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Mixed-Metal Uranium(VI) Iodates:  Hydrothermal Syntheses, Structures, and Reactivity of Rb[UO2(CrO4)(IO3)(H2O)], A2[UO2(CrO4)(IO3)2] (A = K, Rb, Cs), and K2[UO2(MoO4)(IO3)2]

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journal contribution
posted on 11.09.2002, 00:00 by Richard E. Sykora, Steven M. McDaniel, Daniel M. Wells, Thomas E. Albrecht-Schmitt
The reactions of the molecular transition metal iodates A[CrO3(IO3)] (A = K, Rb, Cs) with UO3 under mild hydrothermal conditions provide access to four new, one-dimensional, uranyl chromatoiodates, Rb[UO2(CrO4)(IO3)(H2O)] (1) and A2[UO2(CrO4)(IO3)2] (A = K (2), Rb (3), Cs (4)). Under basic conditions, MoO3, UO3, and KIO4 can be reacted to form K2[UO2(MoO4)(IO3)2] (5), which is isostructural with 2 and 3. The structure of 1 consists of one-dimensional [UO2(CrO4)(IO3)(H2O)]- ribbons that contain uranyl moieties bound by bridging chromate and iodate anions as well as a terminal water molecule to create [UO7] pentagonal bipyramidal environments around the U(VI) centers. These ribbons are separated from one another by Rb+ cations. When the iodate content is increased in the hydrothermal reactions, the terminal water molecule is replaced by a monodentate iodate anion to yield 24. These ribbons can be further modified by replacing tetrahedral chromate anions with MoO42- anions to yield isostructural, one-dimensional [UO2(MoO4)(IO3)2]2- ribbons. Crystallographic data:  1, triclinic, space group P1̄, a = 7.3133(5) Å, b = 8.0561(6) Å, c = 8.4870(6) Å, α = 88.740(1)°, β = 87.075(1)°, γ = 71.672(1)°, Z = 2; 2, monoclinic, space group P21/c, a = 11.1337(5) Å, b = 7.2884(4) Å, c = 15.5661(7) Å, β = 107.977(1)°, Z = 4; 3, monoclinic, space group P21/c, a = 11.3463(6) Å, b = 7.3263(4) Å, c = 15.9332(8) Å, β = 108.173(1)°, Z = 4; 4, monoclinic, space group P21/n, a = 7.3929(5) Å, b = 8.1346(6) Å, c = 22.126(2) Å, β = 90.647(1)°, Z = 4; 5, monoclinic, space group P21/c, a = 11.3717(6) Å, b = 7.2903(4) Å, c = 15.7122(8) Å, β = 108.167(1)°, Z = 4.

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