Geometrical isomerism in uranyl chromates I. Crystal structures of (UO2)(CrO4)(H2O)2, [(UO2)(CrO4)(H2O)2](H2O) and [(UO2)(CrO4)(H2O)2]4(H2O)9
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Sergey V. Krivovichev
Abstract
Three uranyl chromate hydrates, (UO2)(CrO4)(H2O)2, [(UO2)(CrO4)(H2O)2](H2O) and [(UO2)(CrO4)(H2O)2]4(H2O)9, have been prepared by evaporation from aqueous solutions. The crystal structure of (UO2)(CrO4)(H2O)2 (monoclinic, C2/m, Z = 16, a = 16.786(2), b = 22.731(2), c = 6.9969(7) Å, β = 90.051(3)°, V = 2669.8(5) Å3) has been solved by direct methods and refined to R1 = 0.065, calculated for 6702 unique observed reflections (|Fo| ≥ 4σF). The crystal structure of [(UO2)(CrO4)(H2O)2](H2O) (monoclinic, P21, Z = 4, a = 9.7206(14), b = 7.1617(10), c = 11.0909(16) Å, β = 92.388(3)°, V = 771.43(19) Å3) has been solved by direct methods and refined to R1 = 0.052, calculated for 4879 unique observed reflections (|Fo| ≥ 4σF). The crystal structure of [(UO2)(CrO4)(H2O)2]4(H2O)9 (monoclinic, P21/c, Z = 4, a = 31.397(1), b = 7.1701(3), c = 16.2480(7) Å, β = 97.515(1)°, V = 3626.3(3) Å3) has been solved by direct methods and refined to R1 = 0.051, calculated for 8164 unique observed reflections (|Fo| ≥ 4σF). Each structure contains chains of composition [(UO2)(CrO4)(H2O)2]. Within the chains, (UO2)O3(H2O)2 pentagonal bipyramids share three equatorial O atoms with CrO4 tetrahedra. The CrO4 tetrahedra in the [(UO2)(CrO4)(H2O)2] chains each share three corners with uranyl polyhedra, and contain one non-shared (terminal) ligand pointing either up or down relative to the plane of the chain. This results in a geometrical isomerism of the uranyl chromate chains that can be described as a sequence of tetrahedra orientations along the chain extension, e.g. ... up-down-up-down ... or ... ududud .... [or (ud)∞]. The structures of (UO2)(CrO4)(H2O)2 and [(UO2)(CrO4)(H2O)2](H2O) are based upon the chains of the (ud)∞ type, whereas [(UO2)(CrO4)(H2O)2]4(H2O)9 contains two types of chains: (ud)∞ and (u)∞. The [(UO2)(CrO4)(H2O)2] chains extend in the same direction in each structure and are linked via hydrogen bonds involving H2O molecules.
© 2003 Oldenbourg Wissenschaftsverlag GmbH
Artikel in diesem Heft
- Strukturverwandtschaft durch Streckung in Richtung von Symmetrieachsen
- Electron crystallography of zeolites. 2. Mordenite and the role of secondary scattering on structure determination
- Rietveld refinement of incommensurate low tridymite
- Crystal structure determination of systematically intergrown compounds: Li5(OH)2Br3 and Li2(OH)Br
- Wickenburgite, a double-layer silicate Pb3Al[6][Ca[6]Al[4]Si[4]10O27(H2O)3]·H2O: Crystal chemistry and thermal behaviour
- Natural and synthetic compounds with kröhnkite-type chains. An update
- Geometrical isomerism in uranyl chromates I. Crystal structures of (UO2)(CrO4)(H2O)2, [(UO2)(CrO4)(H2O)2](H2O) and [(UO2)(CrO4)(H2O)2]4(H2O)9
- Structure characterization of molecular complexes for non-linear optical materials I. X-ray analysis and AM1 calculations of 1 : 1 complexes of 8-hydroxiquinoline (1) and isonicotinamide (2) with 2,4,6-trinitrophenol
- The twinned and disordered crystal structure of tetrakis(triphenylphosphine)silver(I)bis(trifluoroacetato)triphenylstannate(IV)
Artikel in diesem Heft
- Strukturverwandtschaft durch Streckung in Richtung von Symmetrieachsen
- Electron crystallography of zeolites. 2. Mordenite and the role of secondary scattering on structure determination
- Rietveld refinement of incommensurate low tridymite
- Crystal structure determination of systematically intergrown compounds: Li5(OH)2Br3 and Li2(OH)Br
- Wickenburgite, a double-layer silicate Pb3Al[6][Ca[6]Al[4]Si[4]10O27(H2O)3]·H2O: Crystal chemistry and thermal behaviour
- Natural and synthetic compounds with kröhnkite-type chains. An update
- Geometrical isomerism in uranyl chromates I. Crystal structures of (UO2)(CrO4)(H2O)2, [(UO2)(CrO4)(H2O)2](H2O) and [(UO2)(CrO4)(H2O)2]4(H2O)9
- Structure characterization of molecular complexes for non-linear optical materials I. X-ray analysis and AM1 calculations of 1 : 1 complexes of 8-hydroxiquinoline (1) and isonicotinamide (2) with 2,4,6-trinitrophenol
- The twinned and disordered crystal structure of tetrakis(triphenylphosphine)silver(I)bis(trifluoroacetato)triphenylstannate(IV)
