New hetero-binuclear Hg-Cu Schiff base complexes were prepared by reaction of 2,2'-[1,1'-(2,2-dimethylpropane-1,3-diyldinitrilo)-diethyldyne]diphenolato}copper(II) (CuL1) and 6,6'-X-2,2'-[(2,2-dimethylpropane-1,3-diyl)bis(nitrilomethanylylidene)]diphenolato copper(II) [(X = ethoxy (CuL2) and methoxy (CuL3)], with HgCl2 to give [Cu(L1)HgCl2] (1), [Cu(L2)HgCl2] (2), and [Cu(L3)HgCl2] (3), respectively. In the precursor Cu(II) complexes (CuL1-CuL3), the coordinated phenolic oxygen atoms and those of the substituents at 3,3'-positions (in 2 and 3) on aromatic ring can act as additional site of coordination to HgCl2 as metallo-ligand to make heterobinuclear Cu-Hg complexes. The H2L1, H2L2, and H2L3 Schiff base ligands were characterized by elemental analyses, 1H NMR and FT IR techniques. The related binuclear Cu-Hg complexes were characterized by elemental analyses and single-crystal X-ray diffraction. The main coordination sites for the HgCl2 unit are phenolic oxygen atoms and there are also short intramolecular Hg…O (methoxy, and ethoxy segments) contacts in 2 and 3. The crystal packing of 3 shows one-dimensional extended chains along the b-axis through pair of centro-symmetric C–H…Cl interactions. The new complexes crystallize in Pbca (1), P21/n (2), and P21/c (3) space groups.