Fourier transform infrared spectra (4000-200 cm(-1)) are reported for the metal (II) halide isonicotinamide complexes of the following stoichiometries: M(iso)(2)X-2 [M=Ni, Cu, Hg; X=Cl; iso=isonicotinamide], M(iso)(2)X-2 [M=Ni, Cu; X=Br], and CO(iso)(2)I-2. Vibrational assignments are given for all the observed bands. The Raman spectra (4000-100 cm(-1)) are reported for the three of these complexes. Also, the ESR spectra of these complexes are given. For a given series of isomorphous complexes the sum of the difference between the values of the vibrational modes of the free isonicotinamide and complexed ligand was found to increase in the order of the second ionization potentials of metals. The frequency shifts are also found to depend on the halogen. The studied metal halide complexes were characterized by X-ray powder diffraction patterns and FTIR spectra. Certain chemical formulas were determined using elemental analysis results. Finally, the geometry optimization method was used to predict three dimensional molecular geometries of the complexes by using the HYPERCHEM 5.0 the level of the theory molecular mechanic. (c) 2005 Elsevier B.V. All rights reserved.