Polarized IR and DFT study of the fundamental vibrations of xanthone

The polarized infrared spectrum of xanthone embedded in a stretched polyeth ylene film has been measured. Orientation factors obtained fi om dichroic r atios have been determined for 20 transitions. Symmetry assignments derived from the polarization data are in excellent agreement with the predictions of scaled B3-LYP/6-31G(d) density functional theory calculations. The unpo larized infrared spectrum of xanthone in KBr has also been recorded. A comb ination of polarized and unpolarized infrared data, published Raman results , and B3-LYP/6-31G(d) predictions have been used to assign the fundamental vibrational frequencies of xanthone. These new results clarify some ambigui ties found in the previous studies and have led to the reassignment of seve ral vibrations. (C) 2000 Elsevier Science B.V. All rights reserved.