V. N. Serezhkin

Some features of stereochemistry of U(VI)

Publisher Summary This chapter proposes a method of quantitative estimation of electron-donor ability of ligands that is based upon principally new geometric model of crystal structures. Within this model, the atoms are considered as deformable spheres of the fixed volume and the whole structure as a closest three-dimensional packing of these atoms. This packing is equivalent to the Voronoi-Dirichlet partition. The model is in agreement with the existing experimental data and classical concepts of the complex formation in uranyl-based systems. In addition, the model provides a unique framework for the interpretation of the experimental facts. The power of the proposed model and its predictive ability is most likely due to the fact that the 3-dimensional image of chemical bonds in crystals has many advantages over the classic 1-dimensional description.

X-Ray diffraction and IR-spectroscopic studies of UO2(n-C3H7COO)2(H2O)2 and Mg(H2O)6[UO2(n-C3H7COO)3]2

Single crystals of UO2(n-C3H7COO)2(H2O)2 (I) and Mg(H2O)6[UO2(n-C3H7COO)3]2 (II) are synthesized. Their IR-spectroscopic and X-ray diffraction studies are performed. Crystals I are monoclinic, a = 9.8124(7) Å, b = 19.2394(14) Å, c = 12.9251(11) Å, β = 122.423(1)°, space group P21/c, Z = 6, and R = 0.0268. Crystals II are cubic, a = 15.6935(6) Å, space group

Synthesis and crystal structure of [UO{sub 2}CrO{sub 4}(C{sub 5}NH{sub 5}COO){sub 2}(H{sub 2}O)]{center_dot}2H{sub 2}O

Pabar 3

Synthesis and X-ray diffraction study of (Cs{sub 0.5}Ba{sub 0.25})[UO{sub 2}(CH{sub 3}COO){sub 3}] and Ba{sub 0.5}[UO{sub 2}(CH{sub 3}COO){sub 3}]

, Z = 4, and R = 0.0173. The main structural units of I and II are [UO2(C3H7COO)2(H2O)2] molecules and [UO2(C3H7COO)3]− anionic complexes, respectively, which belong to AB201M21 (I) and AB301 (II) crystal chemical groups of uranyl complexes (A = UO22+, B01 = C3H7COO−, and M1 = H2O). A crystal chemical analysis of UO2L2 · nH2O compounds, where L is a carboxylate ion, is performed.

Crystal structure of PbUO{sub 2}(CH{sub 3}COO){sub 4}(H{sub 2}O){sub 3}

Crystals of UO{sub 2}CrO{sub 4}(C{sub 5}NH{sub 5}COO){sub 2}(H{sub 2}O)] {center_dot} 2H{sub 2}O are synthesized and their structure is studied by X-ray diffraction. The compound crystallizes in the triclinic crystal system. The unit cell parameters are as follows: a = 7.0834(10) Angstrom-Sign , b = 10.6358(14) Angstrom-Sign , c = 12.9539(17) Angstrom-Sign , {alpha} = 75.096(2) Degree-Sign , {beta} = 74.490(2) Degree-Sign , and {gamma} = 80.657(2) Degree-Sign ; V = 904.1(2) Angstrom-Sign {sup 3}, space group P1-bar, Z = 2, and R = 0.026. The structure is built of [UO{sub 2}CrO{sub 4}(C{sub 5}NH{sub 5}COO){sub 2}(H{sub 2}O)]{sub 2} centrosymmetric dimers, which are linked into a framework by a system of hydrogen bonds involving inner-sphere and outer-sphere water molecules. The coordination number of the U(VI) atom is seven, and the coordination polyhedron is a pentagonal bipyramid with the oxygen atoms of the uranyl group, two chromate groups, two molecules of isonicotinic acid, and a water molecule at the vertices. The crystal chemical formula of the [UO{sub 2}CrO{sub 4}(C{sub 5}NH{sub 5}COO){sub 2}(H{sub 2}O)]{sub 2} dimer is represented as AB{sup 2}M{sub 3}{sup 1}, where AB{sup 2}M{sub 3}{sup 1}, where A = UO{sub 2}{sup 2+}, B{sup 2} = CrO{sub 4}{sup 2-}, and M{sup 1} =morexa0» = C{sub 5}NH{sub 4}COOH and H{sub 2}O.«xa0lessAbstractCrystals of UO2CrO4(C5NH5COO)2(H2O)] · 2H2O are synthesized and their structure is studied by X-ray diffraction. The compound crystallizes in the triclinic crystal system. The unit cell parameters are as follows: a = 7.0834(10) Å, b = 10.6358(14) Å, c = 12.9539(17) Å, α = 75.096(2)°, β = 74.490(2)°, and γ = 80.657(2)°; V = 904.1(2) Å3, space group P

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

nbar 1n

Analysis of nonvalent interactions in the crystals of conformational polymorphs of the composition CaHbNcOdSe by means of molecular voronoi-dirichlet polyhedra

, Z = 2, and R = 0.026. The structure is built of [UO2CrO4(C5NH5COO)2(H2O)]2 centrosymmetric dimers, which are linked into a framework by a system of hydrogen bonds involving inner-sphere and outer-sphere water molecules. The coordination number of the U(VI) atom is seven, and the coordination polyhedron is a pentagonal bipyramid with the oxygen atoms of the uranyl group, two chromate groups, two molecules of isonicotinic acid, and a water molecule at the vertices. The crystal chemical formula of the [UO2CrO4(C5NH5COO)2(H2O)]2 dimer is represented as AB2M31, where AB2M31, where A = UO22+, B2 = CrO42−, and M1 = = C5NH4COOH and H2O.

Synthesis and crystal structure of [UO2CrO4(C5NH5COO)] · 0.25H2O

Uranyl triacetate complexes (Cs{sub 0.5}Ba{sub 0.25})[UO{sub 2}(CH{sub 3}COO){sub 3}] (I) and Ba{sub 0.5}[UO{sub 2}(CH{sub 3}COO){sub 3}] (II) are synthesized for the first time and their structures are determined by X-ray diffraction. Both compounds crystallize in the cubic crystal system. The crystal data are as follows: a = 17.3289(7) Angstrom-Sign , V = 5203.7(4) Angstrom-Sign {sup 3}, space group I2{sub 1}3 and Z = 16 (I); a = 17.0515(8) Angstrom-Sign , V = 4957.8(4) Angstrom-Sign {sup 3}, space group I 4 bar 3d, and Z = 16 (II). In I and II, as in all uranyl triacetates studied earlier, the coordination polyhedron of the uranium atom is a hexagonal bipyramid whose vertices are occupied by the oxygen atoms of the uranyl and three acetate groups. The uranium-containing group belongs to the AB{sub 3}{sup 01} (A = UO{sub 2}{sup 2+}, B{sup 01} = CH{sub 3}COO{sup -}) crystal chemical group of uranyl complexes. It was found that compound II is isostructural to the (Rb{sub 0.50}Ba{sub 0.25})[UO{sub 2}(CH{sub 3}COO){sub 3}] studied earlier.AbstractUranyl triacetate complexes (Cs0.5Ba0.25)[UO2(CH3COO)3] (I) and Ba0.5[UO2(CH3COO)3] (II) are synthesized for the first time and their structures are determined by X-ray diffraction. Both compounds crystallize in the cubic crystal system. The crystal data are as follows: a = 17.3289(7) Å, V = 5203.7(4) Å3, space group I213 and Z = 16 (I); a = 17.0515(8)Å, V = 4957.8(4) Å3, space group I