| | Abstract
| The title com pound was prepared by high-pres sure reaction of rhenium metal with technical grade (i.e., N a containing) K O , in a modified Belt-type apparatus (20 kbar, 1Ö00 °C, 60 min, Au capsule). The amber-coloured crystals are very hygroscopic and decompose rapidly when exposed to air. K 3N aR e20 9 crystallizes hexago-nally, space group P 63/mmc, with a = 6.012(1), c = 14.342(14)Ä, c/a = 2.386 and Z = 2. The structure was refined to R = 0.031, R w = 0.023 for 422 independent, absorption-corrected reflections with l> a (I). K 3N aR e20 9 is isostructural with 6 H -B a T i0 3, a perowskite variant, and contains Na and Re in octaedral coordination. Two R e 0 6 octahedra are face-sharing, thus creating a Re20 9 double octahedron with a R e -R e distance of 2.92Ä. | |
