ULTRAVIOLET RESONANCE RAMAN-SPECTROSCOPY AND GENERAL VALENCE FORCE-FIELD ANALYSIS OF PHENOLATE AND PHENOXYL RADICAL

Ultraviolet resonance Raman (UVRR) spectra are reported for aqueous phenolate ion, and for the phenoxyl radical, generated by photoionization of phenolate at 240 nm. O-17 labeling establishes that the dominant UVRR band, at 1505 cm(-1) is the CO stretching mode; its high frequency reflects substantial CO double bond character. Additional isotopic data, C-13(6) and d(5), are used to develop empirical force fields for phenoxyl radical and the phenolate ion. In agreement with recent ab initio calculations, a bond alternant pattern is found for the phenoxyl CC force constants, reflecting substantial quinoid character in the radical.