Hydrothermal synthesis of (C6N2H14)2(UVI2UIVO4F12), a mixed-valent one-dimensional uranium oxyfluoride

A new hybrid organic-inorganic mixed-valent uranium oxyfluoride, (C6N2H14)2(U3O4F12), UFO-17, has been synthesized under hydrothermal conditions using uranium dioxide as the uranium source, hydrofluoric acid as mineralizer, and 1,4-diazabicyclo[2.2.2]octane as template. The single-crystal X-ray structure was determined. Crystals of UFO-17 belonged to the orthorhombic space group Cmcm (no. 63), with a = 14.2660(15) A, b = 24.5130(10) A, c = 7.201(2) A, and Z = 4. The structure reveals parallel uranium-containing chains of two types: one type is composed of edge-sharing UO2F5 units; the other has a backbone of edge-sharing UF8 units, each sharing an edge with a pendant UO2F5 unit. Bond-valence calculations suggest the UF8 groups contain UIV, while the UO2F5 groups contain UVI. EXAFS data give results consistent with the single-crystal X-ray structure determination, while comparison of the uranium LIII-edge XANES of UFO-17 with that of related UIV and UVI compounds supports the oxidation-state assignment. Variable-temperature magnetic susceptibility measurements on UFO-17 and a range of related hybrid organic-inorganic uranium(IV) and uranium(VI) fluorides and oxyfluorides further support the formulation of UFO-17 as a mixed-valent UIV/UVI compound.     

Organically templated uranium(IV) fluorooxalates with layer structures: (H4TREN)[U2F6(C2O4)3].4H2O (TREN = tris(2-aminoethyl)amine) and (H4APPIP)[U2F6(C2O4)3].4H2O (APPIP = 1,4-bis(3-amino-propyl)piperazine)

Two organically-templated layered uranium(IV) fluorooxalates, (H(4)TREN)[U(2)F(6)(C(2)O(4))(3)].4H(2)O (1) (TREN = tris(2-aminoethyl)amine) and (H(4)APPIP)[U(2)F(6)(C(2)O(4))(3)].4H(2)O (2) (APPIP = 1,4-bis(3-aminopropyl)piperazine), have been synthesized by hydrothermal methods and structurally characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic susceptibility. Both structures consist of anionic [U(2)F(6)(C(2)O(4))(3)](4-) layers separated by organic ammonium cations and lattice water molecules. The UF(3)O(6) polyhedra are connected by oxalate ligands in different ways within the layers. They are the first examples of organically-templated uranium fluorooxalates. Crystal data for compound 1 follow: monoclinic, P2(1)/c (No. 14), a = 19.1563(5) A, b = 8.9531(2) A, c = 16.6221(4) A, beta = 114.633(1) degrees, and Z = 4. Crystal data for compound are the same as those for 1 except a = 10.3309(8) A, b = 15.564(1) A, c = 17.537(1) A, and beta = 95.430(4) degrees.     

UF3(H2O)(C2O4)0.5: a fluorooxalate of tetravalent uranium with a three-dimensional framework structure

A new uranium(IV) fluorooxalate, UF3(H2O)(C2O4)0.5, has been synthesized by a hydrothermal method and structurally characterized by single-crystal X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. The structure consists of two-dimensional layers of corner- and edge-sharing tricapped trigonal prisms with the composition UF(4/2)F(2/2)O3 linked by bisbidentate oxalate ligands to form a three-dimensional framework. Magnetic susceptibilities were measured to confirm the tetravalent state of uranium. Crystal data: monoclinic, space group C2/c, a = 17.246(3) Angstroms, b = 6.088(1) Angstroms, c = 8.589(2) Angstroms, beta = 95.43(3) degrees, and Z = 8.     

Hydrothermal preparation of nickel(II)/uranium(IV) fluorides with one-, two-, and three-dimensional topologies

A modified compositional diagram for the reactions of Ni(C(2)H(3)O(2))(2).4H(2)O with UO(2)(C(2)H(3)O(2))(2).2H(2)O and HF in aqueous media under mild hydrothermal conditions (200 degrees C) has been completed to yield three Ni(II)/U(IV) fluorides, Ni(H(2)O)(4)UF(6).1.5H(2)O (1), Ni(2)(H(2)O)(6)U(3)F(16).3H(2)O (2), and Ni(H(2)O)(2)UF(6)(H(2)O) (3). The structure of 1 consists of one-dimensional columns constructed from two parallel chains of edge-sharing dodecahedral [UF(8)] units. The sides of the columns are terminated by octahedral Ni(II) units that occur as cis-[Ni(H(2)O)(4)F(2)] polyhedra. In contrast, the crystal structure of 2 reveals a two-dimensional Ni(II)/U(IV) architecture built from edge-sharing tricapped trigonal prismatic [UF(9)] units. The top and bottom of the sheets are capped by fac-[Ni(H(2)O)(3)F(3)] octahedra. The structure of 3 is formed from [UF(8)(H(2)O)] tricapped trigonal prisms that edge share with one another to form one-dimensional chains. These chains are then joined together into a three-dimensional network by corner sharing with trans-[Ni(H(2)O)(2)F(4)] octahedra. Crystallographic data: 1, orthorhombic, space group Cmcm, a = 14.3383(8) A, b = 15.6867(8) A, c = 8.0282(4) A, Z = 8; 2, hexagonal, space group P6(3)/mmc, a = 7.9863(5) A, c = 16.566(1) A, Z = 2; 3, monoclinic, space group C2/c, a = 12.059(1) A, b = 6.8895(6) A, c = 7.9351(7) A, beta = 92.833(2) degrees, Z = 4.     

Structural influences of organonitrogen ligands on vanadium oxide solids. Hydrothermal syntheses and structures of the terpyridine vanadates [V2O4(terpy)2]3[V10O28], [VO2(terpy)][V4O10], and [V9O22(terpy)3

Hydrothermal reactions of the V2O5/2,2':6':2"-terpyridine/ZnO/H2O system under a variety of conditions yielded the organic-inorganic hybrid materials [V2O4(terpy)2]3[V10O28].2H2O (VOXI-10), [VO2(terpy)][V4O10] (VOXI-11), and [V9O22(terpy)3] (VOXI-12). The structure of VOXI-10 consists of discrete binuclear cations [V2O4(terpy)2]2+ and one-dimensional chains [V10O28]6-, constructed of cyclic [V4O12]4- clusters linked through (VO4) tetrahedra. In contrast, the structure of VOXI-11 exhibits discrete mononuclear cations [VO2(terpy)]1+ and a two-dimensional vanadium oxide network, [V4O10]1-. The structure of the oxide layer is constructed from ribbons of edge-sharing square pyramids; adjacent ribbons are connected through corner-sharing interactions into the two-dimensional architecture. VOXI-12 is also a network structure; however, in this case the terpy ligand is incorporated into the two-dimensional oxide network whose unique structure is constructed from cyclic [V6O18]6- clusters and linear (V3O5(terpy)3) moieties of corner-sharing vanadium octahedra. The rings form chains through corner-sharing linkages; adjacent chains are connected through the trinuclear units. Crystal data: VOXI-10, C90H70N18O42V16, triclinic P1, a = 12.2071(7) A, b = 13.8855(8) A, 16.9832(10) A, alpha = 69.584(1) degrees, beta = 71.204(1) degrees, gamma = 84.640(1) degrees, Z = 1; VOXI-11, C15H11N3O12V5, monoclinic, P2(1)/n, a = 7.7771(1) A, b = 10.3595(2) A, c = 25.715(4) A, beta = 92.286(1) degrees, Z = 4; VOXI-12, C45H33N9O22V9, monoclinic C2/c, a = 23.774(2) A, b = 9.4309(6) A, c = 25.380(2) A, beta = 112.047(1) degrees, Z = 4.     

One-dimensional array of two- and three-center cation-cation bonds in the structure of Li4[(UO2)10O10(Mo2O8)

Dark-red crystals of the new compound Li(4)[(UO(2))(10)O10(Mo(2)O(8))] (1) have been obtained by high-temperature solid-state reactions. The structure of 1 (monoclinic, P2(1)/c, a = 7.9426(4) A, b = 19.9895(9) A, c = 10.0796(5) A, beta = 90.575(2) degrees, V = 1600.24(13) A(3), Z = 4) consists of a framework of U and Mo polyhedra with Li+ cations in the channels. The framework contains seven-polyhedra-wide uranium oxide tapes interlinked by dimers of edge-sharing [4 + 1]-distorted MoO(5) polyhedra. The U-O tapes are parallel to the a axis, and their planes are oriented parallel to (021) and (02) so that they are cross-linked within the framework. The core of the tapes consists of unprecedented one-dimensional arrays of cation-cation-bonded uranyl ions. The arrays are constructed from eight-membered cycles with uranyl ions linked through two- and three-center cation-cation interactions.     

Cation-cation interactions in Sr5(UO2)20(UO6)2O16(OH)6(H2O)6 and Cs(UO2)9U3O16(OH)5

Two novel U6+ compounds, Sr5(UO2)20(UO6)2O16(OH)6(H2O)6 (SrFm) and Cs(UO2)9U3O16(OH)5 (CsFm), have been synthesized by mild hydrothermal reactions. The structures of SrFm (orthorhombic, C2221, a = 11.668(1), b = 21.065 (3), c = 13.273 A, V = 3532.5(1) A3, Z = 2) and CsFm (trigonal, R3c, a = 11.395(2), c = 43.722(7) A, V = 4916.7(1) A3, Z = 6) are rare examples of uranyl compounds that contain cation-cation interactions where an O atom of one uranyl ion is directly linked to another uranyl ion. Both structures are complex frameworks. SrFm contains sheets of polyhedra that are linked through cation-cation interactions with uranyl ions located between the sheets. CsFm possesses an unusually complex framework of vertex- and edge-sharing U6+ polyhedra that incorporates cation-cation interactions.     

(CH3)4N][(C5H5NH)0.8((CH3)3NH)0.2]U2Si9O23F4 (USH-8): an organically templated open-framework uranium silicate

The open-framework uranium fluorosilicate [(CH3)4N][(C5H5NH)0.8((CH3)3NH)0.2]U2Si9O23F4 (USH-8) has been synthesized hydrothermally by using tetramethylammonium hydroxide and pyridine-HF. The compound has a framework composition U2Si9O23F4 based on silicate double layers that are linked by chains of UO3F4 pentagonal bipyramids. The framework has 12-ring channels along [010] and 7-ring channels along [100]. The [010] 12-ring channels have a calabash-shape with the middle part partially blocked by the uranyl oxygen atoms. The narrow side of the 12-ring channels is occupied by well-ordered TMA cations while the wide side is occupied by disordered pyridinium and trimethylammonium cations.     

Synthesis, crystal structure and optical properties of [Ag(UO2)3(OAc)9][Zn(H2O)4(CH3CH2OH)2]: a novel compound containing closed-shell 3d10, 4d10 and 5d10 metal ions

[Ag(UO(2))(3) (OAc)(9)][Zn(H(2)O)(4)(CH(3)CH(2)OH)(2)] (, OAc = CH(3)COO(-)) crystallized from an ethanol solution and its structure was determined by IR spectroscopy, elemental analysis, (1)H NMR, (13)C NMR and X-ray crystallography; it is composed of [Zn(H(2)O)(4)(CH(3)CH(2)OH)(2)](2+) cations and [Ag(UO(2))(3)(OAc)(9)](2-) anions in which triuranyl [(UO(2))(OAc)(3)](3) clusters are linked by the Ag ion.     

Reactions of acetonitrile coordinated to a nitrosylruthenium complex with H2O or CH(3)OH under mild conditions: structural characterization of imido-type complexes

The reaction of cis-[Ru(NO)(CH(3)CN)(bpy)(2)](3+) (bpy = 2,2'-bipyridine) in H(2)O at room temperature proceeded to afford two new nitrosylruthenium complexes. These complexes have been identified as nitrosylruthenium complexes containing the N-bound methylcarboxyimidato ligand, cis-[Ru(NO)(NH=C(O)CH(3))(bpy)(2)](2+), and methylcarboxyimido acid ligand, cis-[Ru(NO)(NH=C(OH)CH(3))(bpy)(2)](3+), formed by an electrophilic reaction at the nitrile carbon of the acetonitrile coordinated to the ruthenium ion. The X-ray structure analysis on a single crystal obtained from CH(3)CN-H(2)O solution of cis-[Ru(NO)(NH=C(O)CH(3))(bpy)(2)](PF(6))(3) has been performed: C(22)H(20.5)N(6)O(2)P(2.5)F(15)Ru, orthorhombic, Pccn, a = 15.966(1) A, b = 31.839(1) A, c = 11.707(1) A, V = 5950.8(4) A(3), and Z = 8. The structural results revealed that the single crystal consisted of 1:1 mixture of cis-[Ru(NO)(NH=C(O)CH(3))(bpy)(2)](2+) and cis-[Ru(NO)(NH=C(OH)CH(3))(bpy)(2)](3+) and the structural formula of this single crystal was thus [Ru(NO)(NH=C(OH(0.5))CH(3))(bpy)(2)](PF(6))(2.5). The reaction of cis-[Ru(NO)(CH(3)CN)(bpy)(2)](3+) in dry CH(3)OH-CH(3)CN at room temperature afforded a nitrosylruthenium complex containing the methyl methylcarboxyimidate ligand, cis-[Ru(NO)(NH=C(OCH(3))CH(3))(bpy)(2)](3+). The structure has been determined by X-ray structure analysis: C(25)H(29)N(8)O(18)Cl(3)Ru, monoclinic, P2(1)/c, a = 13.129(1) A, b = 17.053(1) A, c = 15.711(1) A, beta = 90.876(5) degrees, V = 3517.3(4) A(3), and Z = 4.     

Synthesis, structure, and infrared spectroscopy of the first Np5+ neptunyl silicates, Li6(NpO2)4(H2Si2O7)(HSiO4)2(H2O)4 and K3(NpO2)3(Si2O7)

Two Np(5+) silicates, Li(6)(NpO(2))(4)(H(2)Si(2)O(7))(HSiO(4))(2)(H(2)O)(4) (LiNpSi1) and K(3)(NpO(2))(3)(SiO(3)OH)(2) (KNpSi1), were synthesized by hydrothermal methods. The crystal structures were determined using direct methods and refined on the basis of F(2) for all unique data collected with Mo Kalpha radation and an APEX II CCD detector. LiNpSi1 crystallizes in orthorhombic space group Pnma with a =13.189(6) A, b = 7.917(3) A, c = 10.708(5) A, V = 1118.1(8) A3, and Z = 2. KNpSi1 is hexagonal, P62m, a = 9.734(1) A, c = 3.8817(7) A, V = 318.50(8) A3, and Z = 1. LiNpSi1 contains chains of edge-sharing neptunyl pentagonal bipyramids linked into two-dimensional sheets through direct linkages between the neptunyl polyhedra and the vertex sharing of the silicate tetrahedra. The structure contains both sorosilicate and nesosilicate units, resulting in a new complex neptunyl silicate sheet. KNpSi1 contains edge-sharing neptunyl square bipyramids linked into a framework structure through the sharing of vertices with the silicate tetrahedra. The neptunyl silicate framework contains channels approximately 6.0 A in diameter. These structures exhibit significant departures from other reported Np(5+) and U(6+) compounds and represent the first reported Np(5+) silicate structures.     

Novel acetate binding modes in [Na2Cu(CH3COO)4(H2O)].H2O

A new copper(II) acetate, [Na(2)Cu(CH(3)COO)(4)(H(2)O)].H(2)O (1), has been crystallized from an aqueous solution containing sodium acetate and copper(II) acetate monohydrate in a 4:1 ratio and the structure determined by X-ray crystallography. 1 crystallizes in the monoclinic space group P2(1)/c, with a = 16.638(3) A, b = 11.781(2) A, c = 15.668(3) A, beta = 90.11(3) degrees, V = 3071.0(11) A(3), and Z = 4. In the asymmetric unit, sodium ions bridge two crystallographically unique square planar [Cu(CH(3)COO)(4)](2-) units to their symmetry-generated neighbors to form corrugated 2D sheets of Na(2)Cu(CH(3)COO)(4), which are held together by H-bonding interactions involving the waters of crystallization. In contrast, the structures of known sodium copper acetates are better described as 3D frameworks. The metal centers are bridged by a number of acetates in novel coordination modes. The square planar Cu(II) geometry generated by oxygen atoms from four different acetates is an unexpected feature given the weak ligand field provided by the acetate ligands.     

Structural polarity induced by cooperative hydrogen bonding and lone-pair alignment in the molecular uranyl iodate Na2[UO2(IO3)4(H2O)

Na2[UO2(IO3)4(H2O)] has been synthesized under mild hydrothermal conditions. Its structure consists of Na+ cations and [UO2(IO3)4(H2O)](2-) anions. The [UO2(IO3)4(H2O)](2-) anions are formed from the coordination of a nearly linear uranyl, UO2(2+), cation by four monodentate IO(3-) anions and a coordinating water molecule to yield a pentagonal bipyramidal environment around the uranium center. The water molecules form intermolecular hydrogen bonds with the terminal oxo atoms of neighboring [UO2(IO3)4(H2O)](2-) anions to yield one-dimensional chains that extend down the b axis. There are two crystallographically unique iodate anions in the structure of Na2[UO2(IO3)4(H2O)]. One of these anions is aligned so that the lone-pair of electrons is also directed along the b axis. The overall structure is therefore polar, owing to the cooperative alignment of both the hydrogen bonds and the lone-pair of electrons on iodate. The polarity of the monoclinic space group C2 (a = 11.3810(12) A, b = 8.0547(8) A, c = 7.6515(8) A, beta = 90.102(2) degrees , Z = 2, T = 193 K) found for this compound is consistent with the structure. Second-harmonic generation of 532 nm light from a 1064 nm laser source yields a response of approximately 16x alpha-SiO2.     

Expanding the remarkable structural diversity of uranyl tellurites: hydrothermal preparation and structures of K[UO(2)Te(2)O(5)(OH)], Tl(3)[(UO(2))(2)[Te(2)O(5)(OH)](Te(2)O(6))].2H(2)O,beta-Tl(2)[UO(2)(TeO(3))(2)], and Sr(3)[UO(2)(TeO(3))(2)](TeO(3))(2)

The reactions of UO(2)(C(2)H(3)O(2))(2).2H(2)O with K(2)TeO(3).H(2)O, Na(2)TeO(3) and TlCl, or Na(2)TeO(3) and Sr(OH)(2).8H(2)O under mild hydrothermal conditions yield K[UO(2)Te(2)O(5)(OH)] (1), Tl(3)[(UO(2))(2)[Te(2)O(5)(OH)](Te(2)O(6))].2H(2)O (2) and beta-Tl(2)[UO(2)(TeO(3))(2)] (3), or Sr(3)[UO(2)(TeO(3))(2)](TeO(3))(2) (4), respectively. The structure of 1 consists of tetragonal bipyramidal U(VI) centers that are bound by terminal oxo groups and tellurite anions. These UO(6) units span between one-dimensional chains of corner-sharing, square pyramidal TeO(4) polyhedra to create two-dimensional layers. Alternating corner-shared oxygen atoms in the tellurium oxide chains are protonated to create short/long bonding patterns. The one-dimensional chains of corner-sharing TeO(4) units found in 1 are also present in 2. However, in 2 there are two distinct chains present, one where alternating corner-shared oxygen atoms are protonated, and one where the chains are unprotonated. The uranyl moieties in 2 are bound by five oxygen atoms from the tellurite chains to create seven-coordinate pentagonal bipyramidal U(VI). The structures of 3 and 4 both contain one-dimensional [UO(2)(TeO(3))(2)](2-) chains constructed from tetragonal bipyramidal U(VI) centers that are bridged by tellurite anions. The chains differ between 3 and 4 in that all of the pyramidal tellurite anions in 3 have the same orientation, whereas the tellurite anions in 4 have opposite orientations on each side of the chain. In 4, there are also additional isolated TeO(3)(2-) anions present. Crystallographic data: 1, orthorhombic, space group Cmcm, a = 7.9993(5) A, b = 8.7416(6) A, c = 11.4413(8) A, Z = 4; 2, orthorhombic, space group Pbam, a = 10.0623(8) A, b = 23.024(2) A, c = 7.9389(6) A, Z = 4; 3, monoclinic, space group P2(1)/n, a = 5.4766(4) A, b = 8.2348(6) A, c = 20.849(3) A, beta = 92.329(1) degrees, Z = 4; 4, monoclinic, space group C2/c, a = 20.546(1) A, b = 5.6571(3) A, c = 13.0979(8) A, beta = 94.416(1) degrees, Z = 4.     

Hydrothermal synthesis and characterization of [(UO2)2F8(H2O)2Zn2(4,4'-bpy)2].(4,4'-bpy), a mixed-metal uranyl aquofluoride with a pillared layer structure

A mixed-metal uranyl aquofluoride, [(UO2)2F8(H2O)2Zn2(4,4'-bpy)2].(4,4'-bpy), has been synthesized under hydrothermal conditions and has been structurally characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, emission spectroscopy, and solid-state NMR spectroscopy. It is one of the few uranium fluoride-organic framework solids in which an organic molecule is directly incorporated into the extended structure of the metal fluoride and is the first example of mixed-metal uranium oxyfluoride incorporating an organic ligand. The structure consists of neutral layers of edge- and corner-sharing uranium-centered pentagonal bipyramids and zinc-centered octahedra, which are linked through 4,4'-bpy ligands into a 3-D framework. The 1H MAS NMR spectrum is in support of the conclusion that the occluded 4,4'-bpy molecules in the structural channels are not protonated. Crystal data: monoclinic, space group P2(1)/c, a = 9.4630(5) A, b = 22.384(1) A, c = 16.7534(8) A, beta = 91.899(2) degrees , V = 3546.7(4) A(3) and Z = 4.     

Novel hydrogen-bonded three-dimensional networks encapsulating one-dimensional covalent chains: [M(4,4'-bipy)(H2O)(4)](4-abs)(2).nH2O (4,4'-bipy = 4,4'-bipyridine; 4-abs = 4-aminobenzenesulfonate) (M = Co,n = 1; M = Mn,n = 2)

Two novel compounds, [Co(4,4'-bipy)(H(2)O)(4)](4-abs)(2).H(2)O (1) and [Mn(4,4'-bipy)(H(2)O)(4)](4-abs)(2).2H(2)O (2) (4,4'-bipy = 4,4'-bipyridine; 4-abs = 4-aminobenzenesulfonate), have been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses, UV-vis and IR spectra, and TG analysis. X-ray structural analysis revealed that 1 and 2 both possess unusual hydrogen-bonded three-dimensional (3-D) networks encapsulating one-dimensional (1-D) covalently bonded infinite [M(4,4'-bipy)(H(2)O)(4)](2+) (M = Co, Mn) chains. The 4-abs anions in 1 form 1-D zigzag chains through hydrogen bonds. These chains are further extended through crystallization water molecules into 3-D hydrogen-bonded networks with 1-D channels, in which the [Co(4,4'-bipy)(H(2)O)(4)](2+) linear covalently bonded chains are located. Crystal data for 1: C(22)H(30)CoN(4)O(11)S(2), monoclinic P2(1), a = 11.380(2) A, b = 8.0274(16) A, c = 15.670(3) A, alpha = gamma = 90 degrees, beta = 92.82(3) degrees, Z = 2. Compound 2 contains interesting two-dimensional (2-D) honeycomb-like networks formed by 4-abs anions and lattice water molecules via hydrogen bonding, which are extended through other crystallization water molecules into three dimensions with 1-D hexagonal channels. The [Mn(4,4'-bipy)(H(2)O)(4)](2+) linear covalent chains exist in these channels. Crystal data for 2: C(22)H(32)MnN(4)O(12)S(2), monoclinic P2(1)/c, a = 15.0833(14) A, b = 8.2887(4) A, c = 23.2228(15) A, alpha = gamma = 90 degrees, beta = 95.186(3) degrees, Z = 4.     

Excision of uranium oxide chains and ribbons in the novel one-dimensional uranyl iodates K(2)[(UO(2))3(IO(3))(4)O(2)] and Ba[(UO(2)2(IO(3))(2)O(2)](H(2)O)

The alkali metal and alkaline-earth metal uranyl iodates K(2)[(UO(2))(3)(IO(3))(4)O(2)] and Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) have been prepared from the hydrothermal reactions of KCl or BaCl(2) with UO(3) and I(2)O(5) at 425 and 180 degrees C, respectively. While K(2)[(UO(2))(3)(IO(3))(4)O(2)] can be synthesized under both mild and supercritical conditions, the yield increases from <5% to 73% as the temperature is raised from 180 to 425 degrees C. Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O), however, has only been isolated from reactions performed in the mild temperature regime. Thermal measurements (DSC) indicate that K(2)[(UO(2))(3)(IO(3))(4)O(2)] is more stable than Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) and that both compounds decompose through thermal disproportionation at 579 and 575 degrees C, respectively. The difference in the thermal behavior of these compounds provides a basis for the divergence of their preparation temperatures. The structure of K(2)[(UO(2))(3)(IO(3))(4)O(2)] is composed of [(UO(2))(3)(IO(3))(4)O(2)](2)(-) chains built from the edge-sharing UO(7) pentagonal bipyramids and UO(6) octahedra. Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) consists of one-dimensional [(UO(2))(2)(IO(3))(2)O(2)](2)(-) ribbons formed from the edge sharing of distorted UO(7) pentagonal bipyramids. In both compounds the iodate groups occur in both bridging and monodentate binding modes and further serve to terminate the edges of the uranium oxide chains. The K(+) or Ba(2+) cations separate the chains or ribbons in these compounds forming bonds with terminal oxygen atoms from the iodate ligands. Crystallographic data: K(2)[(UO(2))(3)(IO(3))(4)O(2)], triclinic, space group P_1, a = 7.0372(5) A, b = 7.7727(5) A, c = 8.9851(6) A, alpha = 93.386(1) degrees, beta = 105.668(1) degrees, gamma = 91.339(1) degrees, Z = 1; Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O), monoclinic, space group P2(1)/c, a = 8.062(4) A, b = 6.940(3) A, c = 21.67(1), beta= 98.05(1) degrees, Z = 4.     

Single crystal structure determination of a new zirconium N-ethylpyridinium phosphonate: Zr(O(3)PCH(2)CH(2)NC(5)H(5))(F(-))(3)

We describe the structure of a new zirconium N-ethylpyridinium phosphonate, Zr(O(3)PCH(2)CH(2)NC(5)H(5))(F(-))(3), that has been determined by single-crystal X-ray analysis (monoclinic, P2(1)/c (No. 14), a = 12.3634(12) A, b = 9.3090(17) A, c = 9.8077(13) A, beta = 112.819(8) degrees, V = 1040.4(3) A(3), Z = 4). This structure is unlike any other reported zirconium phosphonate. Octahedral coordination about zirconium is completed by three oxygen atoms of three different phosphonate groups and three fluoride ligands. The structure is composed of corrugated infinite layers of these Zr octahedra that corner share their three oxygen atoms with the phosphonate tetrahedra. The appended cationic pyridinium groups lie between the inorganic sheets and are charge-balanced by the [Zr(O(3)P-)(3)F(3)](-) octahedra. This structure represents a new example of the structure-directing influence of cationic organic ligands on the zirconium phosphonate framework.     

Structure,magnetism, and electrochemistry of the multinickel polyoxoanions [Ni6As3W24O94(H2O)2]17-, [Ni3Na(H2O)2(AsW9O34)2]11-, and [Ni4Mn2P3W24O94(H2O)2]17-

The three novel, multi-nickel-substituted heteropolytungstates [Ni(6)As(3)W(24)O(94)(H(2)O)(2)](17)(-) (1), [Ni(3)Na(H(2)O)(2)(AsW(9)O(34))(2)](11)(-) (2), and [Ni(4)Mn(2)P(3)W(24)O(94)(H(2)O)(2)](17)(-) (3) have been synthesized and characterized by IR, elemental analysis, electrochemistry, and magnetic studies. Single-crystal X-ray analysis was carried out on Na(16.5)Ni(0.25)[Ni(6)As(3)W(24)O(94)(H(2)O)(2)].54H(2)O, which crystallizes in the triclinic system, space group P1, with a = 17.450(4) A, b = 17.476(4) A, c = 22.232(4) A, alpha = 85.73(3) degrees, beta = 89.74(3) degrees, gamma = 84.33(3) degrees, and Z = 2, Na(11)[Ni(3)Na(H(2)O)(2)(AsW(9)O(34))(2)].30.5H(2)O, which crystallizes in the triclinic system, space group P1, with a = 12.228(2) A, b = 16.743(3) A, c = 23.342(5) A, alpha = 78.50(3) degrees, beta = 80.69(3) degrees, gamma = 78.66(3) degrees, and Z = 2, and Na(17)[Ni(4)Mn(2)P(3)W(24)O(94)(H(2)O)(2)].50.5H(2)O, which crystallizes in the monoclinic system, space group P2(1)/c, with a = 17.540(4) A, b = 22.303(5) A, c = 35.067(7) A, beta = 95.87(3) A, and Z = 4. Polyanion 1 consists of two B-alpha-(Ni(3)AsW(9)O(40)) Keggin moieties linked via a unique AsW(6)O(16) fragment, leading to a banana-shaped structure with C(2)(v)() symmetry. The mixed-metal tungstophosphate 3 is isostructural with 1. Polyanion 2 consists of two lacunary B-alpha-[AsW(9)O(34)](9)(-) Keggin moieties linked via three nickel(II) centers and a sodium ion. Electrochemical studies show that 1-3 exhibit a unique and reproducible voltammetric pattern and that all three compounds are stable in a large pH range. An investigation of the magnetic properties of 1-3 indicates that the exchange interactions within the trimetal clusters are ferromagnetic. However, for 1 and 3 intra- and intermolecular interactions between different trinuclear clusters are also present.     

K3(U3O6)(Si2O7) and Rb3(U3O6)(Ge2O7): a pentavalent-uranium silicate and germanate

A new uranium(V) silicate, K3(U3O6)(Si2O7), and the germanate analogue, Rb3(U3O6)(Ge2O7), have been synthesized under high-temperature, high-pressure hydrothermal conditions and characterized by single-crystal X-ray diffraction. Their structures contain uranate columns formed of triple octahedral chains of the alpha-UF5 type linked by disilicate (or digermanate) units to form a 3-D framework structure. The valence state of uranium is confirmed by X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and magnetic susceptibility.