Chiral open-framework uranyl molybdates. 2. Flexibility of the U : Mo=6 : 7 frameworks: syntheses and crystal structures of (UO2)(0.82) C8H20N (0.36) (UO2)(6)(MoO4)(7)(H2O)(2) (H2O)(n) and C6H14N2 (UO2)(6)(MoO4)(7)(H2O)(2) (H2O)(m)

Krivovichev, S. V., Burns, P. C., Armbruster, T., Nazarchuk, E. V. and Depmeier, W. (2005) Chiral open-framework uranyl molybdates. 2. Flexibility of the U : Mo=6 : 7 frameworks: syntheses and crystal structures of (UO2)(0.82) C8H20N (0.36) (UO2)(6)(MoO4)(7)(H2O)(2) (H2O)(n) and C6H14N2 (UO2)(6)(MoO4)(7)(H2O)(2) (H2O)(m) Microporous and Mesoporous Materials, 78 (2-3). pp. 217-224. DOI 10.1016/j.micromeso.2004.10.019.

Full text not available from this repository.

Supplementary data:

Abstract

Two new chiral open-framework uranyl molybdates, (UO2)(0.82)[C8H20N](0.36)[(UO2)(6)(MoO4)(7)(H2O)(2)](H2O)(n) (1) and [C6H14N2][(UO2)(6)(MoO4)(7)(H2O)(2)](H2O)(m) (2) have been synthesized by hydrothermal methods. The structures of 1 and 2 have been refined using X-ray diffraction data collected at -127degreesC. The structure of 1 [orthorhombic, C222(1), a = 12.2303(15) b = 18.966(2) c = 22.392(3) Angstrom, V = 5194.0(11) Angstrom(3)] has been refined to R-1 = 0.043 on the basis of 4126 unique observed reflections. The structure of 2 [orthorhombic, C222(1), a = 11.3256(15), b = 19.860(3), c = 23.731(3) Angstrom, V = 5337.8(12) Angstrom(3)] has been refined to R-1 = 0.056 on the basis of 3519 unique observed reflections. The structures of 1 and 2 are based upon complex chiral [(UO2)(6)(MoO4)(7)(H2O)(2)] frameworks of corner-sharing UO7 bipyramids and MoO4 tetrahedra. In addition to framework U sites, the structure of 1 contains an additional, partially-occupied and disordered U(4) site, located within the framework cavities and coordinated by several disordered anions to form the complex [(UO7)(H2O)(5)](2+) cation. The structure of 2 contains disordered DABCO (1,4-diazabicyclo[2.2.2]-octane) molecules. The geometrical parameters of the uranyl molybdate frameworks in the structures of 1 and 2 are significantly different. The a parameter of 1 is about 0.9 Angstrom longer than that of 2, whereas the b and c parameters of 1 are shorter than those of 2 (similar to0.9 and 1.3 Angstrom, respectively). This occurs due to the adaptation of the [(UO2)(6)(MoO4)(7)(H2O)(2)](2-) framework to the shape of the complex [(UO2)(H2O)(5)](2+) cation in 1. Analysis of the U-O-Mo bond angles of the frameworks indicates the U-O(15)-Mo and U-O(20)Mo links are the most flexible. The transition from 2 to 1 involves an increase of the U-O(15)-Mo and U-O(20)-Mo angles from 146.7degrees to 169.0degrees and from 151degrees to 171degrees, respectively. (C) 2004 Elsevier Inc. All rights reserved.

Document Type: Article
Keywords: uranyl molybdates open framework crystal structure chiral flexibility secondary building units chemistry
Research affiliation: Kiel University
Refereed: Yes
DOI etc.: 10.1016/j.micromeso.2004.10.019
ISSN: 1387-1811
Date Deposited: 18 Jan 2012 05:38
Last Modified: 28 Mar 2018 10:16
URI: http://eprints.uni-kiel.de/id/eprint/16067

Actions (login required)

View Item View Item