Infrared and Raman spectra, vibrational assignment, and ab initio calculations of fluoromalononitrile

Article abstract of DOI:10.1016/S1386-1425(97)00119-4

The infrared spectra (3500-80 cm^-1) of gaseous and solid and the Raman spectra (3500-30 cm^-1) of liquid with quantitative depolarization values and solid fluoromalononitrile, FHC(CN)₂, have been recorded. These spectra have been interpreted in detail and a complete vibrational assignment is proposed based on infrared band contours, depolarization values, and relative infrared and Raman intensities. The assignment is supported by a normal coordinate calculation based upon force constants obtained from MP2/6-31G* ab initio calculations. Also, from these calculations the predicted infrared and Raman spectra have been obtained. The C-H bond distance is predicted to be 1.096 A from the isolated carbon-hydrogen stretching frequency. Optimized geometric parameters have been obtained from RHF/6-31G*, MP2/6-31G* and MP2/6-311 + + G** ab initio calculations. These results are discussed and compared with those obtained for some similar molecules.