Synthesis and crystal structure of a group of phenoxo-bridged heterodinuclear [NiIIHgII] Schiff base complexes

Four new heterodinuclear complexes of a group of the general formula, [NiHg(L)Cl-2] where the Schiff base anion, L = 2,2'-[propane-1,2-diylbis(nitrilomethylylidene)] diphenolate (L-1), (1); 2,2'-[propane-1,2-diylbis(nitriloeth-1-yl-1-ylidene)] diphenolate (L-2), (2); 2,2'-[propane-1,2-diylbis(nitriloprop-1-yl-1-ylidene)] diphenolate (L-3), (3) and 2,2'-[propane-1,3-diylbis(nitrilomethylylidene)] diphenolate (L-4), (4) have been prepared. The syntheses have been achieved by reacting equimolar amounts of nickel perchlorate, mercuric chloride and the respective tetradentate Schiff base ligand (H2L) in methanol medium. The complexes have been characterized by microanalytical, spectroscopic, single crystal X-ray diffraction and other physicochemical studies. Structural studies on 1-4 reveal the presence of a heterodinuclear [(NiHgII)-Hg-II] unit in which the central Ni(II) and Hg(II) ions are connected to each other by two phenolate oxygen bridges. In each of the complexes, the Ni(II) ion adopts a distorted square planar (NiO2N2) geometry while the Hg(II) ion assumes a distorted tetrahedral arrangement (HgO2Cl2). The dinuclear units in 1-4 are self-assembled through weak intermolecular pi center dot center dot center dot interactions to build up supramolecular network in their solid state. (c) 2012 Elsevier Ltd. All rights reserved.