Cation-cation interaction in mixed-valent An(IV)/Np(V) tribromoacetates [An(NpO2)(H2O)3(CBr3COO)5]·CBr3COOH·nH2O,An = Th(IV), Np(IV)

The structure of new mixed-valent An(IV)/Np(V) compounds [An(NpO₂)(H₂O)₃(CBr₃COO)₅]·CBr₃COOH·nH₂O, where An(IV) = Th and Np, was studied. Two independent Np(V) atoms have the coordination surrounding in the form of pentagonal bipyramids with the O atoms of NpO ₂ ⁺ dioxocations in apical positions; the equatorial planes of the bipyramids are constituted by the O atoms of five CBr₃COO^? ions. Two independent An(IV) atoms have the oxygen surrounding in the form of distorted tricapped trigonal prisms (CN = 9) constituted by the O atoms of four CBr₃COO^? ions, two NpO ₂ ⁺ cations, and three water molecules. Eight of ten independent CBr₃COO^? anions link the An⁴⁺ and NpO ₂ ⁺ cations in the bidentate bridging fashion into electrically neutral chains [An(NpO₂)(H₂O)₃(CBr₃COO)₅]n, and two CBr₃COO^? anions interact with two independent NpO ₂ ⁺ dioxocations in the monodentate fashion. CBr₃COOH and water molecules are located between the layers. In the [An(NpO₂)(H₂O)₃(CBr₃COO)₅]n chains, NpO ₂ ⁺ cations alternate with An⁴⁺ cations, and mixed-valent An(IV)/Np(V) cation-cation interaction arises, in which each NpO ₂ ⁺ cation acts as a bidentate ligand and An⁴⁺ acts as coordination center for two dioxocations. [Th(NpO₂)(H₂O)₃(CBr₃COO)₅]·CBr₃COOH·2H₂O is the first example of a Th(IV) compound in which cation-cation bonds with the NpO ₂ ⁺ ions are present.     

Crystallization of salts M3[NpO4(OH)2]·nH2O (M = Na, K, Rb, Cs) from concentrated alkali solutions at low temperatures. Synthesis and structure of a new Np(VII) compound, Na3[NpO4(OH)2]·6H2O

Precipitation of salts M₃[NpO₄(OH)₂]·nH₂O (M = Na, K, Rb, Cs) from concentrated alkali solutions at low temperatures (about ?10°C) was studied. From solutions with [OH^?] > 9.5 M, these compounds are isolated as coarse black crystals in high yield without impurity of other phases. The K, Rb, and Cs salts crystallize in the form of the previously studied compounds K₃[NpO₄(OH)₂]·2H₂O and M₃[NpO₄(OH)₂]·3H₂O (M = Rb, Cs). In the case of Na, a new hydrate Na₃[NpO₄(OH)₂]·6H₂O was obtained, and its crystal structure was determined. Crystals of the hexahydrate consist of centrosymmetrical tetragonal-bipyramidal anions [NpO₄(OH)₂]^3?, crystallographically independent Na(1) and Na(2) cations, and water molecules. The coordination surrounding of the Np atom is characterized by noticeable difference (Δ = 0.0203 Å) in the Np-O bond lengths in the equatorial plane of the bipyramid. The [NpO₄(OH)₂]^3? anions are combined with the Na(2) cations to form infinite chains [Na(2)NpO₄(OH)₂(H₂O)₂]^2? in such a manner that the lateral edges of the anion are simultaneously the lateral edges of the Na(2) coordination polyhedron. Incorporation of one of the two crystallographically independent O atoms of the NpO₄ group into the Na(2) coordination surrounding is responsible for a noticeable difference in the Np-O bond lengths in the equator of the [NpO₄(OH)₂]^3? anion. The types of hydrogen bonding in the structures of Na3[NpO₄(OH)₂]·nH₂O (n = 0, 2, 4, 6) are compared.     

Crystal structure of a double Np(V) ammonium propionate, NH4[(NpO2)3(C2H5COO)4(H2O)]·3H2O

The structure of NH₄[(NpO₂)₃(C₂H₅COO)₄(H₂O)]·3H₂O was studied by single crystal X-ray diffraction. The single crystals were prepared by hydrothermal synthesis. In the structure, there are three crystallographically independent Np atoms with different equatorial surrounding. All of them have CN 7; the coordination polyhedron is a distorted pentagonal bipyramid. Each NpO ₂ ⁺ cation is bonded to four other cations, acting simultaneously as a bidentate ligand and a coordination center for two other dioxocations. The cation-cation interactions result in formation of trigonal-hexagonal cationic networks.     

Synthesis and crystal structure of a new Np(V) oxalate, Na4(NpO2)2(C2O4)3·6H2O

A new oxalate complex, Na₄(NpO₂)₂(C₂O₄)₃·6H₂O, with the Np:C₂O₄ ratio of 2:3 was synthesized and studied by single crystal X-ray diffraction. In the crystal, the NpO ₂ ⁺ cations and oxalate anions are bound in open networks [(NpO₂)₂(C₂O₄)₃] _n ^4n- parallel to the bc plane. The Na(1) cations are accommodated in large voids of the neptunyl oxalate networks with the formation of crimped mixed-cation layers of the composition [Na₂(NpO₂)₂(C₂O₄)₃] _n ^2n- . The negative charge of the layers is compensated by the Na(2) cations arranged between the layers. The Np atoms have a pentagonal bipyramidal coordination surrounding with the equatorial plane formed by the oxygen atoms of three oxalate anions. The structure contains tridentate-bridging and tetradentate-bridging oxalate anions.     

Crystal Structure of Neptunium(V) Phthalate (NpO2)2(OOC)2C6H4·4H2O

The crystal structure of (NpO₂)₂(OOC)₂C₆H₄·4H₂O [rhombic cell: a = 15.937(3), b = 26.922(5), c = 8.020(2) Å, space group Pbcn, Z = 8, V = 3441.0(12) ų, d _calc = 2.988 g cm^{- 3}, CAD4, MoK , graphite monochromator, 2934 independent reflections; R ₁ = 0.0352, wR ₂ = 0.0951] was studied. The structure consists of NpO₂ ⁺ cations, H₄C₆(COO)₂ ^{2 -} anions, and molecules of coordinated and crystallization water. The crystal lattice involves neutral layers [(NpO₂)₂(OOC)₂C₆H₄(H₂O)₃] _n parallel to the {101} plane. The dioxocations in these layers are bonded to each other to form cationic networks [the Np···Np distance is 3.911(1)-4.202(1) Å]. The coordination polyhedra of Np(1) and Np(2) are pentagonal bipyramids (CN 7). The point group of the neptunyl(V) groups is close to D _h. These groups are bidentate ligands in the cation-cation interaction. The Np = O bond lengths are 1.852(6) [Np(1)-O(1)], 1.849(7) [Np(1)-O(2)], 1.845(7) [Np(2)-O(3)], and 1.841(7) Å [Np(2)-O(4)]; the O = Np = O bond angles are 178.6(3)° [O(2)-Np(1)-O(1)] and 177.4(3)° [O(3)-Np(2)-O(4)]. The equatorial plane of the Np(1) bipyramid consists of two oxygen atoms of adjacent Np(2)O₂ ⁺ dioxocations, two water molecules, and a single oxygen atom of the phthalate anion. The equatorial plane of the Np(2) bipyramid consists of two oxygen atoms of adjacent Np(1)O₂ ⁺ dioxocations, two oxygen atom of the phthalate anion, and a single water molecule. The bond lengths in the equatorial plane of the bipyramid lie in the following ranges: Np-Oyl 2.373(7)-2.437(7) Å (average 2.397 Å) , Np-Ophth 2.360(7)-2.474(7) Å (average 2.431 Å), and Np-Owater 2.534(8)-2.558(9) Å (average 2.544 Å). The phthalate anions are tridentate bridging ligands binding neptunium atoms only within a single cationic network.     

Mixed-Cation Molybdate Complex of Neptunium(V), Li2Na[NpO2(MoO4)2]·4H2O

Radiochemistry - A new mixed-cation complex Li2Na[NpO2(MoO4)2]·4H2O with NpO2+ : MoO42– = 1 : 2 has been synthesized and structurally characterized. The coordination environment of Np(V)...     

Crystal Structure and Electronic Absorption Spectrum of Double Neptunium(V) Phthalate Co(NH3)6NpO2[(OOC)2C6H4]2·2H2O

Single crystals of Co(NH₃)₆NpO₂[(OOC)₂C₆H₄]₂·2H₂O were grown. The crystal structure of this compound [monoclinic cell: a = 7.748(2), b = 23.051(5), c = 14.608(3) Å, = 96.21(3)°, space group P2₁/c, Z = 4, V = 2593.7(9) ų, d _calc = 2.034 g cm^{- 3}, CAD4 automatic diffractometer, MoK , graphite monochromator, R ₁ = 0.041 for all 3567 reflections observed, wR ₂ = 0.1344 for all 4445 unique reflections, 325 refined parameters] was studied. The structure consists of infinite anionic chains {NpO₂[(OOC)₂C₆H₄]₂} _n ^{3 n -}, [Co(NH₃)₆]^{3 +} cations, and molecules of crystallization water. Neptunium(V) atom is in pentagonal-bipyramidal oxygen surrounding (CN 7); the neptunyl(V) group is linear and symmetrical; the Np = O bond lengths are 1.830(6) and 1.833(5)Å, the O = Np = O angle is 176.4(2)°. The equatorial plane of the bipyramid is formed by five oxygen atoms of phthalate anions. The Np-Oeq bond length correlates with the denticity of the phthalate anions. Two types of phthalate anions are localized in the structure. The first tridentate ligand is a bridge between Np(V) atoms in the chains. The second ligand is coordinated to Np in the bidentate fashion to form NpOCCCCO seven-membered chelate ring. The cation [Co(NH₃)₆]^{3 +} has an octahedral structure. The average Co-N distance in the octahedron is 1.961 Å the N-Co-N bond angles are close to 90°. Two water molecules along with [Co(NH₃)₆]^{3 +} cations are located between the anionic chains {NpO₂[(OOC)₂C₆H₄]₂} _n ^{3 n -}. The chains are additionally bonded along the Z-axis of the crystal by O_w-H···O hydrogen bonds.     

Synthesis and structure of actinide(VII) compounds Rb3NpO4(OH)2·3H2O and Rb3PuO4(OH)2·3H2O

Actinide(VII) salts Rb₃[NpO₄(OH)₂]·3H₂O (I) and Rb₃[PuO₄(OH)₂]·3H₂O (II) were prepared as single crystals and examined by X-ray diffraction. The compounds are isostructural and crystallize in the monoclinic system, space group C2/c, Z = 4; unit cell parameters: a = 12.1544(3), b = 10.9942(2), c = 7.789(2) ?, ?? = 91.0930(11)° for I and a = 12.1254(3), b = 10.9506(2), c = 7.7699(2) ?, ?? = 90.8253(12)° for II. The main structural elements of I and II are centrosymmetrical anions [AnO₄(OH)₂]^3? forming together with water molecules, owing to strong hydrogen bonding, chains oriented along [101]. In [AnO₄(OH)₂]^3? anions, the central An(VII) atom has a tetragonal-bipyramidal oxygen surrounding. The An-O(OH) interatomic distances decrease in going from I to II owing to actinide contraction by a factor of ??2 more strongly than the An-O bond lengths in the equatorial planes of the bipyramids. The previously studied structure of Cs₃[NpO₄(OH)₂]·3H₂O (III) was refined.     

Interaction of An(VI) (An = U, Np, Pu) and Np(V) with 2,3-pyridinedicarboxylic (quinolinic) acid (H2Quin): Complexation in aqueous solutions, synthesis and structure of the complexes [UO2(HQuin)2], [(NpO2)2(HQuin)2(C6H4NO3)2]·2H2O, and [PuO2Quin(H2O)]

Complexation of An(VI) (An = U, Np, Pu), and Np(V) with 2,3-pyridinedicarboxylic (quinolinic, H₂Quin) acid in aqueous solutions was studied. Np(V) can form 1: 1 and 1: 2 complexes, and An(VI), also 1: 3 complexes (at pH ? 6 and [H₂Quin] ? 0.1 M). Quinolinate ion can coordinate to actinide(VI) and (V) ions in solutions in different modes. The apparent stability constants of the complexes in a wide pH range and the concentration stability constants of the An(VI) complexes were measured. In the series from Pu(VI) to U(VI), the stability of the complexes slightly increases. Crystalline complexes [UO₂(HQuin)₂], [(NpO₂)₂(HQuin)₂(HL)₂]·2H₂O (HL is N-protonated 2-hydroxypyridine-3-carboxylic acid anion), and [PuO₂Quin(H₂O)] were synthesized, and their structures were determined by single crystal X-ray diffraction. Different types of coordination of quinolinate ions to actinide ions are also observed in the crystalline complexes.     

X-ray powder diffraction and IR study of NaMg(H2O)2[BP2O8]·H2O and NH4Mg(H2O)2[BP2O8]·H2O

NaMg(H₂O)₂[BP₂O₈]·H₂O was prepared by hydrothermal synthesis and was characterized by X-ray powder difraction and IR method. The title compound was synthesized from MgCl₂·6H₂O, NaBO₃·4H₂O, and (NH₄)₂HPO₄ with variable molar ratios using hydrothermal method by heating at 165 °C for 3 days. The X-ray powder diffraction data was indexed in hexagonal system, the unit cell parameters were found to be as a = 9.428, c = 15.82 Å, Z = 4 and the space group is P6₁22. It is isostructural with M^lM^ll(H₂O)[BP₂O₈] type compounds where M^l = Na, K; M^ll = Mg, Mn, Fe, Co, Ni and Zn. In addition NH₄Mg(H₂O)₂[BP₂O₈]·H₂O was also synthesized the first time in this research. Its unit cell parameters and hkl values were in good agreement with the sodium magnesium compound. The unit cell parameters are a = 9.529, c = 15.736 Å. The indexed X-ray powder diffraction data of both compounds which were not reported in the literature is presented in this work. The IR data of NaMg(H₂O)₂[BP₂O₈]·H₂O is also reported.     

Synthesis, Physicochemical Properties, and Electrode Behavior of Ni2[Ni(OH)6W6O18 ] · 8H2O

Nickel(II) hexatungstonickelate(II) was synthesized and characterized by elemental analysis, x-ray diffraction, thermal analysis, IR spectroscopy, and ¹H nuclear magnetic resonance. The results demonstrate that constitutional water is present in the form of OH groups, which can be removed by heating to 230–370°C. The chemical formula of the compound is Ni₂[Ni(OH)₆W₆O₁₈] · 8H₂O. Nickel(II) hexatungstonickelate(II), a poorly soluble compound, was tested as an electrode for Ni(II) determination in solution. Its electrode properties and selectivity for other ions suggest that it is a promising material for such applications. At pH 5, the ion-selective electrode we fabricated has a Nernstian response to Ni(II) (10^–5 to 10^–1 mol/l) which is close to that predicted theoretically.     

Complexes with substituted 2,5-dihydroxy-p-benzoquinones: The inclusion compounds [Y(H2O)3]2 (C6Cl2O4)3·6.6H2O and [Y(H2O)3]2 (C6Br2O4)3·6H2O

Single crystal of [Y(H₂O)₃]₂ (C₆Br₂O₄)₃·6H₂O and [Y(H₂O)₃]₂ (C₆Cl₂O₄)₃·6.6H₂O were grown in aqueous silicagel. The compounds are in principle isostructural. In Y chloranilate one additional water site is occupied as verified by X-ray single crystal structure analysis. Y³⁺ is nine-coordinated by three water molecules and six oxygen atoms of the bischelating (C₆X₂O₄)²⁻ ions (XCl, Br). The coordination polyhedron is an only slightly distorted tri-capped trigonal prism. The connection of Y³⁺ with the dianions leads to infinite, corrugated layers. The layer stacking yields cage-like cavities in which water molecules are accomodated. Hydrogen bonds interlink adjacent layers. Further hydrogen bonds involve the entrapped water molecules. DSC measurements indicated a complicated dehydration process which caused right at the start destruction of the single crystals.     

Synthesis and Study of Sr[HSiUO6]2·2H2O and Ba[HSiUO6]2·2H2O

Uranosilicates of the general formula M^{I I}[HSiUO₆]₂·2H₂O (M^{I I} = Sr, Ba) were prepared by hydrothermal synthesis. Previously unknown intermediate crystal hydrates were separated and studied by X-ray diffraction (XRD), IR spectroscopy, and thermal analysis. Polymorphic transitions -Sr[HSiUO₆]₂ -Sr[HSiUO₆]₂ and -Ba[HSiUO₆]₂ -Ba[HSiUO₆]₂ were revealed at 700 and 780°C, respectively.     

On the thermal decomposition of the zinc(II) hydroxide chlorides Zn5(OH)8Cl2·H2O and Β-Zn(OH)Cl

The thermal decomposition of Zn₅(OH)₈Cl₂·H₂O and -Zn(OH)Cl materials under several experimental conditions has been studied by thermal analysis, X-ray powder diffraction and X-ray high-temperature powder diffraction techniques. Several reaction schemes are proposed to account for thermal decomposition reactions undergone by both zinc hydroxide chlorides.     

Crystal and Molecular Structure of a New Complex of [60]Fullerene, 2(C60)·2(TMTSF)·(C6H6)

Abstract

A new molecular complex of [60]fullerene with composition 2(C₆₀)·2(TMTSF)·(C₆H₆) was synthesized. The structure and composition of the complex were found by an x-ray study. Crystal data: 2(C₆₀)2(C₁₀H₁₂Se₄)(C₆H₆), M = 2415.4, monoclinic, a = 19.388(4), b = 13.410(2), c = 32.467(6) A, β = 92.71(2)°, V = 8432(3) [Adot]³, space group P2₁/n, Z = 4, d_calc = 1.903 g/cm³, R = 0.0606. The crystal structure was shown to be layered with the alternating layers of three types. Two of them have the same composition (C₆₀, TMTSF) but different interorientation of molecules in a layer and different number of shortened contacts C…C and C…Se. The third layer consists of benzene molecules. The energy of intermolecular interactions C₆₀…. TMTSF was estimated by ab initio calculations. The TMTSF molecule has a “boat” conformation.     

Crystal Structure of An(VI) Complexes with Succinate Anions, [PuO2(C4H4O4)(H2O)] and Cs2[(AnO2)2(C4H4O4)3]·H2O (An = U,Np, Pu)

Radiochemistry - Actinide(VI) complexes with succinate anions [PuO2(succ)(H2O)] and Cs2[(AnO2)2(succ)3]·H2O (An = U, Np, Pu), where succ = [C4H4O4]2 ?, were synthesized and studied by...     

Cation–Cation Interaction in the Np(V) Complex with Cyclobutanecarboxylic Acid Anions,Na[NpO2(cbc)2]

Radiochemistry - The Np(V) complex Na[NpO2(cbc)2] was isolated in the crystalline form and studied by single crystal X-ray diffraction. The coordination surrounding of the Np(1) atom is a...     

Interaction of U(VI), Np(VI), Pu(VI), and Np(V) with benzenetricarboxylic acids: Complexation in aqueous solutions, synthesis, and crystal structure of uranyl complexes [UO2(H2O)2{C6H3(COO)2(COOH)}]2·2H2O and [(UO2)3(H2O)4{C6H3(COO)3}2]

The complexation of U(VI), Np(VI), and Pu(VI) and of Np(V) with 1,2,3- and 1,2,4-benzenetricarboxylic acids (BTC) in aqueous solutions was studied in wide ranges of pH and actinyl ion concentrations. The compositions of the forming hexavalent actinide complexes were determined. Their apparent stability constants β₁′ depend on pH of the solution: in the pH range 2–4, logβ₁′ from 2 to 4 for the complexes of U(VI), Np(VI), and Pu(VI) with 1,2,3-BTC and from 1.5 to 3.5 for the complexes with 1,2,4-BTC. For Np(V), the β₁′ values are close with both acids, and at equal pH values the Np(V) complexes are less stable than the An(VI) complexes (An = U, Np, Pu). With an increase in pH from ～3 to 6.2–6.9, logβ₁′ of the Np(V) complexes increases approximately from 0.5 to 3. Solid U(VI) complexes with 1,2,3- and 1,2,4-benzenetricarboxylic acids were synthesized by the hydrothermal method, their crystal structure was determined, and the IR spectra were examined.     

Synthesis and Study of Uranium-Containing Aluminum Compounds Al[BVUO6]2[OH]·nH2O (BV = P,As)

A procedure was developed for preparing aluminum hydroxouranophosphate and hydroxourano- arsenate. The structural features and thermal decomposition pathways of the compounds were studied by X-ray diffraction, IR spectroscopy, and thermal analysis.