Copper(II) complexes of new unsymmetrical NSN thioether ligands

The reactions of 2-(mercaptoethyl)benzimidazole with 2-vinylpyridine and 2- picolyl chloride (in basic medium) yield the new unsymmetrical ligands 1-(2 -benzimidazolyl)-5-(2'-pyridyl)-3-thiapentane (Biptp) and 1-(2-benzimidazol yl)-4-(2'-pyridyl)-3-thiabutane (Biptb), respectively. Copper(II) complexes of these ligands with differing anions were prepared. Crystal structures a re reported for [Cu(Biptp)](CF3SO3)(2). 2H,O and [Cu(Biptb)](CF3SO3)(2).0.5 (C7H8).H2O, in which the Cu(II) ions exhibit distorted square-pyramidal geo metries. Powder ESR spectra of the copper compounds are rhombic and the deg ree of rhombicity is related to the identity of the anions. Charge-transfer bands and intense absorption in the visible region are observed in the ele ctronic spectra. Electrochemical studies indicate that one-electron reducti ons are involved, the reductions occurring at relatively high potentials. ( C) 2001 Elsevier Science B.V. All rights reserved.