VIBRATIONAL ASSIGNMENT OF IN-PLANE AND OUT-OF-PLANE MODES OF SOME AROMATIC AND ARYLALIPHATIC KETONES

IR and Raman spectra of some benzophenones, deoxybenzoines, benzils and antraquinone have been measured in solid state and in solution in the 4000-100 cm(-1) frequency range. The IR and Raman spectra of the synthesized corresponding O-18-labelled isotopic isomers have also been studied in the same frequency region. The unambiguous assignment of these bands was performed on the basis of the O-16-O-18 isotopic shifts. It was found that whereas the isotopic effect in the arylaliphatic ketones affects more vibrations than the carbonyl fundamentals the bands of the in- and out-of-plane carbonyl vibrations of the aromatic ketone are characteristic. The latter is due to the fact that isotopic effect is lokalized on them only. In contrast to the stretching vibrations of the C=O group of some compounds investigated which correlate satisfactorily with sigma-constants no correlations with any type of the same constants was observed for the delta(C=O) and gamma(C=O) frequencies. Whereas the frequencies of in-plane C=O modes of the measured ketones are in 605-461 cm(-1) region, the corresponding out-of-plane vibrations he between 509 and 285 cm(-1). The IR and Raman band assignment of in- and out-of-plane vibrations of the C=O group reported were reinterpreted on the basis of data obtained.