Two different mononucleating ligands incorporating N-4 and N2S2 donor units, 2-(1,3-benzothiazole-2-yl-methyl)-1,3-benzothiazole (L-1) and N,N'-bis-(2-amino-phenyl)-malonamide (H2L2) were synthesized by a new method from malonyl dichloride as starting material, and their mononuclear copper(H) complexes were prepared and characterized by elemental analyses, H-1- and C-13-NMR, IR, magnetic moments and mass spectral studies. Elemental analyses, and stochiometric and spectroscopic data of the metal complexes indicate that the metal ions are coordinated to the nitrogen and sulfur atoms and the data support the proposed structure of L-1, H2L2 and their mononuclear copper(II) complexes. Moreover, the copper(IT) complexes of L-1 and H2L2 have a 1:1 metal to ligand ratio. In addition. the total energy and heat of formation calculated for complexes (2-3) by the semiempirical ZINDO/1 calculations showed that complexes 2 and 3 having penta coordinations are more stable than complexes of tetra coordinations.