The infrared spectra of imidazole complexes of first transition series metal(ii) nitrates and perchlorates

The IR spectra (4000–4140 cm−1 ) of the twelve imidazole (Him) complexes [M(Him)6] (NO3)2 (M = Co, Ni, Zn); [M(Him)6](ClO4)2 (M = Mn, Fe, Co, Ni); [Zn(Him)s](ClO4)2; [Cu(Him)4X2] (X = NO3, ClO4); [Zn(Him)4(NO3)2]; [Zn(Him)4](ClO4)2 and their deuterated analogues are discussed. The ratio between the frequencies of corresponding bands in the deuterated and undeuterated species is used to assign the internal imidazole vibrations. The internal modes of the NO3− and ClO4− ions are discussed in relation to the known or proposed structures of the complexes. The metal-ligand vibrations are assigned on the grounds of the shifts which occur on imidazole deuteration and metal ion substitution.