Crystal polymorphism of the double pseudopolymeric gold(III)-thallium(III) dithiocarbamato-chlorido complex of [Au(SCNPr)][TlCl]: preparation, self-assembly of supramolecular architectures, and thermal behavior

The interaction of thallium(I) N,N-dipropyldithiocarbamate with [AuCl] anions in a 2M HCl medium was studied. The heterogeneous reaction of gold(III) binding from solution to the solid phase, including the redox process, results in the formation of a double dithiocarbamato-chlorido complex of [Au(SCNPr)][TlCl]. The crystals of the obtained compound are characterized by their ability to polymorphism: at 220 K the complex exists in the form of the α-modification (α-I), while at 296 K the β-modification (β-I) is stable. The α-I/β-I structures include 4/2 nonequivalent square-planar cations of [Au(SCNPr)] (A, 2 B, C/A, B) and 2/1 distorted tetrahedral anions [TlCl]. Self-assembly of these structural units, which are combined due to interionic secondary interactions (the most important of which are chalcogen bonds S···Cl), leads to the formation of the complicated supramolecular architectures such as cation-anionic pseudo-polymeric ribbons. Alternating along the edges of these ribbons and acting as double linkers, thallium(III) anions pairwise combine neighboring iso- meric complex cations of [Au(SCNPr)], which are localized in the central part of the ribbons. When studying the thermal behavior of the complex, TlCl and elemental gold were identified as individual thermolysis products, which are quantitatively reduced and crystallized under low-temperature conditions (up to 300°C).