Two new oxalato complexes of the formula [Cu2(L)2(m-ox)(MeOH)2](ClO4)2 (1) and [Cu2(L)2(m-ox)](NO3)2 (2), where ox = oxalato and L = N,N0-dibenzylethane-1,2-diamine, were prepared and characterized by elemental analysis, IR and UV–vis spectroscopies and molar conductance measurements. The crystal structure of compound 1 was determined by single-crystal X-ray analysis. The compounds are solvatochromic and their solvatochromism was studied with different solvent parameter models using the stepwise multiple linear regression (SMLR) method with SPSS/PC software. It was demonstrated that the donor power of the solvent plays the most important role in the observed positive solvatochromism of the compounds. The complexes show irreversible thermochromism in solution due to the substitution of the weakly coordinated counter ions and coordinated solvents by solvent molecules
