Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9617835 | Microporous and Mesoporous Materials | 2005 | 7 Pages |
Abstract
Crystals of a new framework uranyl molybdate, [(C2H5)2NH2]2[(UO2)4(MoO4)5(H2O)](H2O), were synthesized from a solution of UO2(CH3COO)2 · 2H2O, MoO3, diethylamine and HCl in H2O at 220 °C. The structure was studied at â127 °C. The compound is hexagonal, space group P6522, a = 11.3612(13), c = 52.698(8) Ã
, VÂ =Â 5890.7(13)Â Ã
3, ZÂ =Â 3. The structure has been refined to R1Â =Â 0.050 (wR2Â =Â 0.100; SÂ =Â 0.985) on the basis of 3103 unique observed reflections. The structure consists of a three-dimensional framework of composition [(UO2)4(MoO4)5(H2O)]2â that consists of UO7 pentagonal bipyramids that share equatorial corners with MoO4 tetrahedra. The framework contains a three-dimensional system of channels. The first system of channels is parallel to [0Â 0Â 1] and has the dimensions 7.0Â ÃÂ 7.0Â Ã
, which result in a crystallographic free diameter (effective pore width) of 4.3Â ÃÂ 4.3Â Ã
(based on an oxygen radius of 1.35Â Ã
). Other channels run parallel to [1Â 0Â 0], [1Â 1Â 0] and [0Â 1Â 0] and have dimensions 5.2Â ÃÂ 7.1Â Ã
(giving an effective pore width of 2.5Â ÃÂ 4.4Â Ã
). One symmetrically unique [(C2H5)2NH2]+ cation and H2O molecule reside in the framework cavities. The channels parallel to [0 0 1] are chiral and are centered about a 65 screw axis. The uranyl framework with U:Mo = 4:5 in the structure of [(C2H5)2NH2]2[(UO2)4(MoO4)5(H2O)](H2O) represents the third known type of chiral uranyl molybdate framework. Its relationships to the frameworks with U:Mo = 5:7 and 6:7 can be understood in terms of fundamental chains that have related but yet different topological structure.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Catalysis
Authors
Sergey V. Krivovichev, Christopher L. Cahill, Evgeniy V. Nazarchuk, Peter C. Burns, Th. Armbruster, Wulf Depmeier,