In this study, infrared (4000-200 cm(-1)) spectra are reported for the metal (11) halide isonicotinamide complexes of the following stoichiometries: M(iSO)(2)X-2 (M = CO, Mn, Zn; X = Cl, Br; iso = isonicotinamide) and M(iSO)X-2 (M = Zn; Cu, X = I; M = Hg, X = Br). Vibrational assignments are given for all the observed bands. The analysis of the vibrational spectra indicates that there are some structure-spectra correlations. For a given series of isomorphous complexes the sum of the difference between the values of the vibrational modes of uncoordinated isonicotinamide and coordinated to metal ion isonicotinamide was found to increase in the order of the second ionization potentials of metals. The frequency shifts were also found to depend on the halogen. The studied metal halide complexes were characterized by X-ray powder diffraction patterns and FT-IR spectra. Certain chemical formulas were determined using elemental analysis results. (C) 2002 Elsevier Science B.V. All rights reserved.