Fixation modes of gold(III) from solutions using cadmium(II) dithiocarbamates. Preparation, supramolecular structure and thermal behaviour of polynuclear and heteropolynuclear gold(III) complexes: Bis(N,N-dialkyldithiocarbamato-S,S′)gold(III) polychlorometallates, [Au(S2CNR2)2]nX (n=1: X=[AuCl4]−; n=2: X=[CdCl4]2−, [Cd2Cl6]2−)

• Published in: Polyhedron 2012-06, Vol.40 (1), p.53-64
• Main Authors: Rodina, Tatyana A., Ivanov, Alexander V., Gerasimenko, Andrey V., Loseva, Olga V., Antzutkin, Oleg N., Sergienko, Valentin I.
• Format: Article
• Language: English
• Subjects: 13C CP/MAS NMR spectroscopy; Chemistry of Interfaces; Gränsytors kemi; Heteropolynuclear gold(III)–cadmium(II) complexes; Inorganic four-membered metallocycles; Molecular and supramolecular structures; N,N-Dialkyldithiocarbamate ligands; Polynuclear heteroleptic gold(III) complexes; Thermal behaviour
• ISSN: 0277-5387; 1873-3719
• DOI: 10.1016/j.poly.2012.03.043

We report on a chemisorption activity of four cadmium(II) dialkyldithiocarbamates, [Cd(S2CNR2)2]n R=CH3, C3H7, iso-C3H7 and iso-C4H9, with respect to [AuCl4]− ions in 2M hydrochloric acid. Polynuclear heteroleptic complexes, bis(N,N-dialkyldithiocarmato-S,S′)gold(III) polychlorometallates: [Au(S2CNR2)2]nX (n=1: X=[AuCl4]−, R=iso-C3H7 (3), iso-C4H9 (4); n=2: X=[CdCl4]2−, R=CH3 (1); X=[Cd2Cl6]2−, R=C3H7 (2)) were isolated as the fixation modes of gold(III) and studied using 13C CP/MAS NMR spectroscopy, single-crystal X-ray diffraction and simultaneous thermal analysis (STA). In the cations, the gold atoms S,S′-bidentately coordinate two dialkyldithiocarbamate ligands forming the coordination polygons [AuS4], while in the anions, the central atoms are characterised by the neighbouring environment of four chlorine atoms [MCl4] (M=Cd, Au). The square-planar geometry of both types of Au(III) chromophores reflects a low-spin, intraorbital dsp2 hybrid state of the gold atoms. Unusually complicated supramolecular structural organisations were found for all isolated complexes: (i) binuclear cations, [Au2{S2CN(CH3)2}4]2+, (ii) trinuclear formations, {[Au{S2CN(iso-C3H7)2}2]2[AuCl4]}+, and (iii) polynuclear chains, ([Au(S2CNR2)2]+)n, (R=C3H7 and iso-C4H9), all in combination with (iv) [AuCl4]−, (v) [CdCl4]2− and (vi) [Cd2Cl6]2− ions, are in the structural basis of compounds 1–4. TG and DSC techniques were employed to study thermal behaviour of complexes 1–4 under an argon atmosphere. [Display omitted] ► Polynuclear gold(III) and gold(III)–cadmium complexes comprising dithiocarbamate ligands. ► Supramolecular self-organisation of [Au(S2CNR2)2]nX (n=1, X=[AuCl4]−; n=2, X=[CdCl4]2− and [Cd2Cl6]2−). ► Four-membered chelate rings [AuS2C] and the planar [AuS4] and [AuCl4] chromophores. ► Thermal decomposition of the complexes yields reduced metallic gold as the final product. Four novel heteropolynuclear and polynuclear complexes of the general formulae [Au(S2CNR2)2]2X (X=[CdCl4]2−, R=CH3 (1); X=[Cd2Cl6]2−, R=C3H7 (2)) and [Au(S2CNR2)2][AuCl4] (R=iso-C3H7 (3); R=iso-C4H9 (4)) were prepared using heterogeneous reactions between appropriate freshly precipitated binuclear cadmium(II) dialkyldithiocarbamates and AuCl3 in 2M hydrochloric acid. The isolated complexes were studied by 13C CP/MAS NMR spectroscopy, single-crystal X-ray diffraction and simultaneous thermal analysis (STA) under an argon atmosphere. In all molecular structures (1–4), one of the gold atoms coordinates two