Syntheses and characterization of some homoleptic (1,1-dithiolato)copper(II) and nickel(II) complexes, and mixed-ligand (1,1-dithiolato)nickel(II) chelates containing nitrogenous bases. Crystal structures of tetrabutylammonium(1-cyano-1-chlorophenyl-2,2-ethylenedithiolato)copper(II), [(2,2′-bipyridine)(1-cyano-1-phenyl-2,2-ethylenedithiolato)nickel(II)], and 5-amino-4-(4-chlorophenyl)-[1,2]dithiole-3-thione

Abstract

A series of divalent nickel and copper complexes and a series of mixed-ligand nickel(II) chelates have been prepared and characterized. The general formula of the complexes is [cation] 2[M(1,1-dithiolate) 2] (M = Ni(II), Cu(II)), and that of the mixed-ligand is [Ni(enR)(SS)], containing the dianion of 1,1-dithiolate derivatives and an N-alkyl- or N-phenyl-substituted 1,2-diaminoethane or a bidentate nitrogenous base, enR. The structures of the complexes, both in the solid state and in solution, have been determined by IR, UV-Vis, room temperature magnetic and electrical conductance measurements. The MS 4 chromophoric group is common to all of the homoleptic complexes and contains two four-membered chelate rings. The MS 2N 2 chromophoric group is common to the mixed-ligand complexes. The 1,1-dithiolate derivatives are substituted isomaleonitriles of the formula Y ( CN ) C CS 2 2 - , where Y = CONH 2 (1-cyano-1-carboamido-2,2-ethylenedithiolate, CCED); COOEt (1-cyano-1-carboethoxy-2,2-ethylenedithiolate, CED); ph (1-cyano-1-phenyl-2,2-ethylenedithiolato, CPD) and Cl-ph (1-cyano-1-chlorophenyl-2,2-ethylenedithiolate, CCPD). X-ray structural analyses were performed for three compounds. The tetrabutylammonium(1-cyano-1-chlorophenyl-2,2-ethylenedithiolato)copper(II) complex consists of three molecules per unit cell. The copper atom lies on a crystallographic center of symmetry which requires the CuS 4 unit to be planar. The average Cu–S bond length is 2.204 Å. In the unit cell of the complex [(2,2′-bipyridine)(1-cyano-1-phenyl-2,2-ethylenedithiolato)nickel(II)] there are six nickel atoms. In the immediate vicinity of each nickel atom exist two sulfur and, at a shorter distance, two nitrogen atoms. The molecules in the unit cell are arranged in pairs, each pair forming two weak intermolecular Ni⋯S bond interactions at a distance of 3.617 Å. In the novel sulfur-rich ligand 5-amino-4-(4-chlorophenyl)-[1,2]dithiole-3-thione, three carbon atoms are linked with two sulfur atoms forming a five-membered ring. All observed intramolecular bond lengths in the sulfur ring indicate delocalization of the π-electron system.