Raman spectra of the vapor, liquid, and solid phases of 1,3-dioxole have been recorded and analyzed. Much of the spectra can be interpreted assuming C-2v symmetry. However, several combination bands with the ring-puckering vibration along with the observation of an otherwise inactive mode confirm the non-planarity of this molecule. The observed frequencies are compared with predicted values from molecular mechanics (MM3) and ab initio (STO3-21G*) calculations. These calculated values provide useful estimates but about half of them differ from the observed values by more than 50 cm(-1). Several predicted values disagree by more than 200 cm(-1).