Low‐Dimensional Structural Units in Amine‐Templated Uranyl Oxoselenates(VI): Synthesis and Crystal Structures of [C3H12N2][(UO2)(SeO4)2(H2O)2](H2O), [C5H16N2]2[(UO2)(SeO4)2(H2O)](NO3)2, [C4H12N][(UO2)(SeO4)(NO3)], and [C4H14N2][(UO2)(SeO4)2(H2O)] |
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| Authors: | Sergey V Krivovichev Volker Kahlenberg |
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| Abstract: | The crystals of four amine‐templated uranyl oxoselenates(VI), C3H12N2](UO2)(SeO4)2(H2O)2](H2O) ( 1 ), C5H16N2]2(UO2)(SeO4)2(H2O)](NO3)2 ( 2 ), C4H12N](UO2)(SeO4)(NO3)] ( 3 ), and C4H14N2](UO2)(SeO4)2(H2O)] ( 4 ) were prepared by evaporation from aqueous solution of uranyl nitrate, selenic acid and the respective amine. The crystal structures of all four compounds have been solved by direct methods from X‐ray diffraction data. The structure of 1 (triclinic, , a = 7.5611(16), b = 7.7650(17), c = 12.925(3) Å, α = 94.605(18), β = 94.405(17), γ = 96.470(17)°, V = 748.8(3) Å3, R1 = 0.029 for 2769 unique observed reflections) is based upon 0D‐units of the composition (UO2)2(SeO4)4(H2O)4]4?. These discrete units are composed from two pentagonal UO7]8? bipyramids linked via SeO4]2? tetrahedra and are unknown in structural chemistry of uranium so far. The structure of 2 (monoclinic, C2/c, a = 28.916(5), b = 8.0836(10), c = 11.9856(16) Å, β = 110.909(11)°, V = 2617.1(6) Å3, R1 = 0.035 for 2578 unique observed reflections) contains (UO2)(SeO4)2(H2O)]2? chains of corner‐sharing pentagonal UO7]8? bipyramids and SeO4]2? tetrahedra. The chains run parallel to the c axis and are arranged into layers parallel to (100). In the structure of 3 (monoclinic, C2/m, a = 21.244(5), b = 7.1092(11), c = 8.6581(18) Å, β = 97.693(17)°, V = 1295.8(4) Å3, R1 = 0.027 for 1386 unique observed reflections), pentagonal UO7]8? bipyramids share corners with three SeO4]2? tetrahedra each and an edge with a NO3]? anion to form (UO2)(SeO4)(NO3)]? chains parallel to the b axis. In the structure of 4 (triclinic, , a = 6.853(2), b = 10.537(3), c = 10.574(3) Å, α = 99.62(3), β = 94.45(3), γ = 100.52(3)°, V = 735.6(4) Å3, R1 = 0.045 for 2713 unique observed reflections), one symmetrically independent pentagonal UO7]8? bipyramid shares corners with four SeO4]2? tetrahedra to form the (UO2)(SeO4)2(H2O)]2? chains parallel to the a axis. A comparison to related uranyl compounds is given. |
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| Keywords: | Uranium Selenium Uranyl oxoselenates Crystal structures |
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