Preparation, crystal structures and spectroscopic characterization of oxalate copper(II) complexes containing the nitrogen ligands 4,4′-dimethyl-2,2′-bipyridine and di(2-pyridyl)sulfide

Abstract

The preparation, crystal structures and spectroscopic characterization of four oxalate copper(II) complexes containing the 4,4′-dimethyl-2,2′-bipyridine (Mebpy) or di(2-pyridyl)sulfide (DPS) nitrogen ligands namely [μ-(ox){Cu(Mebpy)(NO 3)(H 2O)} 2] ( 1), [μ-(ox){Cu(Mebpy)(ClO 4)(H 2O)} 2] ( 2), [μ-(ox){Cu(DPS)(H 2O)} 2](ClO 4) 2 ( 3) and [Cu(DPS)(ox)(H 2O)] · 2H 2O ( 4) are described. X-ray diffraction measurements have shown that complexes 1– 3 are binuclear, in which the oxalate anion bridges two Cu(II) centers, while the complex ( 4) is mononuclear and the oxalate anion adopts the terminal bidentate chelating coordination mode. In 1 and 2 the Cu(II) sites display a distorted octahedral geometry (4+2 environment) and in compounds 3 and 4 the Cu(II) centers exhibit a slightly distorted square pyramidal geometry. In addition, complexes 1 and 2 present a 2D supramolecular arrangement through hydrogen bonds between coordination water molecules and nitrate or perchlorate anions and π-stacking interaction between the pyridyl rings of Mebpy nitrogen ligands.