Chemisorption Synthesis of the Ion-Polymeric Heteronuclear Gold(III)–Bismuth(III) Complex ([Au{S₂CN(C₃H₇)₂}₂]₃[Bi₂Cl₉])_n Based on [Bi₂{S₂CN(C₃H₇)₂}₆]: ¹³C MAS NMR, Supramolecular Structure, and Thermal Behavior

Chemisorption synthesis on the basis of the binuclear compound [Bi₂{S₂CN(C₃H₇)₂}₆] (I) and preparative isolation of the ion-polymeric heteronuclear gold(III)–bismuth(III) complex ([Au{S₂CN(C₃H₇)₂}₂]₃[Bi₂Cl₉])_n (II) are carried out. Compounds I and II are characterized in comparison by IR spectroscopy and ¹³C CP-MAS NMR. According to the X-ray diffraction analysis data (CIF file CCDC no. 1407705), the cationic moiety of compound II exhibits an unusually complicated supramolecular structure including six isomeric noncentrosymmetric complex cations [Au{S₂CN(C₃H₇)₂}₂]⁺ (hereinafter A–F) and two binuclear anions [Bi₂Cl₉]^3– as conformers. The isomeric gold(III) cations perform various structural functions. Owing to pair secondary interactions Au···S, cations B, C, E, and F form centrosymmetric ([E···E], [F···F]) and noncentrosymmetric ([B···C]) binuclear aggregates [Au₂{S₂CN(C₃H₇)₂}₄]²⁺, whereas cations A and D are not involved in dimerization. The strongest secondary Au···S bonds are formed between the binuclear and mononuclear cations, resulting in the formation of supramolecular cation-cationic polymer chains of two types: (⋅⋅⋅A⋅⋅⋅[B⋅⋅⋅C]⋅⋅⋅A⋅⋅⋅[B⋅⋅⋅C]⋅⋅⋅)_n and (D⋅⋅⋅[E⋅⋅⋅E]⋅⋅⋅D⋅⋅⋅[F⋅⋅⋅F]⋅⋅⋅])_n. In both chains, the gold atoms of the binuclear cations are characterized by a distorted octahedral coordination [S₆], whereas in the mononuclear cations the gold atoms retain the square environment [S₄]. The cation-anionic interactions are provided by secondary bonds Cl⋅⋅⋅S involving the terminal chlorine atoms of isomeric [Bi₂Cl₉]^3– and the sulfur atoms of the binuclear cations [Au₂{S₂CN(C₃H₇)₂}₄]²⁺. The character of the thermal behavior of compounds I and II is studied by simultaneous thermal analysis with the identification of intermediate and final products of the thermal transformations. The thermolysis of compound I at 193–320°C is accompanied by the formation of Bi₂S₃ with an impurity of reduced metallic bismuth particles. The final products of the thermal transformations of compound II are reduced elemental gold and Bi₂O₃, and the thermal transformation intermediates are BiCl₃ and Bi₂S₃.