ON MIXED-COORDINATED ISOLATED ANIONS .2. A NEW TYPE OF OXORUTHENATES(VI) - CSK5RU2O9 = CSK5[RUO5][RUO4]

By heating of intimate mixtures of the oxides [KO1.1, CsO1.2, RuO2; K: Cs: Ru = 2.2: 1:1; Ag-tube, 750-degrees-C, 34d] dark-green single crystals of CsK5Ru2O9 = CsK5[RuO5][RuO4] were obtained for the first time. Ru6+ shows two different polyhedra in this oxide (tetrahedron, trigonal bipyramid). Untill now Rb6[TeO5][TeO4] [1] next to "Mg4GeO6" [3] and the isotypic high-pressure silicate [4] was the only examples known. The structure was determined by four-circle diffractometer data [Mo-KalphaBAR, 1824 from 1949 I0(hkl), SG: Pnma, R = 12.6%, R(w) = 4.5%], parameters see text. Guinier-Simon data gave a = 1701.6(3), b = 827.6(1), c = 905.7(1) pm, Z = 4. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these calculated via Mean Fictive Ionic Radii, MEFIR, were calculated and discussed.