Synthesis, crystal structure, EPR and electrochemical studies of copper(II) dipicolinate complex with 2,2′-dipyridylamine ligand

The (2,2'-dipyridylamine)(pyridiiie-2,6-dicarboxylato)copper(II) trihydrate complex was synthesized and characterized by spectroscopic (IR, UV-vis, EPR), X-ray diffraction technique and electrochemical methods. The copper(II) center is surrounded by one bidentate 2,2'-dipyridylamine (dpa) and one tridentate dipicolinate (dpc) ligand, Lind exhibits a distorted square-pyramidal geometry. The crystal packing involves both hydrogen-bonding and pi-pi interactions. The solvent water molecules link monomers to one another through hydrogcn-bonding interactions, forming ladder-type chains in the ab plane. pi-pi interactions also occur between the dpa rings of neighboring molecules and are responsible for interchain packing. Based on EPR and optical absorption studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values, calculated for title complex in polycrystalline state at 298 K and in frozen DNIF (I 10 K), indicate the presence of the unpaired electron in the d,(x2-x2) orbital. The evaluated metal-ligand bonding parameters showed strong in-plane sigma- and pi-bonding. The cyclic voltammogram of the title complex investigated in DMF (dimethylformamide) solution exhibits only metal centered electroactivity in the potential range +1.25 V versus Ag/AgCl reference electrode. (c) 2007 Elsevier Ltd. All rights reserved.