Über Perrhenate. 3 Zum Aufbau des Mesoperrhenates Na3[ReO5]

About Perrhenates. 3 On the Structure of the Mesoperrhenate Na₃ReO₅] By tempering powder samples (prepared from mixtures of binary oxides: Na₂O₂/ReO₂ and Na₂O/ReO₃ respectively, Na : Re = 3 : 1, Ar and O₂ atmosphere respectively, 400–450°C, corundum boat) in a closed Ag cylinder (500–550°C, 10 d) yellow single crystals of Na₃ReO₅, sensitive to moisture, were grown. The compound crystallizes trigonal, space group P3₁, P3₂ respectively, with a = 5.544(1), c = 13.580(7) Å, Z = 3, d_rö. = 4.62 g/cm³. The crystal structure 4-circle diffractometer data, 1091 I₀(hkl), AgKα, R = 6.14, R_w = 6.08%] is characterized by “isolated” bipyramids ReO₅. Na⁺ ions are occupying all the tetrahedral (Na2, Na3) and octahedral (Na1) holes of the pseudocubic face centred (c/a = 2.441) Re part of the lattice; resulting in a Na₃Re kation framework corresponding to the Li₃Bi type of structure. Effective Coordination Numbers (ECoN), the Madelung Part of Lattice energy (MAPLE) and the charge distribution (CHARDI) are computed and discussed.