Chalcogen Polycations with Mononuclear Divalent Anions from Chalcogen Subhalides and Tetrachlorides of Zr and Hf: Syntheses and Crystal Structures of Se 4 (MCl 6 ) (M = Zr, Hf) and Te 4 (HfCl 6 )

Selenium, SeCl 4 , and MCl 4 (M = Zr, Hf) react in a sealed evacuated glass ampoule at 130°C to afford red, moisture sensitive crystals of Se 2+ 4 (ZrCl 2‐ 6 ) and Se 2‐ 6 (HfCl 2‐ 6 ). The isotypic crystal structures (tetragonal, P 4 2 / ncm, Z = 4) consist of square‐planar Se 2+ 4 cations and slightly distorted octahedral MCl 2‐ 6 (M = Zr, Hf) anions. The ions are packed corresponding to the NaCl structure type with the centres of gravity of the Se 4 rings and the metal atoms of the MCl 6 octahedra in the Na and Cl positions. From Te, TeCl 4 , and HfCl 4 one obtains under similar conditions at 200°C Te 2+ 4 (HfCl 2‐ 6 ) in form of dark violet crystals. The crystal structure (triclinic, P 1, Z = 1) is built of nearly square‐planar Te 2+ 4 ions and octahedral HfCl 2‐ 6 ions. The packing of the ions corresponds to a rhombohedrally distorted CsCl structure type.