Zn(II), Cd(II) and Hg(II) complexes with 2,2′-biquinoline, syntheses and X-ray crystal structures of [Hg(bq)(SCN)2]

Reaction of the ligand 2,2'-biquinoline (bq) with Zn(ClO4)(2), CdCl2 and Hg(SCN)(2) gives complexes [Zn(bq)(2)] (ClO4)(2), [Cd(bq)(2)Cl-2] and [Hg(bq)(SCN)(2)] which were characterized by elemental analyses and IR spectroscopy. The crystal structure of [Hg(bq)(SCN)(2)] was determined by X-ray crystallography. The complex comprises a monomeric Hg(SCN)2 unit with one 2,2'-biquinoline (bq) ligand coordinated to the Hg atom via the two quinolinic nitrogens, giving rise to a five-membered chelate ring in a distorted tetrahedral environment. A pi-pi stacking interaction exists between the parallel aromatic rings in adjacent chains, resulting in a planar species in which the mean molecular planes are close to parallel and separated by a distance of similar to3.5 Angstrom, close to that of the planes in graphite.