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 spectroscopy. Spectra of the liquid and solid for these molecules are also measured, thereby assisting with the interpretation of the vapor-phase spectra. The IR overtone/combination region from 1600 to 2000 cm(-1) is used to establish the wavenumbers of non-planar, hydrogenic-wagging modes for which the active IR and Raman fundamental is weak. For modes with no vapor-phase observation, estimated values are obtained by applying corrections to the condensed-phase wavenumbers. Fundamentals showing evidence of being involved in Fermi resonance are identified with estimates made of the unperturbed value where possible. The differences between the vibrational assignments of previous studies and the present study are discussed.