Crystal Structure and EPR Studies of Mixed Ligand Complex of Cobalt(II) with Saccharin and Ethylisonicotine

Abstract

The tetraaquabis(ethylisonicotinate)cobalt(II) disaccharinate, [Co(ein)<inf>2</inf>(H<inf>2</inf>O)<inf>4</inf>]·(sac)<inf>2</inf>, (CENS), (ein: ethylisonicotinate and sac: saccharinate) complex has been synthesized and its crystal structure has been determined by X-ray diffraction analysis. The title complex crystallizes in monoclinic system with space group P2<inf>1</inf>/c and Z = 2. The Co(II) cations present a slightly distorted CoN<inf>2</inf>O<inf>4</inf> octahedral environment, with equatorially coordinated water molecules and axially pyridine N-bound ethylisonicotinate ligands. The magnetic environments of Cu2+-doped Co(II) complex have been identified by electron paramagnetic resonance (EPR) technique. Cu2+-doped CENS single crystals have been studied at room temperature in three mutually perpendicular planes. The calculated results of the Cu2+-doped CENS indicate that Cu2+ ion substitute with the Co2+ ion in the host lattice. The angular variations of the EPR spectra have shown that two different Cu2+ complexes are located in different chemical environments, and each environment contains two magnetically inequvalent Cu2+sites in distinct orientations occupying substitutional positions in the lattice and show very high angular dependence. The cyclic voltammogram of the title complex investigated in dimethylformamide (DMF) solution exhibits only metal centerd electroactivity in the potential range -1.0-1.25 V versus Ag/AgCl reference electrode. © 2008 Elsevier B.V. All rights reserved.