Organically Templated Layered Uranyl Molybdate [C3H9NH+]4[(UO2)3(MoO4)5] Structurally Based on Mineral-Related Modular Units

Three new rubidium polychromates, Rb2[(UO2)(Cr2O7)(NO3)2] (1), γ-Rb2Cr3O10 (2) and δ-Rb2Cr3O10 (3) were prepared by combination of hydrothermal treatment at 220 °C and evaporation of aqueous solutions under ambient conditions. Compound 1 is monoclinic, P 2 1 / c $P{2}_{1}/c$ , a = 13.6542(19), b = 19.698(3), c = 11.6984(17) Å, β = 114.326(2)°, V = 2867.0(7) Å3, R 1 = 0.040; 2 is hexagonal, P 6 3 / m $P{6}_{3}/m$ , a = 11.991(2), c = 12.828(3) Å, γ = 120°, V = 1597.3(5) Å3, R 1 = 0.031; 3 is monoclinic, P 2 1 / n $P{2}_{1}/n$ , a = 7.446(3), b = 18.194(6), c = 7.848(3) Å, β = 99.953(9)°, V = 1047.3(7) Å3, R 1 = 0.037. In the crystal structure of 1, UO8 bipyramids and NO3 groups share edges to form [(UO2)(NO3)2] species which share common corners with dichromate Cr2O7 groups producing novel type of uranyl dichromate chains [(UO2)(Cr2O7)(NO3)2]2−. In the structures of new Rb2Cr3O10 polymorphs, CrO4 tetrahedra share vertices to form Cr3O10 2− species. The trichromate groups are aligned along the 63 screw axis forming channels running in the ab plane in the structure of 2. The Rb cations reside between the channels and in their centers completing the structure. The trichromate anions are linked by the Rb+ cations into a 3D framework in the structure of 3. Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems is discussed.

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Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems: synthesis and crystal structures of Rb₂[(UO₂)(Cr₂O₇)(NO₃)₂] and two new polymorphs of Rb₂Cr₃O₁₀

Nazarchuk

Siidra

Charkin

et al. 2021

Zeitschrift Für Kristallographie - Crystalline Materials

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Uranyl silicate nanotubules in Rb₂[(UO₂)₂O(Si₃O₈)]: synthesis and crystal structure

Nazarchuk,

Siidra,

Charkin

et al. 2023

Zeitschrift Für Kristallographie - Crystalline Materials

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A new rubidium uranyl silicate, Rb2(UO2)2O(Si3O8) (1), was obtained using high-temperature approach from the melt in silica tubes. Its crystal structure was solved by direct methods: hexagonal, P6/m, a = 27.7992(7), c = 7.2346(2) Å, V = 4841.8(3) Å3, R 1 = 0.033. The structure of 1 represents a new structure type with unprecedented topology not observed before among U(VI) oxides and oxysalts. It is comprised of layers with large voids derived from the U3O8 structure formed exclusively by pentagonal UrO5 bipyramids. The low-occupied Rb sites are located in the interlayer space. The SiO4 silicate tetrahedra in the structure of 1 share vertices to form rolled [Si6O16]8− chains. The nanotubules [(UO2)(Si6O16)]6− penetrate through both U3O8-derived layers and Rb interlayer. These tubules are attached to the U3O8 derived sheets via uranyl-uranyl interactions and edge-sharing between silicate tetrahedra and UrO5 bipyramids.

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Crystal Chemistry and Structural Complexity of the Uranyl Molybdate Minerals and Synthetic Compounds

Kuporev,

Kalashnikova,

Gurzhiy

2023

Crystals

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This paper reviews not the largest, but at the same time quite an interesting, group of natural and synthetic uranyl molybdate compounds. Nowadays, nine minerals of U and Mo are known, but the crystal structures have only been reported for five of them. Almost an order of magnitude more (69) synthetic compounds are known. A significant discrepancy in the topological types for natural and synthetic phases is shown, which is most likely due to elevated temperatures of laboratory experiments (up to 1000 °C), while natural phases apparently grow at significantly lower temperatures. At the same time, the prevalence of dense topologies (with edge-sharing interpolyhedral linkage) among natural phases can be noted, which is fully consistent with other recently considered mineral groups. Uranyl molybdates demonstrate several similarities with compounds of other U-bearing groups; however, even topological matches do not lead to the appearance of completely isotypic compounds. Structural complexity calculations confirm, in general, crystal chemical observations. Considering the prevalence of dense structures in which coordination polyhedra of uranium and molybdenum are connected through common edges as well as framework architectures, one can expect a less significant influence of interlayer species on the formation of the crystal structure than the main U-bearing complexes. The more structural complexity of the uranyl molybdate units, the more complex of the entire crystal structure is. In addition, there is a tendency for complexity to increase with increasing density of the complex; the simplest structures are vertex-shared, while the complexity increases with the appearance of common edges.

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Organically Templated Layered Uranyl Molybdate [C3H9NH+]4[(UO2)3(MoO4)5] Structurally Based on Mineral-Related Modular Units

Cited by 3 publications

References 49 publications

Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems: synthesis and crystal structures of Rb₂[(UO₂)(Cr₂O₇)(NO₃)₂] and two new polymorphs of Rb₂Cr₃O₁₀

Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems: synthesis and crystal structures of Rb₂[(UO₂)(Cr₂O₇)(NO₃)₂] and two new polymorphs of Rb₂Cr₃O₁₀

Uranyl silicate nanotubules in Rb₂[(UO₂)₂O(Si₃O₈)]: synthesis and crystal structure

Crystal Chemistry and Structural Complexity of the Uranyl Molybdate Minerals and Synthetic Compounds

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Organically Templated Layered Uranyl Molybdate [C3H9NH+]4[(UO2)3(MoO4)5] Structurally Based on Mineral-Related Modular Units

Cited by 3 publications

References 49 publications

Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems: synthesis and crystal structures of Rb2[(UO2)(Cr2O7)(NO3)2] and two new polymorphs of Rb2Cr3O10

Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems: synthesis and crystal structures of Rb2[(UO2)(Cr2O7)(NO3)2] and two new polymorphs of Rb2Cr3O10

Uranyl silicate nanotubules in Rb2[(UO2)2O(Si3O8)]: synthesis and crystal structure

Crystal Chemistry and Structural Complexity of the Uranyl Molybdate Minerals and Synthetic Compounds

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Product

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Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems: synthesis and crystal structures of Rb₂[(UO₂)(Cr₂O₇)(NO₃)₂] and two new polymorphs of Rb₂Cr₃O₁₀

Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems: synthesis and crystal structures of Rb₂[(UO₂)(Cr₂O₇)(NO₃)₂] and two new polymorphs of Rb₂Cr₃O₁₀

Uranyl silicate nanotubules in Rb₂[(UO₂)₂O(Si₃O₈)]: synthesis and crystal structure