Single crystal growth and structural characterization of four complex uranium oxides: CaUO4, β-Ca3UO6, K4CaU3O12, and K4SrU3O12

Single crystals of complex uranium oxides, CaUO₄, β-Ca₃UO₆, K₄CaU₃O₁₂ and K₄SrU₃O₁₂ were grown from carbonate melts. The crystal structures of the four uranates were determined by single crystal X-ray diffraction. CaUO₄ crystallizes in the hexagonal space group R-3m, with lattice parameters a = 6.2570(7) Å and α = 36.04(2)°. The U⁶⁺ atom in CaUO₄ is 8-coordinate and exhibits hexagonal bipyramidal geometry with six long and two short U–O bonds, typical of a uranyl species. β-Ca₃UO₆ forms in the monoclinic space group P2₁/n, with lattice parameters a = 5.728(1) Å, b = 5.956(1) Å, c = 8.298(2) Å, and β = 90.55(3)°, and adopts a distorted double perovskite structure. K₄CaU₃O₁₂ and K₄SrU₃O₁₂ crystallize in the cubic space group Im-3m with lattice parameters a = 8.483(1) Å and a = 8.582(1) Å, respectively. In all three perovskite-type oxides, the U(VI) cation is located in an octahedral coordination environment and exhibits typical uranyl geometry with four long and two short U–O bonds.     

Serendipitous syntheses of the series Cs3Ln7Te12 (Ln = Sm,Gd, Tb): Compounds with large tunnels

Single crystals of Cs₃Ln₇Te₁₂ (Ln = Sm, Gd, Tb) have been grown accidentally through the reaction of Ln and Te with a CsCl or Cs₂Te₃ flux at elevated temperatures. The crystal structures have been determined from single crystal X-ray diffraction data. These compounds, which are isostructural with Rb₃Yb₇Se₁₂, crystallize in space group Pnnm of the orthorhombic system with two molecules in the following cells: Cs₃Sm₇Te₁₂, a=13.750(6), b=28.332(7), c=4.473(3) Å, T=293 K; Cs₃Gd₇Te₁₂, a=13.6064(13), b=28.209(3), c=4.4324(4) Å, T=153 K; Cs₃Tb₇Te₁₂, a=13.5708(16), b=28.116(3), c=4.4147(5) Å, T=153 K.     

Ligand-based luminescence in lead-containing complexes: The effect of conjugated organic ligands on fluorescence

The asymmetrically substituted heterocyclic alkyne 5-(pyridin-3-ylethynyl) picolinate (P3PA) was synthesized via a one-pot Sonogashira coupling. After purification, P3PA was reacted with Pb(NO₃)₂ into the two-dimensional coordination polymer Pb(P3PA)₂(H₂O)₂ (1) under hydrothermal conditions. Coordination polymer 1 crystallizes into the monoclinic space group I2/a, with a = 15.5775(10) Å, b = 5.9949(4) Å, c = 24.8380(16) Å, and β = 90.7500(10)°. In addition, the luminescent fluorene-based ligands, fluorene-9-carboxylate (FCA) and fluorenone-2,7-dicarboxylate (FDCA), were incorporated into hybrid materials via coordination to the lead (II) cation. Coordination polymer Pb(FCA)₂ (2) crystallizes in the monoclinic space group P2₁/c (a = 8.0518(9) Å, b = 25.338(3) Å, c = 10.5842(12) Å, β = 94.913(2)°), and forms a 1-D polymeric chain. Coordination polymer Pb₃(FDCA)₃(H₂O)₃ (3) crystallizes in the triclinic space group P1 (a = 6.6990(5) Å, b = 10.1529(7) Å, c = 13.6935(9) Å, α = 81.884(2)°, β = 87.260(2)°, γ = 84.399(2)°), and forms pillared 3-D layers. These three compounds have been identified via single crystal X-ray diffraction and characterized via powder X-ray diffraction, UV–Vis spectroscopy, and fluorescence spectroscopy.     

Single crystal growth and structural characterization of ternary transition-metal uranium oxides: MnUO4, FeUO4, and NiU2O6

Single crystals of MnUO₄, FeUO₄, and NiU₂O₆ were grown for the first time. The use of chloride fluxes facilitated the crystal growth. MnUO₄, a hexavalent uranium compound, crystallizes in the orthorhombic space group, Imma, with a = 6.6421(19) Å, b = 6.978(2) Å, and c = 6.748(2) Å, and exhibits typical uranyl, UO₂²⁺, coordination. FeUO₄ and NiU₂O₆ contain pentavalent uranium and are structurally related, exhibiting three-dimensional connectivity. FeUO₄ crystallizes in the orthorhombic space group, Pbcn, with a = 4.8844(2) Å, b = 11.9328(5) Å, c = 5.1070(2) Å. NiU₂O₆ crystallizes in the trigonal space group, P321, with a = 9.0148(3) Å, c = 5.0144(3) Å.     

Crystal structure,electronic structure and electrical conductivity of the antimony selenide BaLaSb2Se6

BaLaSb₂S₆ and BaLaSb₂Se₆ were prepared by heating the elements in the stoichiometric ratio under exclusion of air at 850 °C. Both chalcogenides adopt the KThSb₆Se₆ structure type, crystallizing in the space group P2₁/c (Z = 4) with a = 4.324(3) Å, b = 14.7057(16) Å, c = 15.910(2) Å, β = 92.741(3)°, Z = 4 for the sulfide and a = 4.4173(3) Å, b = 15.333(1) Å, c = 16.816(1) Å, β = 92.545(2)°, Z = 4 for the selenide. The structure of BaLaSb₂Se₆ is composed of ribbons of distorted SbSe₆ octahedra and Se₂^2? pairs. Electronic structure calculations show that the selenide is a semiconductor, in accord with the electrical conductivity measurement.     

Organic derivatives of tin (II/IV): Investigation of their structure

The structures of tin(II)-oxalate, tin(IV)Na–EDTA and tin(IV)Na₈-inositol hexaphosphate were investigated using XRD analysis. Samples were identified using the Mössbauer study, thermal analysis and FTIR spectrometry. The Mössbauer study determined two different oxidation states of tin atoms, and consequently two different tin surroundings in the end products. The tin oxalate was found to be orthorhombic with space group Pnma, a=9.2066(3) Å, b=9.7590(1) Å, c=13.1848(5) Å, V=1184.62 Å³ and Z=8. SnNa–EDTA was found to be monoclinic with space group P2₁/c₁, a=10.7544(3) Å, b=10.1455(3) Å, c=16.5130(6) Å, β=98.59(2)°, V=1781.50(4) Å³ and Z=4. Sn(C₆H₆Na₈O₂₄P₆) was found to be amorphous.     

Crystal structure and thermal analysis of the tetramethylammonium dichromate and trichromate

The structures of the tetramethylammonium dichromate, [(CH₃)₄N]₂Cr₂O₇ and trichromate, [(CH₃)₄N]₂Cr₃O₁₀, were determined from single-crystal X-ray diffraction data. These compounds crystallize in the orthorhombic system (space group Pnma, with Z=4 and a=17.192(1) Å, b=8.55(1) Å, c=10.637(1) Å), for the dichromate and in the monoclinic system (space group P2₁/n, with Z=4 and a=11.366(2) Å, b=8.493(2) Å, c=20.187(4) Å, β=103.98(3)° for the trichromate. The structures consist of discrete dichromate anions (Cr₂O₇)^2– or trichromate anions (Cr₃O₁₀)^2–, respectively, stabilized by quaternary ammonium [(CH₃)₄N]⁺. Phase transitions in [(CH₃)₄N]₂Cr₂O₇ have been evidenced by differential scanning calorimetry as well as a new allotropic variety of [(CH₃)₄N]₂Cr₂O₇ which was characterized by X-ray powder diffraction. It crystallizes in an orthorhombic system with the unit cell parameters a=24.49(1) Å, b=8.85(1) Å, c=8.705(8) Å.     

Crystal structure,physical properties and bond valence analysis of NaLuP2O7

Single crystals of a diphosphate NaLuP₂O₇ have been synthesized by the flux method and characterized by single-crystal X-Ray diffraction. NaLuP₂O₇ crystallizes in the monoclinic system with P2₁/n space group with cell parameters: a = 8.9985(8) Å, b = 5.3473(5) Å, c = 12.756(1) Å, β = 103.174° (1), V = 597.67 (9) Å³, Z = 4. Its structure consists of a three-dimensional framework of P₂O₇ units that are corner-shared by LuO₆ octahedra, forming tunnels running parallel to [010] which are occupied by Na atoms. NaLuP₂O₇ powder was characterized by XRD, SEM, FTIR and Raman spectroscopy. The activation energy of (1.49 eV) obtained by electrical measurements suggests the charge carriers to be the sodium cations. The activation energies obtained from impedance and loss spectra were analyzed in order to explain the mechanism of conduction. The correlation between ionic conductivity of NaLuP₂O₇ and its crystallographic structure was investigated and the most probable transport pathway model was determined.     

Controlled assembly of octa-track Ag-bpe chain-modified Wells–Dawson polyoxometalates

A new three-dimensional (3D) organic–inorganic hybrid compound based on the Wells–Dawson POMs modified by Ag(I) ions and bpe (bpe = bis(4-pyridyl)ethylene) molecules, {[Ag(C₁₂N₂H₁₀)]₃(H₃P₂W₁₈O₆₂)}·(C₁₂N₂H₁₀)·4H₂O, has been synthesized under hydrothermal condition and structurally characterized. Crystal data for the title compound: C₄₈H₅₁Ag₃N₈O₆₆P₂W₁₈, monoclinic, space group P2₁/m, a = 13.623(5) Å, b = 25.345(5) Å, c = 13.858(5) Å, α = 90°, β = 98.038(5)°, γ = 90°, V = 4738(3) Å³. It represents an important example of the family of Wells–Dawson POMs modified by M–N chains, in which Wells–Dawson POMs covalently link eight transitional metal complex fragments and represent the highest track number (8) of M–N chains modifying Wells–Dawson POMs. Furthermore, the electrochemical properties of the title compound were studied.     

Two tetravalent uranium silicate and germanate crystals with three membered single-ring by molten salt method: K2USi3O9 and Cs2UGe3O9

Two tetravalent uranium silicate and germanate M₂U^IVT₃O₉ (M = K, Cs; T = Si, Ge) crystals were crystalized under inert gas by molten salt flux growth method. K₂USi₃O₉ (1) crystallizes in the monoclinic space group P1₂₁/n1 with lattice parameters a = 7.1076 Å, b = 10.4776 Å, c = 12.2957 Å, γ = 120° and V = 915.67 Å³. Cs₂UGe₃O₉ (2) crystallizes in a hexagonal space group P-6 with lattice constants of a = 7.5138 Å, b = 7.5138 Å, c = 11.0114 Å, γ = 120° and V = 538.38 ų. Bond valence calculations indicate tetravalent uranium in both structures, which contain three-membered single-ring T₃O₉^6? trimers. K₂USi₃O₉ is the first uranium silicate that contains the Si₃O₉^6? trimers.     

Two new barium borate bromides: Ba2BO3Br and Ba3BO3Br3

Two new barium borate bromide crystals, Ba₂BO₃Br and Ba₃BO₃Br₃, have been obtained by spontaneous crystallization. Ba₂BO₃Br crystallizes in P−3m1 space group, with cell parameters of a = 5.5157(10) Å, c = 11.019(4) Å, and Z = 2, its structure is build up by alternately stacking along c-axis of [Ba₂(BO₃)₂]²⁻ layers and bromide [Ba₂Br₂]²⁺ layers. The solved structure is analog to Ba₂(BO₃)_1−x(CO₃)_xCl_1+x except the interstitial halogen atoms at (0, 0, 1/2) is missing and accordingly the partly CO₃ substitution for BO₃ has not been observed. Ba₃BO₃Br₃ crystallizes in a new structure type with P−1 space group and cell parameters of a = 9.280(4) Å, b = 9.349(7) Å, c = 13.025(9) Å, α = 92.71(3)°, β = 98.29(3)°, γ = 116.200(18)° and Z = 4. The basic structural unit in Ba₃BO₃Br₃ is the clusters composed of 4 BO₃ groups and 12 Ba atoms, which in turn are linked by eight Ba–O bonds with other four clusters to form sheets extend in the (001) plane.     

Two new organic–inorganic complexes associating the radical anion ABTS·– and the inorganic cation Ca2+: Ca0.55(ABTS)(H2O)x and Ca5(ABTS)6(H2O)29

The synthesis, crystal structure determination and physical properties of two new charge transfer salts containing the azinobisethylbenzothiazoline (ABTS) anion are described. Electrochemical oxidation in water of the diammonium salt of ABTS in presence of calcium chloride yields black single crystals of two new compounds with different morphologies. The needle-like crystals with Ca_0.55(ABTS)(H₂O)_x formula (x depending on the temperature) belong to the monoclinic symmetry, space group C2/c and cell parameters a=21.568(5), b=14.535(5), c=8.0278(17) Å, β=108.32(3)° at room temperature and a=22.180(4), b=14.288(3), c=8.0823(16) Å, β=108.13(3)°, with a lowering of the symmetry, space group Cc, at 200 K. The plate-shaped crystals formulated as Ca₅(ABTS)₆(H₂O)₂₉ belong also to the monoclinic symmetry with P2₁ space group and cell parameters a=11.222(2), b=37.991(8), c=19.327(4) Å, β=106.37(3)° at 200 K. The structure analysis of the first phase shows a one-dimensional character based on the stacking of organic molecules creating channels in which Ca²⁺ cations and water molecules are located. The second phase can be described as an alternation of organic and inorganic layers corresponding to a bidimensional hybrid network. The magnetic and electrical properties will be discussed.     

Synthesis,crystal growth and structure,magnetic and electrical properties of Ba4Ru2FeO10 and Ba4Ru2CoO10

Crystals of Ba₄Ru₂FeO₁₀ and Ba₄Ru₂CoO₁₀ (Cmca, Z = 4, Ba₄Ru₂FeO₁₀: a = 5.7899(1) Å, b = 13.2898(3) Å, c = 13.0098(4) Å, V = 1001.06 Å³; Ba₄Ru₂CoO₁₀: a = 5.7691(2) Å, b = 13.2061(3) Å, c = 12.9755(4) Å, V = 988.57 Å³) were obtained from binary oxides and BaCoO₃ at 1300 °C. Both compounds crystallize isostructural to Ba₄Ru₃O₁₀ with different preference of the 3d metal at the two crystallographic sites of Ru in the parent compound. Ba₄Ru₂FeO₁₀ exhibits a spin-glass like transition at 25 K, while Ba₄Ru₂CoO₁₀ does not show any magnetic order down to 2 K. According to electrical resistivity measurements performed on single crystals both compounds are semiconductors. In contrast to the variable-range hopping of the transport mechanism of Co bearing material, the electrical resistivity of Ba₄Ru₂FeO₁₀ follows an activation law resulting in a band gap of approximately 0.98 eV.     

Crystal growth of barium rhenates from hydroxide fluxes

Single crystals of two new barium rhenate compositions, Ba₁₆Re₆O₃₇ and Ba₁₀Re₃O₁₆(OH)₃, and of one new polymorph, orthorhombic Ba₅Re₂O₁₂, were grown out of a barium hydroxide flux in sealed silver tubes. Ba₁₆Re₆O₃₇ and Ba₁₀Re₃O₁₆(OH)₃ crystallize into the monoclinic C2/m system, with a = 20.577(4) Å, b = 5.8897(10) Å, c = 15.438 (3) Å, β = 92.255(10) ° and a = 1938342(9) Å, b = 5.8172(3) Å, c = 10.2925(5) Å, β = 91.7460(10) °, respectively. The orthorhombic polymorph of Ba₅Re₂O₁₂ crystallizes in the space group Pnma, with a = 19.6728(10) Å, b = 5.8491(3) Å and c = 10.4648(5) Å. All the three crystal structures are related and consist of a framework of BaO_x polyhedra (where x varies from six to twelve) with interpenetrating layers of ReO₆ octahedra.     

One-dimensional coordination polymers generated from an oxadiazole-containing N,N′-bipyridine-type ligand and inorganic salts

Three new one-dimensional coordination polymers have been prepared using Hg(II), Ag(I) and Zn(II) inorganic salts in combination with 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L6). The compounds were characterized by single crystal X-ray diffraction, IR spectroscopy, and elemental analysis. In the solid state, compounds 1 and 3 (1: monoclinic, P2₁/n, a=5.5373(3) Å, b=16.7839(9) Å, c=16.8120(9) Å, β=92.8610(10)°, V=1560.52(15) ų, Z=4; 3: monoclinic, P2₁/n, a=7.2958(4) Å, b=11.7214(6) Å, c=16.3979(9) Å, β=101.1150(10)°, V=1375.99(13) Å³, Z=4) feature novel one-dimensional helical chain motif. Compound 2, however, (2: monoclinic, P2₁/c, a=5.5506(4) Å, b=16.5895(12) Å, c=16.6871(11) Å, β=95.424(2)°, V=1529.70(19) ų, Z=4) exhibits one-dimensional zigzag chain motif, which result from the different conformations adopted by the L6 ligand and also the different metal coordination geometry. The luminescent properties of three new compounds were investigated in the solid state.     

Synthesis,characterization and properties of microporous lanthanide silicates: K8Ln3Si12O32NO3·H2O (Ln = Eu,Tb, Gd,Sm)

A family of microporous lanthanide silicates, K₈Ln₃Si₁₂O₃₂NO₃·H₂O (denoted LnSiO-CJ3, Ln = Eu, Tb, Gd, Sm), was synthesized under mild hydrothermal conditions at 503 K. The X-ray powder diffraction patterns of these compounds reveal that they are isostructural. The structure of EuSiO-CJ3 was determined by single-crystal X-ray diffraction analysis. It crystallizes in triclinic space group P-1 (No. 2) with a = 11.599(2) Å, b = 12.225(2) Å, c = 13.829(3) Å, α = 112.99(3)°, β = 92.05(3)°, γ = 90.57(3)°. The structure is based on [Si₃O₈]_n^4n? layers with 6-, 8-, 12-rings that are connected by EuO₆ octahedra to form a 3-D framework with 8-ring channels along the [001] direction. Charge neutrality is achieved by the K⁺ and NO₃^? ions located in the channels. The framework of EuSiO-CJ3 shows good thermal stability, which can be stable up to 1273 K. Ion-exchange capacity of EuSiO-CJ3 was investigated by the exchange of NO₃^? ions with halide ions (F^?, Cl^?, Br^?). The peaks in the emission spectra of LnSiO-CJ3 (Ln = Eu, Tb) belong to the characteristic transitions of Ln³⁺ (Ln = Eu, Tb) respectively. The lifetime measurements of LnSiO-CJ3 (Ln = Eu, Tb) suggest the presence of three Ln³⁺ (Ln = Eu, Tb) environments, which are consistent with the crystallographic results.     

Two coordination polymers of manganese(II) isophthalate and their preparation,structures, and magnetic properties

Two manganese coordination polymers, [Mn₂(ip)₂(dmf)]·dmf (1) and [Mn₄(ip)₄(dmf)₆]·2dmf (2) (ip=isophthalate; dmf=N,N-dimethylformamide), have been synthesized and characterized. X-ray crystal structural data reveal that compound 1 crystallizes in triclinic space group P?1, a=9.716(3) Å, b=12.193(3) Å, c=12.576(3) Å, α=62.19(2)°, β=66.423(17)°, γ=72.72(2)°, Z=2, while compound 2 crystallizes in monoclinic space group Cc, a=19.80(3) Å, b=20.20(2) Å, c=18.01(3) Å, β=108.40(4)°, Z=4. Variable-temperature magnetic susceptibilities of compounds 1 and 2 exhibit overall weak antiferromagnetic coupling between the adjacent Mn(II) ions.     

Synthesis,crystal structure,and magnetic properties of the oxometallates KBaMnO4 and KBaAsO4

Single crystals of KBaMnO₄ and KBaAsO₄ were grown using the hydroflux method and characterized by single crystal X-ray diffraction. Both compounds crystallize in the orthorhombic space group Pnma with a = 7.7795(4) Å, b = 5.8263(3) Å, and c = 10.2851(5) Å for the manganate and a = 7.7773(10) Å, b = 5.8891(8) Å, and c = 10.3104(13) Å for the arsenate. The materials exhibit a three-dimensional crystal structure consisting of isolated MnO₄³⁻ or AsO₄³⁻ tetrahedra, with the charge balance maintained by K⁺ and Ba²⁺. Each tetrahedron is surrounded by six K⁺ and five Ba²⁺, and shares its corner/edge with KO₁₀ polyhedra and corner/edge/face with BaO₉ polyhedra, respectively. The crystal growth, crystal structure and magnetic properties are discussed.