Syntheses, supramolecular structures, and thermal behavior of heteronuclear gold(III)–mercury(II) dithiocarbamatochloride complexes [Au{S2CN(CH3)2}2]2[HgCl4] and ([Au{S2CN(C2H5)2}2]2[Hg2Cl6] · OC(CH3)2) n by 13C MAS NMR, X-ray diffraction, and simultaneous thermal analysis data

Abstract

New heteronuclear gold(III)–mercury(II) compounds are synthesized by the chemisorption reaction of freshly precipitated mercury dimethyl (MeDtc) and diethyl dithiocarbamates (EtDtc) with [AuCl4]− anions in a medium of 2 M HCl. The crystals of complexes [Au{S2CN(CH3)2}2]2[HgCl4] (I) and ([Au{S2CN(C2H5)2}2]2[Hg2Cl6] • OC(CH3)2)n (II) are obtained from solutions in methanol and acetone, respectively. The crystal and supramolecular structures of the preparatively isolated compounds are determined by X-ray diffraction analysis (CIF files CCDC nos. 1452118 (I) and 1452119 (II)). The structure of ionic complex I is built of alternating binuclear [Au2{S2CN(CH3)2}4]2+ cations and [HgCl4]2− anions. A more complicated structure of compound II contains centrosymmetric isomeric [Au{S2CN(C2H5)2}2]+ cations (A and B) and centrosymmetric binuclear [Hg2Cl6]2− anions. The supramolecular structure of compound II is formed due to pairs of Au•••S secondary bonds between the adjacent gold(III) complex cations resulting in the formation of linear polymeric chains [•••A•••B•••]n (directed along the x crystallographic axis). Isomeric cations A and B are alternated along the chains. The character of thermolysis of the complexes is studied and the regeneration conditions of bound gold are revealed by the simultaneous thermal analysis data. The thermal destruction of compounds I and II occurs simultaneously at the cationic and anionic moieties of the compounds to reduce gold(III) accompanied by the release and subsequent sublimation of mercury(II) chloride. The final product of the thermal transformations of the complexes is reduced elemental gold.