Interaction of binuclear zinc diethyldithiocarbamate with H[AuCl4]/2 M HCl: The preparation, supramolecular self-organization, and thermal behavior of the heteropolynuclear complex ([Au{S2CN(C2H5)2}2]2[ZnCl4] · 1/2CO(CH3)2 · 1/2CHCl3) n

Abstract

The interaction of the freshly precipitated binuclear zinc diethyldithiocarbamate (EDtc) [Zn2{S2CN(C2H5)2}4] with a solution of AuCl3 in 2 M HCl was studied. A water-soluble gold(III)-zinc complex was formed as a result of this interaction; it was preparatively isolated as the solvated polymeric species ([Au{S2CN(C2H5)2}2]2[ZnCl4] · 1/2CO(CH3)2 · 1/2CHCl3) n (I). According to single-crystal X-ray diffraction (XRD) analysis data, the resulting compound includes four structurally nonequivalent complex cations [Au{S2CN(C2H5)2}2]+ (with Au(1), Au(2), Au(3), and Au(4) atoms, A-D, respectively) and two [ZnCl4]2− anions (E = Zn(1), F = Zn(2)), which are related to each other as conformers. At the supramolecular level, isomeric cations are characterized by a complex structural ordering mode: complex cations B, C, and D form polymeric chains like (⋯B[⋯A]⋯ D⋯C⋯) n oriented along the crystallographic a axis, in which cation A serves as a side substituent, due to secondary Au⋯S bonds and short contacts between the nearest neighbors. Outer-sphere solvating molecules and isomeric distorted tetrahedral [ZnCl4]2− anions linked to [Au{S2CN(C2H5)2}2]+ cations by secondary Cl⋯S bonds are localized between the chains. The thermal behavior of compound I was studied by simultaneous thermal analysis. The multistage process of thermal decomposition includes the desolvation of the complex and the thermolysis of its dithiocarbamate moiety and [ZnCl4]2− with the release of gold metal and zinc chloride and the partial formation of ZnS. The final products of these thermal transformations are reduced gold and ZnS.