HETEROATOM DERIVATIVES OF INDENE .3. VIBRATIONAL-SPECTRA OF BENZOXAZOLE, BENZOFURAN, AND INDOLE

Wavenumbers for the fundamental vibrations of benzoxazole, benofuran, and indole in the gas phase are determined using IR and Raman spectros copy. Spectra of the liquid and solid for these molecules are also mea sured, thereby assisting with the interpretation of the vapor-phase sp ectra. The IR overtone/combination region from 1600 to 2000 cm(-1) is used to establish the wavenumbers of non-planar, hydrogenic-wagging mo des for which the active IR and Raman fundamental is weak. For modes w ith no vapor-phase observation, estimated values are obtained by apply ing corrections to the condensed-phase wavenumbers. Fundamentals showi ng evidence of being involved in Fermi resonance are identified with e stimates made of the unperturbed value where possible. The differences between the vibrational assignments of previous studies and the prese nt study are discussed.