A fixation mode of gold from solutions using heterogeneous reaction of cadmium dicyclohexyl dithiophosphate with H[AuCl4]. Structural and (13C, 31P) CP/MAS NMR studies and thermal behaviour of crystalline polymeric gold(I) dicyclohexyl dithiophosphate and bis(dicyclohexylthiophosphoryl) disulphide

Two novel compounds: polynuclear catena-poly[bis(mu(3)-O,O'-di-cyclo-hexyldithiophosphato-S,S,S') digold(I)] (Au-Au) (1) and crystalline bis(O,O'-di-cyclo-hexylthiophosphoryl)disulphide, (cyclo-C6H11O)(2)-P(S)S-S(S)P(O-cyclo-C6H11)(2) (2) were prepared using heterogeneous reaction between freshly precipitated binuclear cadmium(II) dithiophosphate (Dtph), [Cd-2{S2P(O-cyclo-C6H11}O-4] and H[AuCl4] in 2 M hydrochloric acid. The isolated compounds 1 and 2 (the fixation mode of gold from the solution and the oxidised form of Dtph groups, respectively) have been studied by means of single-crystal X-ray diffraction, C-13 and P-31 cross-polarisation/magic-angle-spinning (CP/MAS) NMR spectroscopy and simultaneous thermal analysis (STA). Centrosymmetric binuclear molecule of 1, [Au-2{S2P(O-cydo-C6H11)(2)}(2)] comprises a pair of mu-bridging di-cyclo-hexyl Dtph ligands, linking two neighbouring gold atoms, and displays additional intramolecular aurophilic bond Au center dot center dot center dot Au. At the supramolecular level of structural self-organisation of complex 1, infinite polymeric zigzag chains arise due to pairs of the secondary bonds Au center dot center dot center dot S between neighbouring binuclear molecules. Centrosymmetric molecule of 2 displays two O,O'-di-cydo-hexythiophosphoryl fragments, which are connected by the chemical bond S(1)-S(1)(a), and a planar zigzag array [S=P-S-S-P=S] passing through the central part of the molecule. To characterise additionally the Dtph groups in both compounds 1 and 2, chemical shift anisotropy (CSA) parameters (delta(aniso) and eta) were calculated from spinning sideband manifolds in experimental P-31 MAS NMR spectra. The thermal behaviour of complex 1 was studied using simultaneous thermal analysis (a combination of TG and DSC) under an argon atmosphere. The thermal behaviour displays stepwise mass loss, comprising thermal decompositions of the organic and inorganic parts of I with gold(l) dithio-meta-phosphate and reduced metallic gold as the intermediate and the final products, respectively. (C) 2012 Elsevier B.V. All rights reserved.