Quaternary chalcogenides of the IVa metals with layered structures: Preparation and crystal structures of TlCuTIV Q3 (T = Zr, Hf; Q = S, Se) and their relation to the Re3B structure type

Article abstract of DOI:10.1016/S0925-8388(96)02361-4

The new compounds TlCuT^IVQ₃ (T = Zr, Hf; Q = S, Se) were prepared by reacting intimate mixtures of Tl₂S or TlSe with stoichiometric amounts of the corresponding Group IV metal, Cu and the corresponding chalcogen at 870°C. The four compounds are isostructural and crystallize in Cmcm, Z = 4 with a = 3.726(4) A, b = 13.987(9) A, c = 9.783(4) A for TlCuZrS₃; a = 3.847(1) A, b = 14.381(6) A, c = 10.150(1) A for TlCuZrSe₃; a = 3.694(1) A, b = 14.030(3) A, c = 9.750(3) A for TlCuHfS₃; and a = 3.831(1) A, b = 14.409(9) A, c = 10.124(2) A for TlCuHfSe₃. Their crystal structures were determined from single crystal diffractometer data (Mo Kα radiation, ambient temperature) and refined to conventional R values of 0.016, 0.040, 0.019 and 0.031 respectively. An outstanding feature of their crystal structures is the formation of infinite anionic layers, ²_∞-[CuT^IVQ₃]^- parallel to (010), which are separated by Tl⁺ cations. These layers are built up by edge sharing TQ₆ octahedra and distorted CuQ₄ tetrahedra. Average T-Q distances are d(Zr-S) = 2.586(1) A, d(Zr-Se) = 2.707(1) A, d(Hf-S) = 2.569(2) A and d(Hf-Se) = 2.694(1) A. Cu-chalcogen distances are d(Cu-S) = 2.318(2) A and d(Cu-Se) = 2.432(3) A respectively. The thallium ions are in bicapped trigonal prismatic chalcogen coordinations. The atomic arrangement corresponds to that of KCuZrS₃; based on the thallium-chalcogen partial structure it can be regarded as a filled variant of an anti-Re₃B structure type.