Ein Orthoperrhenat mit flächenverknüpften ReO6-Oktaedern: Hochdrucksynthese und Kristallstruktur von K3NaRe2O9 / An Orthoperrhenate with Face-Sharing ReO6 Octahedra: High-Pressure Synthesis and Crystal Structure of K3NaRe2O9
AbstractThe title compound was prepared by high-pressure reaction of rhenium metal with technical grade (i.e., Na containing) KO2 in a modified Belt-type apparatus (20 kbar, 1000 °C, 60 min, Au capsule). The amber-coloured crystals are very hygroscopic and decompose rapidly when exposed to air. K3NaRe2O9 crystallizes hexagonally, space group P63/mmc, with a = 6.012(1), c = 14.342(14) Å, c/a = 2.386 and Z = 2. The structure was refined to R = 0.031, Rw = 0.023 for 422 independent, absorption-corrected reflections with l > σ (I). K3NaRe2O9 is isostructural with 6H-BaTiO3, a perowskite variant, and contains Na and Re in octaedral coordination. Two ReO6 octahedra are face-sharing, thus creating a Re2O9 double octahedron with a Re-R e distance of 2.92 Å.