The geometrical structure of CuL2 (I), where L = R1N(O)–(O)CR2, R1 = Me, R2 = Ph, was studied by X-ray diffraction in the crystalline state and by stationary ESR spectroscopy in solution. In the crystalline state, I is a chain polynuclear complex. According to ESR data, in frozen solutions, complex I exists as three species, two being mononuclear and one being binuclear. The magnetic resonance parameters and concentrations of the species in frozen solutions were determined. The electronic structure of the complex with full geometry optimization of all systems was calculated in terms of the unrestricted density functional theory (DFT) method.