Synthesis, characterization and crystal structure of a novel binuclear copper(II) complex

The binuclear copper(II) complex [Cu-2(dyma)(2)(phen)(2)] center dot 4H(2)O center dot 2DMF (Na(2)dyma = sodium 2-[1,3]-dithiolan-2-ylidene-malonate, phen = 1,10-phenanthroline) has been synthesized and characterized by analysis, IR and electronic spectroscopy, and variable temperature magnetic susceptibility measurements. A single-crystal X-ray diffraction analysis shows that each copper atom exhibits distorted square-pyramidal coordination geometry, bonded to two oxygen atoms of dyma, two nitrogen atoms of phen and an oxygen atom from a neighbouring molecule, thus forming a binuclear complex. The binuclear units form columns along the b axis via pi-pi interactions between phen ligands. Hydrogen bonds between 1D columns lead to a 2D network. IR and electronic spectra are consistent with the structure. In the temperature range 230-290 K, the complex exhibits weak antiferromagnetic behaviour and, below 230 K, ferromagnetic behaviour.