A. G. Verevkin

Maximum Filling Principle and Sublattices of Actinide Atoms in Crystal Structures

The most important characteristics of the Voronoi-Dirichlet polyhedra (VDP) of A atoms (A is actinide) in chemically homogeneous sublattices in the crystal structures of 3479 inorganic, coordination, and organometallic compounds are determined. The effect of the actinide nature on the A-A interatomic distances in the crystal structures is considered. In the Th, U, Np, or Pu sublattices, VDP have most often 14 faces and the Fedorov cuboctahedron is the most abundant type of VDP, whereas in Ac, Pa, Am, Cm, Bk, or Cf sublattices, the VDP have mainly 12 faces and are shaped like rhomobododecahedra. In A sublattices that typically form VDP with 14 faces, the actinide atoms occupy, most often, sites with C1 symmetry (47 to 59% of the sample size). In the case of actinides whose A sublattices tend to form VDP with 12 faces, the C1 site symmetry is found either very rarely (Pa, Am, Cf) or not at all (Ac, Cm, Bk).

Neutron diffraction study of Rb2UO2(SeO4)2 · 2D2O

A powder of deuterated rubidium diselenatouranylate dihydrate Rb2UO2(SeO4)2 · 2D2O has been studied by neutron diffraction. The compound is orthorhombic, space group Pna21, with the following unit cell parameters: a = 13.654(2) Å, b = 11.863(2) Å, c = 7.625(1) Å, Z = 4, RF = 3.77, RI = 6.12, and χ2 = 2.21. Basic structure units are [UO2(SeO4)2 · D2O]2− layers belonging to the AB22M1 crystal-chemical group (A = UO22+, B2 = SeO42−, M1 = D2O) of uranyl complexes. The hydrogen atoms if the water molecules involved in the layer form intralayer hydrogen bonds with the terminal oxygen atoms of selenate ions. The outer-sphere water molecules are coordinated to the rubidium ions and are involved in hydrogen bonding with oxygen atoms of neighboring [UO2(SeO4)2 · D2O]2− layers.

X-ray diffraction study of Rb2[(UO2)2(CrO4)3(H2O)2] · 4H2O

The compound Rb2[(UO2)2(CrO4)3(H2O)2] · 4H2O was studied by X-ray diffraction. The crystals are monoclinic, a = 10.695(2) Å, b = 14.684(3) Å, c = 14.125(3) Å, β = 108.396(4)°, sp. gr. P21/c, Z = 4, V = 2104.9(7) Å3, and R = 0.0491. The main structural units are layers consisting of [(UO2)2(CrO4)3(H2O)2]2− anions belonging to the crystal-chemical group A2T23B2M21 (A = UL22+, T3 and B2 are CrO42−, and M1 is H2O) of uranyl complexes. The uranium-containing layered groups are held together by electrostatic interactions with rubidium cations, as well as by hydrogen bonds with the participation of inner- and outer-sphere water molecules.The compound Rb{sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}(H{sub 2}O){sub 2}] . 4H{sub 2}O was studied by X-ray diffraction. The crystals are monoclinic, a = 10.695(2) A, b = 14.684(3) A, c = 14.125(3) A, {beta} = 108.396(4){sup o}, sp. gr. P2{sub 1}/c, Z = 4, V = 2104.9(7) A{sup 3}, and R = 0.0491. The main structural units are layers consisting of [(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}(H{sub 2}O){sub 2}]{sup 2-} anions belonging to the crystal-chemical group A{sub 2}T{sub 2}{sup 3}B{sup 2}M{sub 2}{sup 1} (A = UL{sub 2}{sup 2+}, T{sup 3} and B{sup 2} are CrO{sub 4}{sup 2-}, and M{sup 1} is H{sub 2}O) of uranyl complexes. The uranium-containing layered groups are held together by electrostatic interactions with rubidium cations, as well as by hydrogen bonds with the participation of inner- and outer-sphere water molecules.

An X-ray diffraction study of Rb[UO2(SeO4)F]·H2O

An X-ray diffraction study of Rb[UO2(SeO4)F]·H2O (I) was performed. The compound crystallizes in the rhombic system with the following unit cell parameters: a = 8.4753(6), b = 13.5234(9), c = 13.5296(9) Å, space group Pnma, Z = 8, V = 1550.7(2) Å3; R = 0.0248. The principal structural units of crystals of I are [UO2(SeO4)F]− layers belonging to crystal-chemical group AT3M2 (A = UO22+, T3 = SeO42−, M2 = F−) of uranyl complexes. The uranium-containing layered units are combined via electrostatic interaction with Rb cations and via a system of hydrogen bonds involving outer-sphere water molecules.

Synthesis and structure of Cs[UO2(SeO4)(OH)] · nH2O (n = 1.5 or 1)

The synthesis and single-crystal X-ray diffraction study of Cs[UO2(SeO4)(OH)] · 1.5H2O (I) and Cs[UO2(SeO4)(OH)] · H2O (II) are performed. Compound I crystallizes in the monoclinic crystal system, a = 7.2142(2) Å, b = 14.4942(4) Å, c = 8.9270(3) Å, β = 112.706(1)°, space group P21/m, Z = 4, and R = 0.0222. Compound II is monoclinic, a = 8.4549(2) Å, b = 11.5358(3) Å, c = 9.5565(2) Å, β = 113.273(1)°, space group P21/c, Z = 4, and R = 0.0219. The main structural units of crystals I and II are [UO2(SeO4)(OH)]− layers which belong to the AT3M2 crystal chemical group of uranyl complexes (A = UO22+, T3 = SeO42−, and M2 = OH−). In structure I, johannite-like layers are found. Structure II is a topological isomer of I. The two structures differ in the number of U(VI) atoms bound to the central atom by all bridging ligands.

X-ray diffraction study of Rb{sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}(H{sub 2}O){sub 2}] . 4H{sub 2}O

The compound Rb2[(UO2)2(CrO4)3(H2O)2] · 4H2O was studied by X-ray diffraction. The crystals are monoclinic, a = 10.695(2) Å, b = 14.684(3) Å, c = 14.125(3) Å, β = 108.396(4)°, sp. gr. P21/c, Z = 4, V = 2104.9(7) Å3, and R = 0.0491. The main structural units are layers consisting of [(UO2)2(CrO4)3(H2O)2]2− anions belonging to the crystal-chemical group A2T23B2M21 (A = UL22+, T3 and B2 are CrO42−, and M1 is H2O) of uranyl complexes. The uranium-containing layered groups are held together by electrostatic interactions with rubidium cations, as well as by hydrogen bonds with the participation of inner- and outer-sphere water molecules.The compound Rb{sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}(H{sub 2}O){sub 2}] . 4H{sub 2}O was studied by X-ray diffraction. The crystals are monoclinic, a = 10.695(2) A, b = 14.684(3) A, c = 14.125(3) A, {beta} = 108.396(4){sup o}, sp. gr. P2{sub 1}/c, Z = 4, V = 2104.9(7) A{sup 3}, and R = 0.0491. The main structural units are layers consisting of [(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}(H{sub 2}O){sub 2}]{sup 2-} anions belonging to the crystal-chemical group A{sub 2}T{sub 2}{sup 3}B{sup 2}M{sub 2}{sup 1} (A = UL{sub 2}{sup 2+}, T{sup 3} and B{sup 2} are CrO{sub 4}{sup 2-}, and M{sup 1} is H{sub 2}O) of uranyl complexes. The uranium-containing layered groups are held together by electrostatic interactions with rubidium cations, as well as by hydrogen bonds with the participation of inner- and outer-sphere water molecules.

Synthesis and X-ray structural investigation of (C{sub 3}N{sub 6}H{sub 7}){sub 4}(CN{sub 3}H{sub 6}){sub 2}[UO{sub 2}(CrO{sub 4}){sub 4}] . 4H{sub 2}O and (H{sub 3}O){sub 6}[UO{sub 2}(CrO{sub 4}){sub 4}]

AbstractSingle crystals of the compounds (C3N6 H7)4(CN3H6)2[UO2(CrO4)4] · 4H2O (I) and (H3O)6[UO2(CrO4)4] (II) are synthesized, and their structures are investigated using X-ray diffraction. Compound I crystallizes in the triclinic system with the unit cell parameters a = 6.3951(8) Å, b = 10.8187(16) Å, c = 16.9709(18) Å, α = 93.674(4)°, β = 97.127(4)°, γ = 92.020(4)°, space group, P

Synthesis and X-ray structural investigation of K{sub 8}[(UO{sub 2}){sub 2}(C{sub 2}O{sub 4}){sub 2}(SeO{sub 4}){sub 4}] . 2H{sub 2}O

\bar 1