Über quaternäre Oxowolframate (VI) Na6Li2[W2O10] - ein Diwolframat

On Quaternary Oxotungstates (VI). Na₆Li₂W₂O₁₀] — a Ditungstate For the first time, Na₆Li₂W₂O₁₀] has been prepared by annealing mixtures of WO₃, Na₂O and Li₂O with W:Na:Li = 1:3:1 closed Pt-tube in quartz-glass ampoule, 840°C, 60 d (single crystals)]. The colourless crystals are of squatted shape. The structure determination 1813/I₀(h kl), four-cycle diffractometer PW 1100 (Fa. Philips), ω-scan, AgK_α, R = 8.32%, absorption not considered] confirms the space group P1 with a = 784.66(11), b = 602.53(7) c, = 563.81(11) pm α = 106.784(14)°, β = 114.548(14)°, γ = 91.082(13)°, Z = 2, d_x = 4.92 g · cm^?3, d^pyk = 4.85 g · cm^?3. The structure may be described as a distorted derivative of the NaCl-type. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, are calculated and discussed.