TL2PT5S6 - A NEW THIOPLATINATE WITH A CHANNEL-TYPE STRUCTURE

Tl2Pt5S6 was prepared by fusion of Tl2S, Pt and S. The crystal structure was determined from diffractometer data and refined to a conventional R value of 0.037 (772 observations, 64 refined parameters). Tl2Pt5S6 is monoclinic, mP26, space group P2(1)/n, with a=6.971(1) angstrom, b=6.941(1) angstrom, c=11.088(2) angstrom, beta=97.83(2)-degrees and Z=2. It crystallizes with a new structure type, characterized by a three-dimensional Pt-S framework consisting of infinity2-Pt4S6 layers linked together by additional Pt atoms. Large channels crossing each other in the [100] and [010] directions host the thallium atoms. Pt atoms are in distorted square planar sulphur coordinations typical of Pt(II) (d(Pt-S)=2.29-2.38 angstrom). Tl is characterized by a very polar coordination, indicative of a pronounced stereochemical activity of the lone pair. It is surrounded by three close sulphur neighbours (d(Tl-S)=3.037-3.301 angstrom) in a PSI-tetrahedral configuration.