OXIDATION OF INTERMETALLIC PHASES - K4(NA 2[TL2O6]) FROM NATL AND K2O2

The hitherto unknown K4{[Tl2O6]} was prepared in form of transparent, yellow single crystals from NaTl and KO1,08 (molar ratio 1: 1.3; seale d Ag-cylinder; 450-degrees-C, 30 d). The structure determination (four -circle diffractometer, MoKalpha, 1280 out of 1523 I(o)(hkl), R = 5.75 %, R(w) = 4.58%) confirms the space group P2(1)/c with a = 641.3 pm, b = 691.1 pm, c = 1188.5 pm, beta = 95.69-degrees and Z = 2. As charact eristic building units of the structure there are doubles of tetrahedr a of [Tl2O6] and [Na2O6]. The compound is isotypic with CS6[In2O6] and Rb6[T2lO6]. The Madelung Part of Lattice Energy, MAPLE, the Mean Fict ive Ionic Radii, MEFIR, Effective Coordination Numbers, ECoN, and Char ge Distribution, CHARDI, are calculated.