SEMIEMPIRICAL AND VIBRATIONAL STUDIES OF FLAVONE AND SOME DEUTERATED ANALOGS

The infrared solid state, Raman solid state and tetrachloride solution spectra of flavone have been obtained. Assignments of most of the vib rational data have been performed by comparison between the spectra of flavone and three isotopic species, deuterated on the A, B and C ring s, respectively. The vibrational frequencies for all the investigated compounds have been calculated from the conformational analysis of fla vone using the semi-empirical AM1 method and compared with experimenta l values. The correlation is more or less satisfactory; however, for s ome vibrational modes, the calculated isotopic shifts agree better wit h experiment than do the frequencies themselves, Specific vibrational modes which retain a benzene ring monosubstituted and ortho-distribute d character have been recognized in the spectra, according to literatu re data, isotopic frequency shifts and graphic representation of the a tomic displacements.