Darstellung und Eigenschaften von Alkali‐ und Erdalkali‐oxorhenaten(VII) mit den „Sauerstoffzahlen”︁ 5 und 6 werden beschrieben. Die Individualität der einzelnen Verbindungen, die mit den entsprechenden Oxojodaten (VII) und Oxoosmaten (VII)3) isotyp sind, konnte sowohl chemisch wie röntgenographisch sichergestellt werden.

Alkali and alkaline-earth oxorhenates(VI1) and oxorhenates-(VI) were prepared by thermal reaction of appropriate miutures in the solid phase. They were unequivocally differentiated by quantitative analysis, X-ray analyses (as far as possible by determination of the lattice parameters), and in some cases by determination of their solubilities in absolute methanol. In addition to tetraoxorhenates(VI1) of the type MeIRe04 and Mer1(Re0& (Me = metal cation), penta-and hexaoxorhenates containing Rev11 were prepared by thermal reaction of the corresponding tetraoxorhenate(VI1) with oxides or carbonates of Li, Na, Ba, Sr, or Ca; in order to obtain K3Re05, KOH was used as the basic component. Pentaoxorhenates of the type Me:ReO5 or My(ReOS)2 were obtained with Na and K as Me1 and Ba and Sr as MeTI. Na3ReOSand K3ReO5 are isotypes of the corresponding osmates(VI1) [4]; furthermore, the compound K3105, which is isotypic with K3Re05, was prepared for the first time. There are two modifications of Ba3(Re05)2. Hexaoxorhenates of the type Me: Re06 or Mey(Re06)2 (Me1 = Li, Na; Me11 = Ba, Sr, Ca) are isotypic with the corresponding osmates(VI1) 141 and iodates(VI1). Li5ReO6 was assigned to the hexagonal system (lattice constants: a0 = 5.053 A, co = 14.21 A, cia = 2.81).The yellow to orange color of oxorhenates(VI1) with higher oxygen co-ordinztion is noteworthy, in contrast to the tetraoxorhenates, which are colorless; they are split immediately by water into tetraoxorhenates(VI1) and free base. Rhenates containing Rev1 are obtained by interaction of oxorhenates(VII), metallic Re, and the appropriate quantity of a basic oxide. In the system LizO-ReO3, the compounds Li4ReOs and &Re06 both exist in two modifications. The low-temperature form of Li4ReO5 has the Lang structure [51 and probably has the formula Li~[Re0.&i0.4]03, while a-Li4ReOs is isotypic with Li4WO5 [6] and Li4TeO5 171. The fact that P-LisReOs and Li~Re06 are clearly isotypes is worthy of note (lattice constants of P-Lis~eOs: a0 = 5.03 A, co = 14.12 A, c/a = 2.81). The compound Li4MgReO6 was also prepared for the first time and has the same type of structure. Li6oso6 [S] crystallizes in a similar lattice. cc-Li6ReO6 is isotypic with Li6wo6 161; it cannot be indexed from its powder diagram. Received, March 13th, 1963 [Z 466/295 IEI In the ternary system Me-Re-0, there are compounds with the orderedperovskitestructure and thecomposition Me3Re06 (Me = Ba, Sr, Ca) 131. However, of these only Ba3ReO6, which was obtained in two tetragonal modifications, could be indexed from a powder diagram. Of the compounds of the type Me'Me"ReO6, all the combinations with Me' = Ba, Sr, or Ca and Me" = Ba, Sr, Ca, or Mg wcre prepared (partly in agreement with the results of Ward [41); all the compounds possess the ordered perovskite structure. Furthermore, a rhombohedral phase Ba3ReO,j-0.3BaO was obtained pure. Compounds ofthe type MeSRezOli (Me = Sr or Ca) also possess the perovskite structure. The new compounds BaZReOS (isotypic with BazX05, X = Te, Mo, W, or 0 s ) [ 5 ] and SrzReOs...

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