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 electrical characterization of two new potassium uranyl molybdates K2(UO2)2(MoO4)O2 and K8(UO2)8(MoO5)3O6

Two new potassium uranyl molybdates K₂(UO₂)₂(MoO₄)O₂ and K₈(UO₂)₈(MoO₅)₃O₆ have been obtained by solid state chemistry . The crystal structures were determined by single crystal X-ray diffraction data, collected with MoKα radiation and a charge coupled device (CCD) detector. Their structures were solved using direct methods and Fourier difference techniques and refined by a least square method on the basis of F² for all unique reflections, with R₁=0.046 for 136 parameters and 1412 reflections with I?2σ(I) for K₂(UO₂)₂(MoO₄)O₂ and R₁=0.055 for 257 parameters and 2585 reflections with I?2σ(I) for K₈(UO₂)₈(MoO₅)₃O₆. The first compound crystallizes in the monoclinic symmetry, space group P2₁/c with a=8.250(1) Å, b=15.337(2) Å, c=8.351(1) Å, β=104.75(1)°, ρ_mes=5.22(2) g/cm³, ρ_cal=5.27(2) g/cm³ and Z=4. The second material adopts a tetragonal unit cell with a=b=23.488(3) Å, c=6.7857(11) Å, ρ_mes=5.44(3) g/cm³, ρ_cal=5.49(2) g/cm³, Z=4 and space group P4/n.In both structures, the uranium atoms adopt a UO₇ pentagonal bipyramid environment, molybdenum atoms are in a MoO₄ tetrahedral environment for K₂(UO₂)₂(MoO₄)O₂ and MoO₅ square pyramid coordination in K₈(UO₂)₈(MoO₅)₃O₆. These compounds are characterized by layered structures. The association of uranyl ions (UO₇) and molybdate oxoanions MoO₄ or MoO₅, give infinite layers [(UO₂)₂(MoO₄)O₂]²⁻ and [(UO₂)₈(MoO₅)₃O₆]⁸⁻ in K₂(UO₂)₂(MoO₄)O₂ and K₈(UO₂)₈(MoO₅)₃O₆, respectively. Conductivity properties of alkali metal within the interlayer spaces have been measured and show an Arrhenius type evolution.     

New open-framework in the uranyl vanadates A3(UO2)7(VO4)5O (A=Li, Ag) with intergrowth structure between A(UO2)4(VO4)3 and A2(UO2)3(VO4)2O

New uranyl vanadates A₃(UO₂)₇(VO₄)₅O (M=Li (1), Na (2), Ag (3)) have been synthesized by solid-state reaction and their structures determined from single-crystal X-ray diffraction data for 1 and 3. The tetragonal structure results of an alternation of two types of sheets denoted S for _∞²[UO₂(VO₄)₂]⁴⁻ and D for _∞²[(UO₂)₂(VO₄)₃]⁵⁻ built from UO₆ square bipyramids and connected through VO₄ tetrahedra to _∞¹[U(3)O₅-U(4)O₅]⁸⁻ infinite chains of edge-shared U(3)O₇ and U(4)O₇ pentagonal bipyramids alternatively parallel to a- and b-axis to construct a three-dimensional uranyl vanadate arrangement. It is noticeable that similar _∞[UO₅]⁴⁻ chains are connected only by S-type sheets in A₂(UO₂)₃(VO₄)₂O and by D-type sheets in A(UO₂)₄(VO₄)₃, thus A₃(UO₂)₇(VO₄)₅O appears as an intergrowth structure between the two previously reported series. The mobility of the monovalent ion in the mutually perpendicular channels created in the three-dimensional arrangement is correlated to the occupation rate of the sites and by the geometry of the different sites occupied by either Na, Ag or Li. Crystallographic data: 293 K, Bruker X8-APEX2 X-ray diffractometer equipped with a 4 K CCD detector, MoKα, λ=0.71073 Å, tetragonal symmetry, space group P4¯m2, Z=1, full-matrix least-squares refinement on the basis of F²; 1,a=7.2794(9) Å, c=14.514(4) Å, R1=0.021 and wR2=0.048 for 62 parameters with 782 independent reflections with I?2σ(I); 3, a=7.2373(3) Å, c=14.7973(15) Å, R1=0.041 and wR2=0.085 for 60 parameters with 1066 independent reflections with I?2σ(I).     

A novel open-framework with non-crossing channels in the uranyl vanadates A(UO2)4(VO4)3 (A=Li, Na)

A new sodium uranyl vanadate Na(UO₂)₄(VO₄)₃ has been synthesized by solid-state reaction and its structure determined from single-crystal X-ray diffraction data. It crystallizes in the tetragonal symmetry with space group I4₁/amd and following cell parameters: a=7.2267(4) Å and c=34.079(4) Å, V=1779.8(2) Å³, Z=4 with ρ_mes=5.36(3) g/cm³ and ρ_cal=5.40(2) g/cm³. A full-matrix least-squares refinement on the basis of F² yielded R₁=0.028 and wR₂=0.056 for 52 parameters with 474 independent reflections with I?2σ(I) collected on a BRUKER AXS diffractometer with MoKα radiation and a CCD detector. The crystal structure is characterized by _∞²[(UO₂)₂(VO₄)] sheets parallel to (001) formed by corner-shared UO₆ distorted octahedra and V(2)O₄ tetrahedra, connected by V(1)O₄ tetrahedra to _∞¹[UO₅]⁴⁻ chains of edge-shared UO₇ pentagonal bipyramids alternately parallel to the a- and b-axis. The resulting three-dimensional framework creates mono-dimensional channels running down the a- and b-axis formed by face-shared oxygen octahedra half occupied by Na. The powder of Li analog compound Li(UO₂)₄(VO₄)₃ has been synthesized by solid-state reaction. The two compounds exhibit high mobility of the alkaline ions within the two-dimensional network of non-intersecting channels.     

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 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).     

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 and characterization of layered vanadium phosphite: [HN(C2H4)3N][(VO)2(HPO3)2(OH)(H2O)]·H2O

A novel compound, [HN(C₂H₄)₃N][(VO)₂(HPO₃)₂(OH)(H₂O)]·H₂O, was hydrothermally synthesized and characterized by single crystal X-ray diffraction. This compound crystallizes in the monoclinic system with the space group C2/c and cell parameters a=11.0753(3) Å, b=17.8265(6) Å, c=16.5229(5) Å, and β=92.362(2)°. The structure of the compound consists of vanadium phosphite layers which are built up from the infinite one-dimensional chains of [(VO)(H₂O)(HPO₃)₂]²⁻ of octahedral VO₅(H₂O) and pseudo pyramidal [HPO₃], and bridging binuclear fragments of [VO(OH)]₂. Thermogravimetric analysis and magnetic susceptibility data for this compound are given.     

Syntheses and single-crystal structures of CsTh(MoO4)2Cl and Na4Th(WO4)4

Colorless crystals of CsTh(MoO₄)₂Cl and Na₄Th(WO₄)₄ have been synthesized at 993 K by the solid-state reactions of ThO₂, MoO₃, CsCl, and ThCl₄ with Na₂WO₄. Both compounds have been characterized by the single-crystal X-ray diffraction. The structure of CsTh(MoO₄)₂Cl is orthorhombic, consisting of two adjacent [Th(MoO₄)₂] layers separated by an ionic CsCl sublattice. It can be considered as an insertion compound of Th(MoO₄)₂ and reformulated as Th(MoO₄)₂·CsCl. The Th atom coordinates to seven monodentate MoO₄ tetrahedra and one Cl atom in a highly distorted square antiprism. Na₄Th(WO₄)₄ adopts a scheelite superlattice structure. The three-dimensional framework of Na₄Th(WO₄)₄ is constructed from corner-sharing ThO₈ square antiprisms and WO₄ tetrahedra. The space within the channels is filled by six-coordinate Na ions. Crystal data: CsTh(MoO₄)₂Cl, monoclinic, P2₁/c, Z=4, a=10.170(1) Å, b=10.030(1) Å, c=9.649(1) Å, β=95.671(2)°, V=979.5(2) Å³, R(F)=2.65% for I>2σ(I); Na₄Th(WO₄)₄, tetragonal, I4₁/a, Z=4, a=11.437(1) Å, c=11.833(2) Å, V=1547.7(4) Å³, R(F)=3.02% for I>2σ(I).     

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.     

Syntheses, crystal structures and optical spectroscopy of Ln2(SO4)3·8H2O (Ln=Ho, Tm) and Pr2(SO4)3·4H2O

The lanthanide sulphate octahydrates Ln₂(SO₄)₃·8H₂O (Ln=Ho, Tm) and the respective tetrahydrate Pr₂(SO₄)₃·4H₂O were obtained by evaporation of aqueous reaction mixtures of trivalent rare earth oxides and sulphuric acid at 300 K. Ln₂(SO₄)₃·8H₂O (Ln=Ho, Tm) crystallise in space group C2/c (Z=4, a_Ho=13.4421(4) Å, b_Ho=6.6745(2) Å, c_Ho=18.1642(5) Å, β_Ho=102.006(1) Å³ and a_Tm=13.4118(14) Å, b_Tm=6.6402(6) Å, c_Tm=18.1040(16) Å, β_Tm=101.980(8) Å³), Pr₂(SO₄)₃·4H₂O adopts space group P2₁/n (a=13.051(3) Å, b=7.2047(14) Å, c=13.316(3) Å, β=92.55(3) Å³). The vibrational and optical spectra of Ho₂(SO₄)₃·8H₂O and Pr₂(SO₄)₃·4H₂O are also reported.     

Crystal structures of lazulite-type oxidephosphates TiTi3O3(PO4)3 and M4Ti27O24(PO4)24 (M=Ti, Cr, Fe)

Single crystals of the oxidephosphates Ti^IIITi^IV₃O₃(PO₄)₃ (black), Cr^III₄Ti^IV₂₇O₂₄(PO₄)₂₄ (red-brown, transparent), and Fe^III₄Ti^IV₂₇O₂₄(PO₄)₂₄ (brown) with edge-lengths up to 0.3 mm were grown by chemical vapour transport. The crystal structures of these orthorhombic members (space group F2dd ) of the lazulite/lipscombite structure family were refined from single-crystal data [Ti^IIITi^IV₃O₃(PO₄)₃: Z=24, a=7.3261(9) Å, b=22.166(5) Å, c=39.239(8) Å, R₁=0.029, wR₂=0.084, 6055 independent reflections, 301 variables; Cr^III₄Ti^IV₂₇O₂₄(PO₄)₂₄: Z=1, a=7.419(3) Å, b=21.640(5) Å, c=13.057(4) Å, R₁=0.037, wR₂=0.097, 1524 independent reflections, 111 variables; Fe^III₄Ti^IV₂₇O₂₄(PO₄)₂₄: Z=1, a=7.4001(9) Å, b=21.7503(2) Å, c=12.775(3) Å, R₁=0.049, wR₂=0.140, 1240 independent reflections, 112 variables). For Ti^IIITi^IVO₃(PO₄)₃ a well-ordered structure built from dimers [Ti^III,IV₂O₉] and [Ti^IV,IV₂O₉] and phosphate tetrahedra is found. The metal sites in the crystal structures of Cr₄Ti₂₇O₂₄(PO₄)₂₄ and Fe₄Ti₂₇O₂₄(PO₄)₂₄, consisting of dimers [M^IIITi^IVO₉] and [Ti^IV,IV₂O₉], monomeric [Ti^IVO₆] octahedra, and phosphate tetrahedra, are heavily disordered. Site disorder, leading to partial occupancy of all octahedral voids of the parent lipscombite/lazulite structure, as well as splitting of the metal positions is observed. According to Guinier photographs Ti^III₄Ti^IV₂₇O₂₄(PO₄)₂₄ (a=7.418(2) Å, b=21.933(6) Å, c=12.948(7) Å) is isotypic to the oxidephosphates M^III₄Ti^IV₂₇O₂₄(PO₄)₂₄ (M^III: Cr, Fe). The UV/vis spectrum of Cr₄Ti₂₇O₂₄(PO₄)₂₄ reveals a rather small ligand-field splitting Δ_o=14,370 cm⁻¹ and a very low nephelauxetic ratio β=0.72 for the chromophores [Cr^IIIO₆] within the dimers [Cr^IIITi^IVO₉].     

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, crystal structure, infrared and Raman spectra of Sr4Cu3(AsO4)2(AsO3OH)4·3H2O and Ba2Cu4(AsO4)2(AsO3OH)3

The two new compounds, Sr₄Cu₃(AsO₄)₂(AsO₃OH)₄·3H₂O (1) and Ba₂Cu₄(AsO₄)₂(AsO₃OH)₃(2), were synthesized under hydrothermal conditions. They represent previously unknown structure types and are the first compounds synthesized in the systems SrO/BaO-CuO-As₂O₅-H₂O. Their crystal structures were determined by single-crystal X-ray diffraction [space group C2/c, a=18.536(4) Å, b=5.179(1) Å, c=24.898(5) Å, β=93.67(3)°, V=2344.0(8) Å³, Z=4 for 1; space group P4₂/n, a=7.775(1) Å, c=13.698(3) Å, V=828.1(2) Å³, Z=2 for 2]. The crystal structure of 1 is related to a group of compounds formed by Cu²⁺-(XO₄)³⁻ layers (X=P⁵⁺, As⁵⁺) linked by M cations (M=alkali, alkaline earth, Pb²⁺, or Ag⁺) and partly by hydrogen bonds. In 1, worth mentioning is the very short hydrogen bond length, D···A=2.477(3) Å. It is one of the examples of extremely short hydrogen bonds, where the donor and acceptor are crystallographically different. Compound 2 represents a layered structure consisting of Cu₂O₈ centrosymmetric dimers crosslinked by As1φ₄ tetrahedra, where φ is O or OH, which are interconnected by Ba, As2 and hydrogen bonds to form a three-dimensional network. The layers are formed by Cu₂O₈ centrosymmetric dimers of CuO₅ edge-sharing polyhedra, crosslinked by As1O₄ tetrahedra. Vibrational spectra (FTIR and Raman) of both compounds are described. The spectroscopic manifestation of the very short hydrogen bond in 1, and ABC-like spectra in 2 were discussed.     

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.     

Combinatorial topology of uranyl molybdate sheets: syntheses and crystal structures of (C6H14N2)3[(UO2)5(MoO4)8](H2O)4 and (C2H10N2)[(UO2)(MoO4)2]

Two new mixed organic-inorganic uranyl molybdates, (C₆H₁₄N₂)₃[(UO₂)₅(MoO₄)₈](H₂O)₄ (1) and (C₂H₁₀N₂)[(UO₂)(MoO₄)₂] (2), have been obtained by hydrothermal methods. The structure of 1 [triclinic, , Z=1, a=11.8557(9), b=11.8702(9), c=12.6746(9) Å, α=96.734(2)°, β=91.107(2)°, γ=110.193(2)°, V=1659.1(2) Å] has been solved by direct methods and refined on the basis of F² for all unique reflections to R1=0.058, which was calculated for the 5642 unique observed reflections (|F_o|?4σ_F). The structure contains topologically novel sheets of uranyl square bipyramids, uranyl pentagonal bipyramids, and MoO₄ tetrahedra, with composition [(UO₂)₅(MoO₄)₈]⁶⁻, that are parallel to (−101). H₂O groups and 1,4-diazabicyclo [2.2.2]-octane (DABCO) molecules are located in the interlayer, where they provide linkage of the sheets. The structure of 2 [triclinic, , Z=2, a=8.4004(4), b=11.2600(5), c=13.1239(6) Å, α=86.112(1)°, β=86.434(1)°, γ=76.544(1)°, V=1203.14(10) Å] has been solved by direct methods and refined on the basis of F² for all unique reflections to R1=0.043, which was calculated for 5491 unique observed reflections (|F_o|?4σ_F). The structure contains topologically novel sheets of uranyl pentagonal bipyramids and MoO₄ tetrahedra, with composition [(UO₂)(MoO₄)₂]²⁻, that are parallel to (110). Ethylenediamine molecules are located in the interlayer, where they provide linkage of the sheets. All known topologies of uranyl molybdate sheets of corner-sharing U and Mo polyhedra can be described by their nodal representations (representations as graphs in which U and Mo polyhedra are given as black and white vertices, respectively). Each topology can be derived from a simple black-and-white graph of six-connected black vertices and three-connected white vertices by deleting some of its segments and white vertices.     

Syntheses and crystal structures of two new hydrated borates, Zn8[(BO3)3O2(OH)3] and Pb[B5O8(OH)]·1.5H2O

Two new hydrated borates, Zn₈[(BO₃)₃O₂(OH)₃] and Pb[B₅O₈(OH)]·1.5H₂O, have been prepared by hydrothermal reactions at 170 °C. Single-crystal X-ray structural analyses showed that Zn₈[(BO₃)₃O₂(OH)₃] crystallizes in a non-centrosymmetric space group R32 with a=8.006(2) Å, c=17.751(2) Å, Z=3 and Pb[B₅O₈(OH)]·1.5H₂O in a triclinic space group P1¯ with a=6.656(2) Å, b=6.714(2) Å, c=10.701(2) Å, α=99.07(2)°, β=93.67(2)°, γ=118.87(1)°, Z=2. Zn₈[(BO₃)₃O₂(OH)₃] represents a new structure type in which Zn-centered tetrahedra are connected via common vertices leading to helical ribbons _∞¹[Zn₈O₁₅(OH)₃]¹⁷⁻ that pack side by side and are further condensed through sharing oxygen atoms to form a three-dimensional _∞³[Zn₈O₁₁(OH)₃]⁹⁻ framework. The boron atoms are incorporated into the channels in the framework to complete the final structure. Pb[B₅O₈(OH)]·1.5H₂O is a layered compound containing double ring [B₅O₈(OH)]²⁻ building units that share exocyclic oxygen atoms to form a two-dimensional layer. Symmetry-center-related layers are stacked along the c-axis and held together by interlayer Pb²⁺ ions and water molecules via electrostatic and hydrogen bonding interactions. The IR spectra further confirmed the existence of both triangular BO₃ and OH groups in Zn₈[(BO₃)₃O₂(OH)₃], and BO₃, BO₄, OH groups as well as guest water molecules in Pb[B₅O₈(OH)]·1.5H₂O.     

Hydro(solvo)thermal synthesis and structural characterization of a new organically templated gallophosphate: [H3N(CH2)2NH3]1/2·[Ga5 (PO4)4(OH)4]

A new three-dimensional open-framework gallophosphate: [H₃N(CH₂)₂NH₃]_1/2·[Ga₅ (PO₄)₄(OH)₄] has been prepared by hydro(solvo)thermal synthesis in presence of ethylenediamine (en) as structure-directing agent. Its structure was determined by means of single-crystal X-ray diffraction analysis with the following crystal data: monoclinic space group C2/m, a=10.1604(9) Å, b=12.0085(15) Å, c=7.1892(7) Å, β=90.797(6)°, V=877.08(16) Å³, Z=2, R₁=0.0264, wR₂=0.0764. The total numbers of measured reflections and unique reflections were 3508 and 1300, respectively. It is built up from a new secondary building unit (SBU) Ga₄P₄O₂₀(OH)₄, in which Ga atoms exhibit distorted trigonal bipyramidal coordination and P atoms are in tetrahedral coordination. The SBU Ga₄P₄O₂₀(OH)₄ are linked into a layer by bridge oxygen atoms. The GaO₄(OH)₂ octahedra link the layers into a three-dimentional framework. Diprotonated ethylenediamine was found in the channel of the framework. The material was characterized by IR spectroscopy, ¹H NMR spectra, thermogravimetric and differential thermal analyses and elemental analysis.     

Synthesis and crystal structure of new layered BaNaSc(BO3)2 and BaNaY(BO3)2 orthoborates

Crystals of two new layered BaNaSc(BO₃)₂ (I) and BaNaY(BO₃)₂ (II) orthoborates are grown from the melt-solution by the spontaneous crystallization onto the platinum loop. Single crystal X-ray analysis showed that the compounds are isostructural with the space group R3¯, a=5.23944(12) and 5.3338(2) Å, and c=34.5919(11) and 35.8303(19) Å for I and II, respectively, Z=6. The distinctive feature of the structure is the close-packed composite anion-cation (Ba,Na)(BO₃) layers. The layers are combined into the base building packages of two types: {M³⁺[Ba²⁺(BO₃)³⁻]₂}⁺ and {M³⁺[Na⁺(BO₃)³⁻]₂}⁻, where M is Sc or Y. Neutral-charge two-package (four-layer) blocks are stacked by the rhombohedral principle into twelve layers of the cubic packing.     

Hydrothermal synthesis, crystal structure, and magnetic properties of a novel organo-templated iron(III) borophosphate: (C3H12N2)Fe 6(H2O)4[B4P8O32(OH)8]

The organo-templated iron(III) borophosphate (C₃H₁₂N₂)Fe^III ₆(H₂O)₄[B₄P₈O₃₂(OH)₈] was prepared under mild hydrothermal conditions (at 443 K) and the crystal structure was determined from single crystal X-ray data at 295 K (monoclinic, P2₁/c (No. 14), a=5.014(2) Å, b=9.309(2) Å, c=20.923(7) Å, β=110.29(2)°, V=915.9(5) Å³, Z=2, R1=0.049, wR2=0.107 for all data, 2234 observed reflections with I>2σ(I)). The title compound contains a complex inorganic framework of borophosphate trimers [BP₂O₈(OH)₂]⁵⁻ together with FeO₄(OH)(H₂O)- and FeO₄(OH)₂-octahedra forming channels with ten-membered ring apertures in which the diaminopropane cations are located. The magnetization measurements confirm the Fe(III)-state and show an antiferromagnetic ordering at T_N≈14.0(1) K.