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
O. V. Loseva1, T. A. Rodina2, A. I. Smolentsev3, A. V. Ivanov1
1Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences, Blagoveshchensk, Russia
2Amur State University, Blagoveshchensk, Russia
3Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: zinc dialkyldithiocarbamates with chemisorption properties, forms of gold binding from solutions, heteropolynuclear gold(III)-zinc complexes, crystal and supramolecular structure, X-ray crystallography, 13C MAS NMR, simultaneous thermal analysis
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 non-centrosymmetric 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.
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