DOI

Two new mixed alkaline uranyl molybdates CsNa3[(UO 2)4O4Mo2O8] (1) and Cs2Na8[(UO2)8O8(Mo 5O20)] (2) have been obtained by high-temperature solid state reactions. Their crystal structures have been solved by direct methods: Compound 1: triclinic, P1, a = 6.46(1), b = 6.90(1), c = 11.381.(2) Å, α = 84.3(1), β = 91.91(1), γ = 80.23(1)°, V = 488.6(2) Å3, R1 = 0.06 for 2865 unique reflections with |F0| & 4σF; Compound 2: orthorhombic, Ibam, a = 6.8460(2), b = 23.3855(7), c = 12.3373(3) Å, V = 1975.2(1) Å3, R1 = 0.049 for 2120 unique reflections with. |F0| ≥ 4σF. The structure of 1 contains complex sheets of UrO5 pentagonal bipyramids and molybdenum polyhedra. The sheets have [(UO2)2O2(MoO5)] composition. Natrium and cesium atoms are located in the interlayer space. Cesium atoms are situated between the molybdenum, clusters, whereas natrium atoms are segregated between the uranyl complexes. The large Cs+ ions are localized between, the Mo2O9 groups and force the molybdenum polyhedra to rotate relative to the [(UO2J 2O2(MoO5)] sheets. Such rotation is impossible for U6+ polyhedra due to their rigid edgesharing complexes. The distance between the U6+ polyhedra vertices of neighboring layers is 3.8 Å, that allows the Na+ ion to be positioned between the uranyl groups. The crystal structure of 2 is based upon a framework consisting of [(UO2)2O2(MoO5)] sheets parallel to (010). The sheets are linked into a 3-D framework by sharing vertices with the Mo(2)O4 tetrahedra, located between the sheets. Each MoO 4 tetrahedron shares two of its corners with two MoO6 octahedra in the sheet above, and the other two with MoO6 octahedra of the sheet below. Thus four MoO6 octahedra and one MoO4 tetrahedron form chains of composition Mo5O18. The resulting framework has a system of channels occupied by the Cs+ and Na+ ions.

Язык оригиналаанглийский
Страницы (с-по)1231-1235
Число страниц5
ЖурналZeitschrift fur Anorganische und Allgemeine Chemie
Том635
Номер выпуска8
DOI
СостояниеОпубликовано - июл 2009

    Предметные области Scopus

  • Неорганическая химия

ID: 5394616