RESONANCE RAMAN-SPECTRA AND NORMAL-MODES OF VIBRATION OF 2,2-'-BIPYRIDINE ANION RADICALS

The resonance Raman spectra of the lithium complexes of the 2,2′‐bipyridine anion radical and five isotopically labeled analogues, including the 15N‐labeled species, are reported. All of the fundamental modes of vibration, excluding the CH stretching and several low‐frequency modes, have been identified. Care must be taken to avoid contamination of the sample with the dianion Li2bpy. In order to eliminate possible misassignment of bands to traces of Li2bpy, the spectra of the latter species were also investigated. The assignments of the vibrational frequencies to the fundamental modes of Libpy are supported by a normal coordinate calculation and the structural implications of the vibrational frequency shifts, relative to the neutral parent, are discussed. Copyright © 1990 John Wiley & Sons, Ltd.