Synthesis and characterization of a binuclear coumarin-3-carboxylate copper(II) complex.

The copper(II) complex of coumarin-3-carboxylic acid (CcaH) has been prepared and characterized on the basis of elemental and thermal analysis, IR, Raman, EPR, UV-Vis reflectance and 1H-NMR spectra. A detail analysis of all spectra data is presented with particular emphasis on the elucidation of the coordination mode of the ligand and the structure of the complex. All data are consistent with a binuclear structure for the complex with four coumarin-3-carboxylates as bridges and one water ligand per copper ion. The significantly lower than the spin-only value magnetic moment of the complex and the EPR spectra at various temperature are indicative of a magnetic interaction between the two copper atoms.