Ternäre Thalliumchalkogenide mit Tl₄Ge₂S₆-Struktur

Abstract

The new ternary thallium chalcogenides Tl₄Si₂S₆, Tl₄Si₂Se₆, and Tl₄Ge₂Se₆ were synthetized from the elements. The compounds crystallize in the triclinic system (space group P$\bar 1$) with the cell parametersa=6.699 (5),b=6.645 (4),c=8.380 (5) Å, α=90.32 (5), β=112.00 (5), γ=112.32 (5)° for Tl₄Si₂S₆,a=6.875 (2),b=6.866 (2),c=8.731 (2) Å, α=90.50 (2), β=111.69 (2), γ=113.70 (2)° for Tl₄Si₂Se₆,a=6.925 (6),b=6.934 (7),c=8.771 (6) Å, α=90.55 (7), β=111.42 (6), γ=114.45 (7) for Tl₄Ge₂Se₆ andZ=1 for all cases. On the basis of single crystal X-ray intensity data the compounds were shown to be isostructural with Tl₄Ge₂S ¹₆ . The crystal structures of Tl₄Si₂S₆, Tl₄Si₂Se₆, and Tl₄Ge₂Se₆ are characterized by anions [Si₂S₆]⁴⁻, [Si₂Se₆]⁴⁻, and [Ge₂Se₆]⁴⁻ which consist of two tetrahedral SiS₄, SiSe₄, and GeSe₄ groups, respectively, with a common edge. A short comparative discussion of dinuclear tetrahedral thio- and selenoanions of main group elements is given.