Vibrational spectra halide complexes

These considerations, however, cannot exclude the possibility that a vibration of a pyridine-halide-metal (atom or surface) complex is responsible for the debated Raman feature. This would explain the shift of the frequency from that of a metal-halide frequency, the stability to cathodic potentials" (and, perhaps, the relative insensitivity to the metal itself). One should mention in this context that Krasser et reported a band at 240 cm in the Raman spectrum of pyridine-silver cluster complexes, which they associate with a pyridine-Ag mode. 

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