(Na-15-Krone-5)₂ReCl₆·4 CH₂Cl₂, eine Struktur mit CH₂Cl₂-Molekülen in pseudohexagonalen Kanälen

Abstract

The monoclinic crystal structure of (Na-15-crown-5)₂ReCl₆·4 CH₂Cl₂ was determined by X-ray diffraction (P2₁/c, Z = 4, R₁ = 0.061). It contains octahedral ReCl₆^2- ions that are joined on two opposite octahedron faces to two Na⁺ ions; each Na⁺ is coordinated with one crown ether molecule. One of the crown ether molecules is disordered in two orientations. The resulting ‘Kro-Re-Kro’ units have a nearly cylindrical shape and are stacked to rods that run parallel to c. The rods form a pseudohexagonal rod packing in which one third of the rods is missing. The channels in the places of the missing rods are filled with solvent molecules showing high thermal motion. Another description is that of a hexagonal-closest packing of Kro-Re-Kro units, the channels resulting from the strings of face-sharing octahedral voids of the packing. Group–subgroup relations show that the deviation of the Kro-Re-Kro packing from hexagonal symmetry is astonishingly small. The crystal structure of ‘(P(C₆H₅)₄)₂ReCl₆·2 CH₃CN’ is confirmed; however, the chemical formula must be corrected, it is (P(C₆H₅)₄)₂ReCl₆·4 CH₃CN).