Two cyanide bridged hetero-metallic complexes of general formula, (M(1,2-dmi)(2)Ni(mu-CN)(4)](n) (1,2-dmi = 1,2-dimethylimidazole and M = Zn(II) or Cd(II)) have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal analyses and elemental analyses. The crystallographic analyses reveal that the complexes, [Zn(1,2-dmi)(2)Ni(mu-CN)(4)] (1) and [Cd(1,2-dmi)(2)Ni(mu-CN)(4)] (2), have polymeric 2D networks. In the complexes, four cyanide groups of [Ni(CN)(4)](2-) coordinated to the adjacent M(II) ions and distorted octahedral geometries of complexes are completed by two nitrogen atoms of trans 1,2-dmi ligands. The structures of I and 2 are similar and linked via intermolecular hydrogen bonding, C-H center dot center dot center dot Ni interactions to give rise to 3D networks. Vibration assignments are given for all the observed bands and the spectral features also supported to the crystal structures of heteronuclear complexes. The FT-IR and Raman spectra of the complexes are very much consistent with the structural data presented. (c) 2015 Elsevier B.V. All rights reserved.