Synthesis, structure determination, and infrared spectroscopy of (NpO2)2(SO4)(H2O)4: Prevalence of cation-cation interactions and cationic nets in neptunyl sulfate compounds

The compound (NpO₂)₂(SO₄)(H₂O)₄ was synthesized by evaporation of a Np⁵⁺ sulfate solution. The crystal structure was determined using single crystal X-ray diffraction and refined to an R₁=0.0310. (NpO₂)₂(SO₄)(H₂O)₄ crystallizes in triclinic space group P-1, a=8.1102(7) Å, b=8.7506(7) Å, c=16.234(1) Å, α=90.242(2)°, β=92.855(2)°, γ=113.067(2)°, V=1058.3(2) Å³, and Z=2. The structure contains neptunyl pentagonal bipyramids that share vertices through cation-cation interactions to form a sheet or cationic net. The sheet is decorated on each side by vertex sharing with sulfate tetrahedra, and adjacent sheets are linked together through hydrogen bonding. A graphical representation of (NpO₂)₂(SO₄)(H₂O)₄ was constructed to facilitate the structural comparison to similar Np⁵⁺ compounds. The prevalence of the cationic nets in neptunyl sulfate compounds related to the overall stability of the structure is also discussed.     

Hexatungstate subunit as building block in the hydrothermal synthesis of organic-inorganic hybrid materials: synthesis, structure and optical properties of Co2(bpy)6 (W6O19)2 (bpy=4,4′-bipyridine)

A hydrothermal reaction of WO₃, CoCl₂ and 4,4′-bipyridine, yields a novel organic-inorganic hybrid compound, Co₂(bpy)₆(W₆O₁₉)₂, at 170°C. X-ray single crystal structure determination reveals a two-dimensional covalent structure belonging to monoclinic crystal system, space group C2/c, with cell parameters a=19.971(4) Å, b=11.523(2) Å, c=16.138(3) Å, β=96.49(3)°, V=3690.0 Å³ and Z=2. The hexatungstate, [W₆O₁₉]²⁻, acts as a building block in bidentate fashion to bridge the Co(II) centers in the crystal structure. The title compound is found to have an optical energy gap of 2.2 eV from UV-Vis-NIR reflectance spectra.     

Synthesis,molecular and supramolecular structure,spectroscopy and electrochemistry of a dialkoxo-bridged diuranyl(VI) compound

The synthesis, molecular and supramolecular structure, spectroscopy and electrochemistry of a dialkoxo-bridged diuranyl(VI) compound [(UO₂)₂(L)₂(dimethylformamide)₂] (1) derived from the Schiff base ligand H₂L, obtained on condensation of 3-methoxysalicylaldehyde with 2-aminoethanol, have been described. The compound has been characterized by IR, UV–Vis, NMR and mass spectra, as well as by single crystal X-ray structure determination. The title compound crystallizes in the monoclinic P2₁/n space group with the following unit cell parameters a = 10.5713(2) Å, b = 11.9895(2) Å, c = 12.9372(2) Å, β = 102.773(3)° and Z = 2. The structure of 1 reveals that it is a dialkoxo-bridged dinuclear compound of uranium(VI) containing two deprotonated ligands, [L]²⁻, two dimethylformamide (dmf) molecules and two UO₂²⁺ centers. The coordination geometry around the uranium(VI) center is distorted pentagonal bipyramidal; two uranyl oxygens occupy the axial positions, while the basal pentagonal plane is defined by a phenoxo oxygen, two bridging alkoxo oxygens, one imine nitrogen, and one dmf oxygen. Three C–H?O type hydrogen bonds involving one uranyl oxygen, two dmf hydrogens and the imine hydrogen link the dinuclear units into a two-dimensional network. The ESI-MS spectrum of 1 in dimethylsulfoxide exhibits two peaks at m/z = 464.17 and 927.26, which are assignable to [(UO₂)₂L₂H]⁺ (60%) and [(UO₂)₂LH]⁺ (100%) cations, respectively. Cyclic voltammetric measurements of 1 reveal that the uranium(VI) center is reduced quasireversibly at E_1/2 = −1112 mV with ΔE_P = 97 mV.     

New one-dimensional uranyl and neptunyl iodates: crystal structures of K3[(UO2)2(IO3)6](IO3)·H2O and K[NpO2(IO3)3]·1.5H2O

The uranyl and neptunyl(VI) iodates, K₃[(UO₂)₂(IO₃)₆](IO₃)·H₂O (1) and K[NpO₂(IO₃)₃]·1.5H₂O (2), have been prepared and crystallized under mild hydrothermal conditions. The structures of 1 and 2 both contain one-dimensional _∞¹[AnO₂(IO₃)₃]¹⁻(An=U,Np) ribbons that consist of approximately linear actinyl(VI) cations bound by iodate anions to yield AnO₇ pentagonal bipyramids. The AnO₇ units are linked by bridging iodate anions to yield chains that are in turn coupled by additional iodate anions to yield ribbons. The edges of the ribbons are terminated by monodentate iodate anions. For 1 and 2, K⁺ cations and water molecules separate the ribbons from one another. In addition, isolated iodate anions are also found between _∞¹[UO₂(IO₃)₃]¹⁻ ribbons in 1. In order to aid in the assignment of oxidation states in neptunyl containing compounds, a bond-valence sum parameter of 2.018 Å for Np(VI) bound exclusively to oxygen has been developed with b=0.37 Å. Crystallographic data (193 K, MoKα, λ=0.71073): 1, triclinic, , a=7.0609(4) Å, b=14.5686(8)  Å, c=14.7047(8)  Å, α=119.547(1)°, β=95.256(1)°, γ=93.206(1)°, Z=2, R(F)=2.49% for 353 parameters with 6414 reflections with I>2σ(I); (203 K, MoKα, λ=0.71073): 2, monoclinic, P2₁/c, a=7.796(4)  Å, b=7.151(3)  Å, c=21.79(1)  Å, β=97.399(7)°, Z=4, R(F)=6.33% for 183 parameters with 2451 reflections with I>2σ(I).     

Hydrothermal synthesis of two layered indium oxalates with 12-membered apertures

Two layered indium oxalates, In(C₂O₄)_2.5(C₃N₂H₁₂)(H₂O)₃, I, and In(C₂O₄)_1.5(H₂O)₃, II, have been hydrothermally synthesized. In I, the linkage between indium and oxalate units gives rise to a sheet with a rectangular 12-membered aperture (six indium atoms and six oxalate units). Indium atom of II has an unusual pentagonal bipyramidal coordination arrangement. The connectivity between indium and oxalate units forms a neutral puckered layer with 12- (along a-axis) and eight-membered (along b-axis) apertures. Crystal data for these two indium oxalates are as follows: I, triclinic, space group: P-1 (No. 2), a=8.725(3) Å, b=9.170(3) Å, c=9.901(3) Å, α=98.101(4)°, β=97.068(4)°, γ=102.403(4)°, V=756.3(4) Å³, Z=2, M=463.0(5), ρ_calc=2.042 g/cm³, R₁=0.0377, wR₂=0.0834. II, monoclinic, space group: P2₁/c (No. 14), a=10.203(5) Å, b=6.638(1) Å, c=11.152(7) Å, β=95.649(4)°, V=751.7(4)ų, Z=4, M=300.9(0), ρ_calc=2.659 g/cm³, R₁=0.0229, wR₂=0.0488. TG analyses indicate the water molecules of I can be removed at 150°C. The dehydrated product retains structural integrity.     

New alkali-metal-molybdenum(VI)-selenium(IV) oxides: syntheses, structures, and characterization of A2SeMoO6 (A=Na, K, or Rb)

Three new quaternary selenites, A₂SeMoO₆ (A=Na⁺, K⁺, or Rb⁺), were synthesized through the solid-state reaction of A₂MoO₄ with SeO₂ at 400°C. Although the reported materials are ‘stoichiometrically equivalent’, the compounds exhibit strikingly different crystal structures. Whereas Na₂SeMoO₆ has a three-dimensional crystal structure, K₂SeMoO₆ and Rb₂SeMoO₆ are molecular and uni-dimensional, respectively. However, all of the new materials have structures containing Mo⁶⁺ octahedra linked to Se⁴⁺ trigonal pyramids. Although the Mo⁶⁺ and Se⁴⁺ cations are in local asymmetric environments in all three materials, only Na₂SeMoO₆ is non-centrosymmetric. Single crystal X-ray data: Na₂SeMoO₆, cubic, space group, P2₁3 (no. 198), a=8.375(5) Å, Z=4, R(F)=0.0143; K₂SeMoO₆, monoclinic, space group, P2₁/c (no. 14), a=6.118(8) Å, b=15.395(2) Å, c=7.580(9) Å, β=112.39(4)°, Z=4, R(F)=0.0281; Rb₂SeMoO₆, orthorhombic, space group, Pnma (no. 62), a=7.805(9) Å, b=6.188(7) Å, c=14.405(4) Å, Z=4, R(F)=0.0443.     

Molecular hexagonal perovskite: a new type of organic-inorganic hybrid conductor

An organic charge-transfer (CT) salt (BEDT-TTF)₃(MnCl₃)₂(C₂H₅OH)₂ has been synthesized by a standard electrochemical method. The crystal data are monoclinic, C2/c (#15), a=38.863(4)Å, b=6.716(1) Å, c=23.608(3) Å, β=115.007(3)°, V=5584(1) Å³, and Z=4. The structure consists of one-dimensional (1D) infinite {[MnCl₃]⁻}_∞ magnetic chains and two-dimensional (2D) organic conduction pathways. The former consists of face-sharing octahedra of manganese chloride complex ions, and dominates the magnetic properties of this compound. Such a feature of the crystal structure closely relates to transition metal hexagonal perovskite compounds, all of which are known for frustrated triangular lattices comprised of weakly interacting 1D magnetic chains. The new compound exhibits a high conductivity down to 4 K.     

Four new hydroxymonophosphates with closely related intersecting tunnels structures: The series AM(PO3(OH))2 with A=Rb, Cs; M=Fe, Al, Ga, In

The family of hydroxymonophosphates of generic formula AM^III(PO₃(OH))₂ has been revisited using hydrothermal techniques. Four new phases have been synthesized: CsIn(PO₃(OH))₂, RbFe(PO₃(OH))₂, RbGa(PO₃(OH))₂ and RbAl(PO₃(OH))₂. Single crystal diffraction studies show that they exhibit two different structural types from previously observed other phases with A=H₃O, NH₄, Rb and M=Al, V, Fe. The “Cs-In” and “Rb-Fe” phosphates crystallize in the triclinic space group , with the cell parameters a=7.4146(3) Å, b=9.0915(3) Å, c=9.7849(3) Å, α=65.525(3)°, β=70.201(3)°, γ=69.556(3)° and V=547.77(4) Å³ (Z=3) for CsIn(PO₃(OH))₂ and a=7.2025(4) Å, b=8.8329(8) Å, c=9.4540(8) Å, α=65.149(8)°, β=70.045(6)°, γ=69.591(6)° and V=497.44(8) Å³ (Z=3) for α-RbFe(PO₃(OH))₂. The “Rb-Al” and “Rb-Ga” phosphates crystallize in the Rc space group, with a=8.0581(18) Å and c=51.081(12) Å (V=2872.5(11) Å³ and Z=18) for RbAl(PO₃(OH))₂ and a=8.1188(15) Å and c=51.943(4) Å (V=2965(8) Å and Z=18) for RbGa(PO₃(OH))₂. These two structural types are closely related. Both are built up from M^IIIO6 octahedra sharing their apices with PO₃(OH) tetrahedra to form [M₃(PO₃OH)₆] units, but the latter exhibits a different configuration of their tetrahedra. The three-dimensional host-lattices result from the connection of the [M₃(PO₃OH)₆] units and they present numerous intersecting tunnels containing the monovalent cations.     

Pb(UO2)(V2O7), a novel lead uranyl divanadate

A new lead uranyl divanadate, PbUO₂(V₂O₇), has been synthesized by high temperature solid-state reaction and its crystal structure was solved by direct methods using single-crystal X-ray diffraction data. It crystallizes in the monoclinic system with space group P2₁/n and following cell parameters: a=6.9212(9) Å, b=9.6523(13) Å, c=11.7881(16) Å, β=91.74(1)°, V=787.01(2) Å³, Z=4, ρ_mes=5.82(3), ρ_cal=5.83(1) g/cm³. A full-matrix least-squares refinement on the basis of F² yielded R₁=0.029 and wR₂=0.064 for 2136 independent reflections with I>2σ(I) collected with a Bruker AXS diffractometer (MoKα radiation). The crystal structure of PbUO₂(V₂O₇) consists of a tri-dimensional framework resulting from the association of V₂O₇ divanadate units formed by two VO₄ tetrahedra sharing corner and UO₇ uranyl pentagonal bipyramids and creating one-dimensional elliptic channels occupied by the Pb²⁺ ions. In PbUO₂(V₂O₇), infinite ribbons of four pentagons wide are formed which can be deduced from the sheets with Uranophane type anion-topology that occurs, for example, in the uranyl divanadate (UO₂)₂(V₂O₇), by replacement of half-U atoms of the edge-shared UO₇ pentagonal bipyramids by Pb atoms. Infrared spectroscopy was investigated at room temperature in the frequency range 400-4000 cm⁻¹, showing some characteristic bands of uranyl ion and of VO₄ tetrahedra.     

Synthesis and structural investigation of the compounds containing HF2 anions: Ca(HF2)2, Ba4F4(HF2)(PF6)3 and Pb2F2(HF2)(PF6)

Three new compounds Ca(HF₂)₂, Ba₄F₄(HF₂)(PF₆)₃ and Pb₂F₂(HF₂)(PF₆) were obtained in the system metal(II) fluoride and anhydrous HF (aHF) acidified with excessive PF₅. The obtained polymeric solids are slightly soluble in aHF and they crystallize out of their aHF solutions. Ca(HF₂)₂ was prepared by simply dissolving CaF₂ in a neutral aHF. It represents the second known compound with homoleptic HF environment of the central atom besides Ba(H₃F₄)₂. The compounds Ba₄F₄(HF₂)(PF₆)₃ and Pb₂F₂(HF₂)(PF₆) represent two additional examples of the formation of a polymeric zigzag ladder or ribbon composed of metal cation and fluoride anion (MF⁺)_n besides PbF(AsF₆), the first isolated compound with such zigzag ladder. The obtained new compounds were characterized by X-ray single crystal diffraction method and partly by Raman spectroscopy. Ba₄F₄(HF₂)(PF₆)₃ crystallizes in a triclinic space group P1¯ with a=4.5870(2) Å, b=8.8327(3) Å, c=11.2489(3) Å, α=67.758(9)°, β=84.722(12), γ=78.283(12)°, V=413.00(3) Å³ at 200 K, Z=1 and R=0.0588. Pb₂F₂(HF₂)(PF₆) at 200 K: space group P1¯, a=4.5722(19) Å, b=4.763(2) Å, c=8.818(4) Å, α=86.967(10)°, β=76.774(10)°, γ=83.230(12)°, V=185.55(14) ų, Z=1 and R=0.0937. Pb₂F₂(HF₂)(PF₆) at 293 K: space group P1¯, a=4.586(2) Å, b=4.781(3) Å, c=8.831(5) Å, α=87.106(13)°, β=76.830(13)°, γ=83.531(11)°, V=187.27(18) Å³, Z=1 and R=0.072. Ca(HF₂)₂ crystallizes in an orthorhombic Fddd space group with a=5.5709(6) Å, b=10.1111(9) Å, c=10.5945(10) Å, V=596.77(10) Å³ at 200 K, Z=8 and R=0.028.     

Synthesis and crystal structure of a new open-framework iron phosphate (NH4)4Fe3(OH)2F2[H3(PO4)4]: Novel linear trimer of corner-sharing Fe(III) octahedra

A new iron phosphate (NH₄)₄Fe₃(OH)₂F₂[H₃(PO₄)₄] has been synthesized hydrothermally at HF concentrations from 0.5 to 1.2 mL. Single-crystal X-ray diffraction analysis reveals its three-dimensional open-framework structure (monoclinic, space group P2₁/n (No. 14), a=6.2614(13) Å, b=9.844(2) Å, c=14.271(3) Å, β=92.11(1)°, V=879.0(3) Å³). This structure is built from isolated linear trimers of corner-sharing Fe(III) octahedra, which are linked by (PO₄) groups to form ten-membered-ring channels along [1 0 0]. This isolated, linear trimer of corner-sharing Fe(III) octahedra, [(FeO₄)₃(OH)₂F₂], is new and adds to the diverse linkages of Fe polyhedra as secondary building units in iron phosphates. The trivalent iron at octahedral sites for the title compound has been confirmed by synchrotron Fe K-edge XANES spectra and magnetic measurements. Magnetic measurements also show that this compound exhibit a strong antiferromagnetic exchange below T_N=17 K, consistent with superexchange interactions expected for the linear trimer of ferric octahedra with the Fe-F-Fe angle of 132.5°.     

Two new octahedral/pyramidal frameworks containing both cation channels and lone-pair channels: syntheses and structures of Ba2MnMn2(SeO3)6 and PbFe2(SeO3)4

The hydrothermal syntheses, single crystal structures, and some properties of Ba₂Mn^IIMn₂^III(SeO₃)₆ and PbFe₂(SeO₃)₄ are reported. These related phases contain three-dimensional frameworks of vertex (FeO₆) and vertex/edge linked (MnO₆) octahedra and SeO₃ pyramids. In each case, the MO₆/SeO₃ framework encloses two types of 8 ring channels, one of which encapsulates the extra-framework cations and one of which provides space for the Se^IV lone pairs. Crystal data: Ba₂Mn₃(SeO₃)₆, M_r=1201.22, monoclinic, P2₁/c (No. 14), a=5.4717 (3) Å, b=9.0636 (4) Å, c=17.6586 (9) Å, β=94.519 (1)°, V=873.03 (8) Å³, Z=2, R(F)=0.031, wR(F²)=0.070; PbFe₂(SeO₃)₄, M_r=826.73, triclinic, (No. 2), a=5.2318 (5) Å, b=6.7925 (6) Å, c=7.6445 (7) Å, α=94.300 (2)°, β=90.613 (2)°, γ=95.224 (2)°, V=269.73 (4) Å³, Z=1, R(F)=0.051, wR(F²)=0.131.     

Synthesis and crystal structure of new uranyl tungstates M2(UO2)(W2O8) (M=Na, K), M2(UO2)2(WO5)O (M=K, Rb), and Na10(UO2)8(W5O20)O8

The solid-state reactions of UO₃ and WO₃ with M₂CO₃ (M=Na, K, Rb) at 650°C for 5 days result, accordingly the starting stoichiometry, in the formation of M₂(UO₂)(W₂O₈) (M=Na (1), K (2)), M₂(UO₂)₂(WO₅)O (M=K (3), Rb (4)), and Na₁₀(UO₂)₈(W₅O₂₀)O₈ (5). The crystal structures of compounds 2, 3, 4, and 5 have been determined by single-crystal X-ray diffraction using Mo(Kα) radiation and a charge-coupled device detector. The crystal structures were solved by direct methods and Fourier difference techniques, and refined by a least-squares method on the basis of F² for all unique reflections. For (1), unit-cell parameters were determined from powder X-ray diffraction data. Crystallographic data: 1, monoclinic, a=12.736(4) Å, b=7.531(3) Å, c=8.493(3) Å, β=93.96(2)°, ρ_cal=6.62(2) g/cm³, ρ_mes=6.64(1) g/cm³, Z=4; 2, orthorhombic, space group Pmcn, a=7.5884(16) Å, b=8.6157(18) Å, c=13.946(3) Å, ρ_cal=6.15(2) g/cm³, ρ_mes=6.22(1) g/cm³, Z=8, R1=0.029 for 80 parameters with 1069 independent reflections; 3, monoclinic, space group P2₁/n, a=8.083(4) Å, b=28.724(5) Å, c=9.012(4) Å, β=102.14(1)°, ρ_cal=5.83(2) g/cm³, ρ_mes=5.90(2) g/cm³, Z=8, R1=0.037 for 171 parameters with 1471 reflections; 4, monoclinic, space group P2₁/n, a=8.234(1) Å, b=28.740(3) Å, c=9.378(1) Å, β=104.59(1)°, ρ_cal=6.13(2) g/cm³,  g/cm³, Z=8, R1=0.037 for 171 parameters with 1452 reflections; 5, monoclinic, space group C2/c, a=24.359(5) Å, b=23.506(5) Å, c=6.8068(14) Å, β=94.85(3)°, ρ_cal=6.42(2) g/cm³,  g/cm³, Z=8, R1=0.036 for 306 parameters with 5190 independent reflections. The crystal structure of 2 contains linear one-dimensional chains formed from edge-sharing UO₇ pentagonal bipyramids connected by two octahedra wide (W₂O₈) ribbons formed from two edge-sharing WO₆ octahedra connected together by corners. This arrangement leads to [UW₂O₁₀]²⁻ corrugated layers parallel to (001). Owing to the unit-cell parameters, compound 1 probably contains similar sheets parallel to (100). Compounds 3 and 4 are isostructural and the structure consists of bi-dimensional networks built from the edge- and corner-sharing UO₇ pentagonal bipyramids. This arrangement creates square sites occupied by W atoms, a fifth oxygen atom completes the coordination of W atoms to form WO₅ distorted square pyramids. The interspaces between the resulting [U₂WO₁₀]²⁻ layers parallel to plane are occupied by K or Rb atoms. The crystal structure of compound 5 is particularly original. It is based upon layers formed from UO₇ pentagonal bipyramids and two edge-shared octahedra units, W₂O₁₀, by the sharing of edges and corners. Two successive layers stacked along the [100] direction are pillared by WO₄ tetrahedra resulting in sheets of double layers. The sheets are separated by Na⁺ ions. The other Na⁺ ions occupy the rectangular tunnels created within the sheets. In fact complex anions W₅O₂₀¹⁰⁻ are built by the sharing of the four corners of a WO₄ tetrahedron with two W₂O₁₀ dimmers, so, the formula of compound 5 can be written Na₁₀(UO₂)₈(W₅O₂₀)O₈.     

Synthesis, crystal structure and magnetic characterization of Na2Cu5(Si2O7)2: An inorganic ferrimagnetic chain

The hydrothermal synthesis, crystal structure and magnetic properties of the new copper silicate Na₂Cu₅(Si₂O₇)₂, are reported. The crystal structure was determined through synchrotron powder diffraction data. The unit cell was indexed to a triclinic cell, space group P-1 (n° 2) with unit cell parameters a=5.71075(2) Å, b=7.68266(3) Å, c=7.96742(3) Å, α=64.2972(2)°, β=88.4860(2)° and γ=70.5958(2)° with Z=1. A structural model was obtained through a combination of a direct-space Monte-Carlo approach and Rietveld refinement. The crystal structure contains parallel chains consisting of zig-zag copper dimers and trimers. All silicon atoms are present as part of a [Si₂O₇]⁶⁻ anion that connects the chains; therefore the compound belongs to the sorosilicate mineral family. The magnetic susceptibility was measured and shows a behavior typical of one-dimensional ferrimagnetism, in agreement with the observed structure.     

Hydrothermal syntheses and structures of the uranyl tellurates AgUO2(HTeO5) and Pb2UO2(TeO6)

Two uranyl tellurates, AgUO₂(HTeO₅) (1) and Pb₂UO₂(TeO₆) (2), were synthesized under hydrothermal conditions and were structurally, chemically, and spectroscopically characterized. 1 crystallizes in space group Pbca, a=7.085(2) Å, b=11.986(3) Å, c=13.913(4) Å, V=1181.5(5) Å³, Z=8; 2 is in P2(1)/c, a=5.742(1) Å, b=7.789(2) Å, c=7.928(2) Å, V=90.703(2) Å³, and Z=2. These are the first structures reported for uranyl compounds containing tellurate. The U⁶⁺ cations are present as (UO₂)²⁺ uranyl ions that are coordinated by O atoms to give pentagonal and square bipyramids in compounds 1 and 2, respectively. The structural unit in 1 is a sheet consisting of chains of edge-sharing uranyl pentagonal bipyramids that are one bipyramid wide, linked through the dimers of TeO₆ octahedra. In 2, uranyl square bipyramids share each of their equatorial vertices with different TeO₆ octahedra, giving a sheet with the autunite-type topology. Sheets in 1 and 2 are connected through the low-valence cations that are located in the interlayer region. The structures of 1 and 2 are compared to those of uranyl compounds containing octahedrally coordinated cations.     

Synthesis and structure of [C6H14N2][(UO2)4(HPO4)2(PO4)2(H2O)]·H2O: An expanded open-framework amine-bearing uranyl phosphate

A new open-framework compound, [C₆H₁₄N₂][(UO₂)₄(HPO₄)₂(PO₄)₂(H₂O)]·H₂O, (DUP-1) has been synthesized under mild hydrothermal conditions. The resulting structure consists of diprotonated DABCOH₂²⁺ (C₆H₁₄N₂²⁺) cations and occluded water molecules occupying the channels of a complex uranyl phosphate three-dimensional framework. The anionic lattice contains uranophane-like sheets connected by hydrated pentagonal bipyramidal UO₇ units. [C₆H₁₄N₂][(UO₂)₄(HPO₄)₂(PO₄)₂(H₂O)]·H₂O possesses five crystallographically unique U centers. U(VI) is present here in both six- and seven-coordinate environments. The DABCOH₂²⁺ cations are held within the channels by hydrogen bonds to both two uranyl oxygen atoms and a μ₂-O atom. Crystallographic data (193 K, Mo Kα, λ=0.71073 Å): DUP-1, monoclinic, P2₁/n, a=7.017(1) Å, b=21.966(4) Å, c=17.619(3) Å, β=90.198(3)°, Z=4, R(F)=4.76% for 382 parameters with 6615 reflections with I>2σ(I).     

Crystal structures and photocatalysis of the triclinic polymorphs of BiNbO4 and BiTaO4

The high-temperature polymorphs of two photocatalytic materials, BiNbO₄ and BiTaO₄ were synthesized by the ceramic method. The crystal structures of these materials were determined by single-crystal X-ray diffraction. BiNbO₄ and BiTaO₄ crystallize into the triclinic system P1¯ (No. 2), with a=5.5376(4) Å, b=7.6184(3) Å, c=7.9324(36) Å, α=102.565(3)°, β=90.143(2)°, γ=92.788 (4)°, V=326.21 (5) Å³, Z=4 and a=5.931 (1) Å, b=7.672 (2) Å, c=7.786 (2) Å, α=102.94 (3)°, β=90.04 (3)° γ=93.53 (3)°, V=344.59 (1) Å³ and Z=4, respectively. The structures along the c-axis, consist of layers of [Bi₂O₂] units separated by puckered sheets of (Nb/Ta)O₆ octahedra. Photocatalytic studies on the degradation of dyes indicate selectivity of BiNbO₄ towards aromatics containing quinonic and azo functional groups.     

Syntheses and crystal structures of binuclear ruthenium complexes bearing 1,8′-bis(diphenylphosphinomethyl)naphthalene

Treatment of [RuCl₂(η⁶-C₆H₆)]_x with bidentate phosphine ligand BDNA [1,8-bis(diphenylphosphinomethyl)naphthalene] in methanol at room temperature gave η⁶-benzene-ruthenium complexes Ru₂Cl₄(η⁶-C₆H₆)₂(μ-BDNA) (1). Complex 1 further reacted with AgBF₄ to form complex [Ru₂Cl₂(μ-Cl)(η⁶-C₆H₆)₂(μ-BDNA)](BF₄) (2). [RuCl₂(η⁶-C₆H₆)]_x reacted with BDNA in refluxing methanol and then the reaction solution was treated with AgBF₄ to generate complex [Ru₂Cl₂(η⁶-C₆H₆)₂(μ-BDNA)₂](BF₄)₂ (3). Their compositions and structures had been determined by elemental analyses, NMR spectra and single crystal X-ray diffractions. X-ray diffraction showed that complex 1 belonged to monoclinic crystal system, P2₁/c space group with Z = 4, a = 12.810 Å, b = 21.507 Å, c = 18.471 Å, β = 107.95°; complex 2 belonged monoclinic crystal system, P2₁/n space group with Z = 4, a = 14.498 Å, b = 15.644 Å, c = 20.788 Å, β = 103.404°, and complex 3 belonged to monoclinic crystal system, P2₁/n space group with Z = 2, a = 13.732 Å, b = 14.351 Å, c = 19.733 Å, β = 94.82°.     

Synthesis and crystal structure of CuZrTiO5—A new crystal structure type

A new compound, CuZrTiO₅, was synthesized as strongly pleochroic green crystals from the oxides between 995 and 1010 °C, 1 atm. Its crystal structure was determined by single crystal XRD, resulting in R (F²>2σ(F²))=0.032 and wR (all data)=0.079). CuZrTiO₅ is orthorhombic, space group P2₁2₁2₁, a=3.5871(3) Å, b=6.6968(4) Å, c=14.6679(9) Å, V=352.35(4) Å³, Z=4. The structure is topologically similar to In₂TiO₅ but differs in space group and cation coordination. CuZrTiO₅ has relatively regular TiO₆ polyhedra, but coordination is 7+1 for Zr, and 4+2 for Cu due to the Jahn-Teller effect. Ordering of the long Cu-O bonds causes reduction in symmetry relative to In₂TiO₅. Layers of Cu alternate with Ti+Zr on (001), giving rise to a distinct cleavage. Bond valence sums on Ti and Zr are far from ideal, which appears due to the limited ability of this structural topology to avoid close next-nearest neighbour distances.     

Hydrothermal synthesis, crystal structure, thermal behavior and spectroscopic and magnetic properties of two new organically templated fluoro-vanadyl-hydrogenarsenates: (R)0.5[(VO)(HAsO4)F] (R: Ethylenediammonium and piperazinium)

Two new fluoro-vanadyl-hydrogenarsenate compounds templated by ethylenediamine and piperazine with formula, (C₂N₂H₁₀)_0.5[(VO)(HAsO₄)F] (1) and (C₄N₂H₁₂)_0.5[(VO)(HAsO₄)F] (2), respectively, have been synthesized by using mild hydrothermal conditions under autogenous pressure. The crystal structures have been solved from single-crystal X-ray diffraction data. The phases crystallize in the P2₁/c monoclinic space group with the unit-cell parameters a=7.8634(4) Å, b=7.7658(4) Å, c=10.4195(6) Å, β=101.524(5)° for compound (1) and a=6.301(1) Å, b=10.244(1) Å, c=10.248(1) Å and β=95.225(1)° for compound (2). These phases exhibit a layered inorganic framework. In both cases, the structure is built from secondary building units (SBU) which are formed by [V₂O₈F₂] edge-shared dimeric vanadyl octahedra, connected by the vertices to two hydrogenarsenate tetrahedra. The repetition of this SBU unit originates sheets along the [1 0 0] direction. The ethylenediammonium and piperazinium cations are located inside the interlayer space. The limit of thermal stability for compounds (1) and (2) is, approximately, 250 and 230 °C, respectively. Near this temperature, both phases loose their organic cations and the fluoride anions. The diffuse reflectance spectra confirm the presence of vanadyl ions, in which the vanadium(IV) cations have a d¹ electronic configuration in a slightly distorted octahedral environment. ESR spectra of both phases are isotropic with mean g-values of 1.93 and 1.96 for ethylendiamine and piperazine phases, respectively. Magnetic measurements for (1) and (2) indicate the existence of antiferromagnetic exchange couplings.