Two oxalato-bridged copper(II) complexes of formula, [Cu2(L1)2(µ-ox)](NO3)2•H2O, 1 and [Cu2(L2)2(µ-ox)](NO3)2•H2O, 2 (ox = oxalato dianion, L1 = N,N-dimethyl,N'-benzylethane-1,2-diamine, L2 = N,N-diethyl,N'-benzylethane-1,2-diamine,) have been synthesized and characterized by elemental analyses, spectroscopic (IR, UV-Vis) data and molar conductance measurements. The crystal structure of complex 1 was determined by X-ray diffraction analysis, revealing two centrosymmetric dinuclear units. The first consists of a [Cu2(L1)2(µ-ox)(NO3)2] molecule, in which each Cu(II) center is in a square pyramidal environment, providing by two nitrogen atoms from the diamine chelating ligands plus two oxygen atoms from the oxalate in the basal plane, and an oxygen of the nitrate group in the axial position. The second unit, [Cu2(L1)2(µ-ox)(H2O)2](NO3)2 has a similar structure but the apical sites are occupied by water ligands and the nitrate anions are free from coordination. Both complexes are solvatochromic. Their solvatochromism were investigated with different solvent parameter models using SPSS/PC and DFT methodology. The solvatochromic behaviors of the complexes were also explored by TD-DFT in ethanol and acetonitrile solvents. The calculated visible absorption spectra were in accord with the experimental results.
