Synthesis, crystal structure, magnetic and electrochemical studies of two copper complexes with carboxylate rich dinucleating ligand

Three new copper compounds of a symmetric dinucleating ligand, N,N′-bis[2-carboxybenzomethyl]-N,N′-bis[carboxymethyl]-1,3-diaminopropan-2-ol (H5ccdp) with diverse coordinating groups, have been synthesized and studied in the solid state as well as in solution. In acetonitrile/H2O solution, the reaction of stoichiometric amounts of Cu(NO3)2·2.5H2O and the ligand H5ccdp, in the presence of K2CO3, produced a dinuclear copper compound, K3[Cu2(ccdp)(μ-CO3)]·7H2O·C3H6O, K3[1]·7H2O·C3H6O. Whereas in an alkaline methanol/water solution, the reaction of Cu(ClO4)2·6H2O and the ligand H5ccdp gave a slightly different dinuclear copper compound, Na3[Cu2(ccdp)(μ-CO3)]·5H2O, Na3[1]·5H2O. The reaction of Cu(ClO4)2·6H2O and the ligand H5ccdp, in the presence of NaOH in water yielded a tetranuclear copper compound, Na2[Cu2(ccdp)(H2O)(μ-OH2)]2·15H2O, Na2[2]·15H2O. The structures of the all three complexes were determined using single crystal X-ray diffraction analyses. Variable-temperature magnetic susceptibility studies on the powder samples of the complexes showed antiferromagnetic behavior. Electrochemical studies in aqueous solutions of these negatively charged complex ions showed fairly assessable oxidations.