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(HFCL6)

Selenium, SeCl4, and MCl(4) (M = Zr, Hf) react in a sealed evacuated glass ampoule at 130 degrees C to afford red, moisture sensitive crystals of Se-4(2+)(ZrCl62-) and Se-4(2+)(HfCl62-). The isotypic crystal structures (tetragonal, P4(2)/ncm, Z = 4) consist of square-planar Se-4(2+) cations and slightly distorted octahedral MCl(6)(2-) (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, TeCl4, and HfCl4 one obtains under similar conditions at 200 degrees C Te-4(2+)(HfCl62-) in form of dark violet crystals. The crystal structure (triclinic, P (1) over bar, Z = 1) built of nearly square-planar Te-4(2+) ions and octahedral HfCl62- ions. The packing of the ions corresponds to a rhombohedrally distorted CsCl structure type.