Vibrational spectra and structure of benzophenone and its (18)O and d10 labelled derivatives: an ab initio and experimental study.

Infrared (4000-100 cm(-1)) and Raman (4000-10 cm(-1)) spectra of benzophenone, benzophenone-d10 and benzophenone-(18)O have been studied in the solid state and in solution and their fundamental frequencies have been assigned using isotopic frequency shifts and differential infrared linear dichroic spectra of oriented polycrystalline layers (4000-400 cm(-1)). Ab initio MO calculations have been carried out for the three benzophenone isotopomers at the HF/3-21G, 6-31G and 6-31G** levels and the computed vibrational frequencies have been compared with the experimental ones. Best agreement is achieved with the 6-31G data, the mean deviation being 25.4 cm(-1). The calculated isotopic frequency shifts induced by the (18)O and d10 labelling, are also in a good accordance with the measured ones. All geometry parameters calculated for the isolated molecule are in good agreement with the X-ray data for the benzophenone single crystal.