Cobalt(II), Zinc(II) and Cadmium(II)-Squarate Complexes With N-Methylimidazole

Abstract

Three M(II)-squarate complexes, [Co(sq)(H <inf>2</inf>O)(Nmim) <inf>4</inf>] (1), [Zn(μ <inf>1,3-</inf>sq)(H <inf>2</inf>O) <inf>2</inf> (Nmim) <inf>2</inf>] <inf>n</inf> (2) and [Cd(μ <inf>1,3-</inf>sq)(H <inf>2</inf>O) <inf>2</inf>(Nmim) <inf>2</inf> ] <inf>n</inf> (3) (sq = squarate, Nmim = N-methylimidazole) have been synthesized and characterized by elemental, spectral (IR and UV-Vis.) and thermal analyses. The molecular structures of the complexes have been investigated by single crystal X-ray diffraction technique. The squarate ligand acts as two different coordination modes as a monodentate (in 1) and bis(monodentate) (O 1-O 3) bridging ligand (in 2, 3). The Co(II) atom has a distorted octahedral geometry with the basal plane comprised of three nitrogen atoms of Nmim ligands and a oxygen atom of squarate ligand. The axial position is occupied by a nitrogen atom of Nmim and one aqua ligand. The crystallographic analysis reveals that the crystal structures of 2 and 3 are one-dimensional linear chain polymers along the c and b axis, respectively. The configuration around each metal(II) ions are distorted octahedral geometry with two nitrogen atoms of trans-Nmim, two aqua ligands and two oxygen atoms of squarate-O 1,O 3 ligand. These chains are held together by the C-H···π, π···π and hydrogen-bonding interactions, forming three-dimensional network. © 2010 Springer Science+Business Media, LLC.