Coordination behaviour of nicotinamide:: an infrared spectroscopic study

A series of Hofmann-type complexes containing two nicotinamide(nia) molecules attached to transition metal (II) (M) tetracyanonickelate frame with the formula: M(nia)(2)Ni(CN)(4) (where M = Mn, Co, Ni, Cu or Cd) have been synthesised for the first time. Metal (II) halide complexes of nicotinamide complexes of the type [M(nia)(2)X-2 (M = Cd, Ni, Cu, Hg; X = Cl, Br) and Ni(nia)(4)Br-2 nia = nicotinamide] have also synthesised. The FTIR spectra are reported in the 4000-400 cm(-1) region. Vibrational assignments are given for all the observed bands. The analysis of the vibrational spectra indicates that there are some structure-spectra correlations. A pronounced change was observed in the N-H stretching frequencies of the NH2 group. It is proposed that the amide NH2 group influence by the intramolecular hydrogen bond in the complexes. The coordination effect on the nicotinamide modes is analysed. (C) 2003 Elsevier Science B.V. All rights reserved.