Synthesis, supramolecular self-organization, and thermal behavior of the heteropolynuclear complex ([H3O][Au{S2CN(CH2)6}2][Au2{S2CN(CH2)6}4][ZnCl4]2) n

Abstract

The interaction of binuclear zinc cyclo-hexamethylenedithiocarbamate [Zn2{S2CN(CH2)6}4] with [AuCl4]− anions in the 2M HCl medium is studied. The result of a heterogeneous reaction involving the chemisorption binding of gold(III) from a solution and partial ion exchange, was the formation of a heteropolynuclear gold(III)-zinc complex as an individual form of gold(III) binding. The crystal and molecular structure of the polymeric complex of the composition ([H3O][Au{S2CN(CH2)6}2][Au2{S2CN(CH2)6}4][ZnCl4]2)n (I) is determined by single crystal X-ray diffraction. The structure of the complex contains three isomeric complex [Au{S2CN(CH2)6}2]+ cations: centrosymmetric A with the Au(1) atom and two non-centrosymmetric B with Au(2) and C with Au(3). Due to the pairs of non-symmetric secondary Au⋯S interactions of the non-valence type, the noncentrosymmetric cations form a binuclear [Au2{S2CN(CH2)6}4]2+ cation of the B⋯C type. The subsequent structural self-organization of the complex at the supramolecular level also proceeds due to Au⋯S interactions between the binuclear B⋯C and mononuclear A cations, as a result of which zigzag polymeric chains (⋯ [B⋯C]⋯A⋯)n are formed. The hydronium ion participates in the pairwise binding of [ZnCl4]2− anions by Cl⋯O hydrogen bonds. The multistage process of the thermal destruction of I includes the dehydration of the complex, thermolysis of the dithiocarbamate moiety and [ZnCl4]2− (with releasing metallic gold, ZnCl2, and partial formation of ZnS). The final products of thermal transformations are metallic gold and ZnS.