Synthesis, Crystal Structures and Properties of Na₂ReO₃ and of a Second Modification of Na₅ReO₆.

Abstract

Structure D 2000Synthesis, Crystal Structures and Properties of Na 2 ReO 3 and of a Second Modification of Na5ReO6. -Single crystals of Na5ReO6 (modification denoted II) are obtained from the reaction of Na2O and Re metal in the presence of CdO at 550°C (Ag container, 5 d). At 700°C, Na2ReO3 is formed, possibly via a topotactic redox reaction of Na5ReO6 with rhenium metal. Na5ReO6-II crystallizes in the orthorhombic space group Fddd with Z = 8 and differs from Na 5 ReO 6 -I in the ordering of the cations. Na2ReO3 crystallizes in the hexagonal space group P63/mcm with Z = 4. The structure contains [Re2O6] 4anions with Re≡Re dumbbells in a trigonal prismatic environment of oxygen. -(SOBOTKA, B. M.; MUDRING, A.-V.; MOELLER*, A.; Z. Anorg.