Species of Gold(III) Binding by Binuclear Zinc Dipropyldithiocarbamate: Supramolecular Self-Organization and Thermal Behavior of Ionic Complexes [Au(S2CNPr2)2]2[ZnCl4] and [Au(S2CNPr2)2]2[AuCl4][AuCl2]

Abstract

The reaction of binuclear zinc dipropyldithiocarbamate [Zn2{S2CN(C3H7)2}4] with an AuCl3/2 М HCl solution is studied. The double ionic complex [Au{S2CN(C3H7)2}2]2[ZnCl4] (I) is identified as the main species of gold(III) binding in the heterogeneous system under study and is characterized by 13С and 15N CP-MAS NMR spectroscopy. Single crystals of heterovalent compound [Au{S2CN(C3H7)2}2]2[AuCl4][AuCl2] (II) are sampled as a by-product. The crystal and supramolecular structures of complexes I and II are determined by the direct XRD method (CIF files CCDC nos. 2159171 and 2159170, respectively). The self-organization of the complex pseudopolymeric structures of compounds I and II are shown to be due to the binding of ionic structural units by secondary nonvalent interactions Au⋅⋅⋅S and S⋅⋅⋅Cl and hydrogen bonds C–H⋅⋅⋅Cl. The thermal behavior of the complexes is studied by simultaneous thermal analysis (STA), and the quantitative regeneration of bound gold (I and II) with the partial transformation of released ZnCl2 to ZnS (I) is found.