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Single crystals of four novel uranyl selenate and selenite-selenate oxysalts with protonated ethylamine molecules, (C 2 H 8 N) 2 [(UO 2 )(SeO 4 ) 2 (H 2 O)](H 2 O) ( I ), (C 2 H 8 N) 3 [(UO 2 )(SeO 4 ) 2 (HSeO 4 )] ( II ), (C 2 H 8 N)[(UO 2 )(SeO 4 )(HSeO 3 )] ( III ), and (C 2 H 8 N)(H 3 O)[(UO 2 )(SeO 4 ) 2 (H 2 O)] ( IV ) have been prepared by isothermal evaporation from aqueous solutions. Uranyl-containing 1D and 2D units have been investigated using topological approach and information-based complexity measurements that demonstrate the evolution of structural units and the increase of topological complexity with the decrease of H 2 O content. [ABSTRACT FROM AUTHOR]

Abstract: Four new Li uranyl phosphates and arsenates have been prepared by high-temperature solid-state reactions: α-Li[(UO2)(PO4)] (1), α-Li[(UO2)(AsO4)] (2), β-Li[(UO2)(AsO4)] (3) and Li2[(UO2)3(P2O7)2] (4). The structures of the compounds have been solved by direct methods: 1—triclinic, , a=5.0271(1)Å, b=9.8799(2)Å, c=10.8920(2)Å, α=108.282(9)°, β=102.993(8)°, γ=104.13(1)°, V=470.69(2)Å3, Z=4, R 1=0.0415 for 2786 unique reflections with |F 0|⩾4σF ; 2—triclinic, , a=5.129(2)Å, b=10.105(3)Å, c=11.080(3)Å, α=107.70(2)°, β=102.53(3)°, γ=104.74(3)°, V=501.4(3)Å3, Z=4, R 1=0.055 for 1431 unique reflections with |F 0|⩾4σ F; 3—triclinic, , a=5.051(1)Å, b=5.303(1)Å, c=10.101(1)Å, α=90.31(1)°, β=97.49(1)°, γ=105.08(1)°, V=258.80(8)Å3, Z=2, R 1=0.0339 for 2055 unique reflections with |F 0|⩾4σ F; 4—triclinic, , a=5.312(1)Å, b=6.696(1)Å, c=12.542(1)Å, α=94.532(9)°, β=99.059(8)°, γ=110.189(7)°, V=409.17(10)Å3, Z=2, R 1=0.0565 for 1355 unique reflections with |F 0|⩾4σ F. The structures of all four compounds are based upon 3-D frameworks of U and T polyhedra (T=P, As). Phases 1 and 2 are isostructural and consist of U2O12 dimers and UO6 square bipyramids linked by single TO4 tetrahedra. The structure of 3 consists of 3-D framework of corner-sharing UO6 bipyramids and AsO4 tetrahedra. In the structure of 4, the framework is composed of U2O12 dimers, UO6 bipyramids and P2O7 dimers. In all the compounds, Li+ cations reside in framework cavities. The topologies of the 3-D frameworks can be described as derivatives of the PtS (cooperite) network. [Copyright &y& Elsevier]

Phase formation in the mixed sulfate-selenate aqueous system of uranyl nitrate and cesium nitrate has been investigated. Two types of crystalline compounds have been obtained and characterized using a number of experimental (single crystal XRD, FTIR, SEM) and theoretical (information-based complexity calculations, topological analysis) techniques. No miscibility gaps have been observed for Cs 2 [(UO 2 ) 2 ( T O 4 ) 3 ] ( T = S, Se), which crystallizes in tetragonal system, P -42 1 m , a =9.616(1)–9.856(2), c =8.105(1)–8.159(1) Å, V =749.6(2)–792.5(3) Å 3 . Nine phases with variable amount of S and Se have been structurally characterized. The structures of the Cs 2 [(UO 2 ) 2 ( T O 4 ) 3 ] ( T = S, Se) compounds are based upon the [(UO 2 ) 2 ( T O 4 ) 3 ] 2- layers of corner-sharing uranyl pentagonal bipyramids and T O 4 tetrahedra. The layers contain two types of tetrahedral sites: T 1 (3-connected, i.e. having three O atoms shared by adjacent uranyl polyhedra) and T 2 (4-connected). The Se-for-S substitution in tetrahedral sites is highly selective with smaller S 6+ cation showing a strong preference for the more tightly bonded T 2 site. Crystallization in the pure Se system starts with the formation of Cs 2 [(UO 2 )(SeO 4 ) 2 (H 2 O)](H 2 O) crystals, its subsequent dissolution and formation of Cs 2 [(UO 2 ) 2 (SeO 4 ) 3 ]. The information-based structural complexity calculations for these two phases support the rule that more topologically complex structures form at the latest stages of crystallization. [ABSTRACT FROM AUTHOR]

Single crystals of seven novel uranyl oxysalts of selenium with protonated methylamine molecules, [C 2 H 8 N] 2 [(UO 2 )(SeO 4 ) 2 (H 2 O)] ( I ), [C 2 H 8 N] 2 [(UO 2 ) 2 (SeO 4 ) 3 (H 2 O)] ( II ), [C 4 H 15 N 3 ][H 3 O] 0.5 [(UO 2 ) 2 (SeO 4 ) 2.93 (SeO 3 ) 0.07 (H 2 O)](NO 3 ) 0.5 ( III ), [C 2 H 8 N] 3 [H 5 O 2 ][(UO 2 ) 2 (SeO 4 ) 3 (H 2 O) 2 ] 2 (H 2 O) 5 ( IV ), [C 2 H 8 N] 2 [H 3 O][(UO 2 ) 3 (SeO 4 ) 4 (HSeO 3 )(H 2 O)](H 2 SeO 3 ) 0.2 ( V ), [C 4 H 12 N] 3 [H 3 O][(UO 2 ) 3 (SeO 4 ) 5 (H 2 O)] ( VI ), and [C 2 H 8 N] 3 (C 2 H 7 N)[(UO 2 ) 3 (SeO 4 ) 4 (HSeO 3 )(H 2 O)] ( VII ) have been prepared by isothermal evaporation from aqueous solutions. Their crystal structures have been solved by direct methods and their uranyl selenate and selenite–selenate units investigated using black-and-white graphs from the viewpoints of topology of interpolyhedral linkages and isomeric variations. The crystal structure of IV is based upon complex layers with unique topology, which has not been observed previously in uranyl selenates. Investigations of the statistics and local distribution of the U–O br –Se bond angles demonstrates that shorter angles associate with undulations, whereas larger angles correspond to planar areas of the uranyl selenite layers. [ABSTRACT FROM AUTHOR]

Borophosphates of transition 3d metals are based on the mixed heteropolyhedral MTT - or MTTTr -type frameworks formed by M Ø 6 octahedra, two types of T Ø tetrahedra (PO 4 and BO 4 tetrahedra), and, more rarely, Tr O 3 triangles (BO 3 triangles). Family of compounds with the general formula A 1 − x + B x 2 + { M x 2 + M 1 − x 3 + [BP 2 O 8 (OH)]} (where A + ​= ​K, Rb, Cs, NH 4 , B 2+ = Ba, Pb, M 2+ ​= ​Fe, Co, Zn, and M 3+ ​= ​Al, Ga, V3+, Fe3+, Sc, In; x ​= ​0, 1) includes monoclinic (space group P 2 1 / c) and triclinic (space group P 1 ¯) borophosphates. Single crystals of Rb{V[BP 2 O 8 (OH)]} were synthesized by a hydrothermal method. The crystal structure was studied by single-crystal X-ray diffraction analysis: space group P 2 1 / c (No. 15), a ​= ​9.3699(8), b ​= ​8.3162(7), c ​= ​9.6707(8) Å, β ​= ​102.073(9); V ​= ​736.89(11) Å3. The crystal structure of Rb{V[BP 2 O 8 (OH)]} was refined to the final R ​= ​4.52%. A topological description of both structure types of the A 1 − x + B x 2 + { M x 2 + M 1 − x 3 + [BP 2 O 8 (OH)]} compounds and related vanadium-containing phases is given. Because these compounds are characterized by the microporous crystal structures, the possible migration paths for different alkaline ions have been calculated. Family of compounds with the general formula A 1 − x + B x 2 + { M x 2 + M 1 − x 3 + [BP 2 O 8 (OH)]} includes monoclinic (space group P 2 1 / c) and triclinic (space group P 1 ¯) borophosphates.A topological description of both structure types and related vanadium-containing phases is given.The possible migration paths for different alkaline ions have been calculated. [Display omitted] • A topological description of both structure types of the A 1 − x + B x 2 + { M x 2 + M 1 − x 3 + [BP 2 O 8 (OH)]} compounds and related vanadium-containing phases is given. • The possible migration paths for different alkaline ions have been calculated. [ABSTRACT FROM AUTHOR]