Spectral Features of M-CN Complexes

The most distinctive spectral property of the cyanide ligand is the strong infrared band. Cyanide complexes exhibit strong bands over a fairly narrow frequency range— 

Free and coordinated CN can also be detected by C NMR spectroscopy. The NMR chemical shift of [Me N][CN] in CDjCN is 167 ppmT A series of homoleptic cyanide complexes were shown to have C NMR chemical shifts that range from a value of 84 ppm for [Pt(CN)J to 177 ppm for [Fe(CN)J . The N chemical shifts for KCN is 106 ppm (vs. S = 0 ppm for nitromethane), but few values for coordinated cyanide have been measured.  

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