Cs10Tl6SiO4, Cs10Tl6GeO4, and Cs10Tl6SnO3 – First Oxotetrelate Thallides, Double Salts Containing “Hypoelectronic” [Tl6]6– Clusters


  • Dedicated to Professor Wolfgang Kaim on the Occasion of His 60th Birthday


Cs10Tl6TtO4 (Tt = Si, Ge) and Cs10Tl6SnO3 were synthesized by the reaction of appropriate starting materials at 623–673 K, followed by fast cooling or quenching to room temperature, in arc-welded tantalum ampoules. According to single-crystal X-ray analyses, the compounds crystallize in new structure types (Cs10Tl6TtO4 (Tt = Si, Ge), P21/c and Cs10Tl6SnO3, Pnma), consisting of [Tl6]6– clusters, which can be characterized as distorted octahedra compressed along one of the fourfold axes of an originally unperturbed octahedron, and [SiO4]4–, [GeO4]4– or [SnO3]4– anions. The oxotetrelate thallides can be regarded as “double salts”, which consist of Cs6Tl6 on one side and respective oxosilicates, -germanates and -stannates on the other, showing almost not any direct interaction between the two anionic moieties, as might be expressed e.g. by the formula [Cs6Tl6][Cs4SiO4]. In contrast to the silicon and germanium compounds, where the oxidation state of the tetrel atom is unambiguously 4+, for the threefold coordinated tin atom in Cs10Tl6SnO3 an oxidation state of 2+ has to be assumed. Thus, the latter reveal further evidence that the so called “hypoelectronic” [Tl6]6– cluster does not require additional electrons and is intrinsically stable. The distortion of [Tl6]6– can be understood in terms of the Jahn–Teller theorem. According to magnetic measurements all title compounds are diamagnetic.