Gold(III) ionic complexes [Au{S2CN(C2H5)2}2]Cl and ([Au{S2CN(C2H5)2}2][AuCl4]) n : Synthesis, supramolecular self-assembly, polymorphism, and thermal behavior

Abstract

A heterogeneous reaction between freshly precipitated oxovanadium(IV) diethyldithiocarbamate [VO{S2CN(C2H5)2}2] and a solution of AuCl3 in 2 M HCl has been shown to yield two ionic gold(III) compounds: the water-soluble ionic complex [Au{S2CN(C2H5)2}2]Cl (I) and the coordination polymer ([Au{S2CN(C2H5)2}2][AuCl4])n (II), which was preparatively separated from the precipitate phase. The molecular and crystal structures of the synthesized complexes have been established by X-ray diffraction. The crucial role in the supramolecular self-assembly of the compounds obtained belongs to C-H⋯Cl hydrogen bonds (in I) and Au⋯S and Au⋯Cl secondary interactions (in II). Polymeric complex II has been found to be able to form two polymorphs, which differ from each other by the building mode of cation-anion polymeric chains. The study of the thermal behavior of the synthesized complexes by simultaneous thermal analysis in an argon atmosphere has allowed us to recognize conditions for the recovery of bound gold. In both cases, reduced metallic gold is the only final thermolysis product.