Crystal Polymorphism of the Pseudopolymeric Double Gold(III)–Thallium(III) Dithiocarbamato–Chlorido Complex [Au(S2CNPr2)2][TlCl4]: Preparation, Self-Assembly of Supramolecular Architectures, and Thermal Behavior

The interaction of thallium(I) N,N-dipropyldithiocarbamate with [AuCl₄]^– anions in a 2 M HCl medium has been studied. The heterogeneous reaction of gold(III) binding from solution to the solid phase, involving a redox process, results in the formation of the double dithiocarbamato–chlorido complex [Au(S₂CNPr₂)₂][TlCl₄]. The crystals of this compound are prone 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 [Au(S₂CNPr₂)₂]⁺ cations (A, 2 B, C/A, B) and 2/1 distorted tetrahedral [TlCl₄]^– anions. 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 complicated supramolecular architectures such as pseudopolymeric cation–anion ribbons. Alternating along the edges of these ribbons and acting as double linkers, thallium(III) anions pairwise combine neighboring isomeric [Au(S₂CNPr₂)₂]⁺cations located in the central part of the ribbons. Studying the thermal behavior of the complex, it was demonstrated that individual thermolysis products are TlCl and elemental gold, which is quantitatively reduced and crystallized under low-temperature conditions (up to 300°C).