Structural Characterization and EPR Spectral Studies on Mononuclear Copper(II) Complex of Saccharin with Ethylnicotinate

Abstract

Mononuclear copper(II) saccharinate (sac) complex containing ethylnicotinate (enc), [Cu(enc)<inf>2</inf>(sac)<inf>2</inf>(H<inf>2</inf>O)]·1.4H<inf>2</inf>O has been synthesized and characterized by spectroscopic (IR, UV-vis, EPR), X-ray diffraction technique and electrochemical methods. It crystallizes in the tetragonal crystal systems with space group I4<inf>1</inf>cd and Z = 8. The copper(II) ion presents a CuN<inf>4</inf>O distorted square pyramidal coordination. 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 DMF (110 K), indicate the presence of the unpaired electron in the d<inf>x2 - y2</inf> orbital. The evaluated metal-ligand bonding parameters showed strong in-plane σ and in-plane π-bonding. Some comparisons with related structures are made and the most important features of its IR spectrum were also discussed. The cyclic voltammogram of the title complex investigated in DMF (dimethylformamide) solution exhibits only metal centred electroactivity in the potential range ±1.25 V vs. Ag/AgCl reference electrode. © 2008 Elsevier B.V. All rights reserved.