A new Cu(II)/Ni(II) heterometallic cyanide-bridged complex of 1,2-dimethylimidazole (dmi), [Cu(dmi)(2)-Ni(mu-CN)(4)](n) was synthesized and its structure was characterized by FT-IR, Raman, single-crystal X-ray diffraction (SC-XRD) and thermal/elemental analysis techniques. In our previous study, we reported cyanide-bridged zinc(II) and cadmium(II) complexes with 1,2-dimethylimidazole (dmi), [M(dmi)(2)Ni(mu-CN)(4)](n) (M(II) = Zn or Cd), and determined their structures, experimentally. The crystallographic analyses reveal that the complexes 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 the complexes are completed by two nitrogen atoms of trans dmi ligands. The structures of the complexes similar and linked via intermolecular hydrogen bonding, C-H center dot center dot center dot Ni interactions to give rise to 3D networks. The optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the complexes were examined by means of the density functional theory (DFT) method, the Becke-3-Lee-Yang-Parr (B3LYP) functional and the LANL2DZ basis set. Additionally, the optimized geometries were investigated with time depended density functional theory (TD-DFT) method and the LANL2DZ basis set on the singlet and triplet states in order to obtain electronic transitions. These results were provided the electronic behaviors during the excitations on the complexes and dmi. (C) 2019 Elsevier B.V. All rights reserved.