Ternäre Thalliumchalkogenide mit Tl4Ge2S6-Struktur

The new ternary thallium chalcogenides Tl₄Si₂S₆, Tl₄Si₂Se₆, and Tl₄Ge₂Se₆ were synthetized from the elements. The compounds crystallize in the triclinic system (space group P) with the cell parametersa=6.699 (5),b=6.645 (4),c=8.380 (5) Å, =90.32 (5), =112.00 (5), =112.32 (5)° for Tl₄Si₂S₆,a=6.875 (2),b=6.866 (2),c=8.731 (2) Å, =90.50 (2), =111.69 (2), =113.70 (2)° for Tl₄Si₂Se₆,a=6.925 (6),b=6.934 (7),c=8.771 (6) Å, =90.55 (7), =111.42 (6), =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 Tl₄Ge₂S₆¹. 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.