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.     

Synthesis and structural characterization of two new hexagonal osmates: Ba2Fe0.92Os1.08O6 and Ba2Co0.77Os1.23O6

Two complex oxides of osmium, Ba₂Fe_0.92Os_1.08O₆ and Ba₂Co_0.77Os_1.23O₆, have been prepared as single crystals from molten potassium hydroxide. Both oxides crystallize in the hexagonal space group P6₃mc with a = 5.7403(1) Å and c = 14.0771(6) Å and a = 5.7745(2) Å and c = 14.0946(7) Å for Ba₂Fe_0.92Os_1.08O₆ and Ba₂Co_0.77Os_1.23O₆, respectively. The structure of these compounds is related to the 6H–BaTiO₃ structure but exhibit mixed occupancy of both metals on the three crystallographically independent metal sites.     

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 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.     

The blue allotropic form of Co2+:Na2CoP2O7: optical and magnetic properties,correlation with crystallographic data

Na₂CoP₂O₇ is found in two allotropic forms. The first one is rose and belongs to the triclinic crystallographic system. The second one is blue and described in the orthorhombic system, space group Pna2₁, No. 33, with cell parameters a=15.378(6) Å, b=10.271(4) Å, c=7.713(2) Å and Z=8. A recent work showed that the orthorhombic phase could be considered as tetragonal: space group P4₂/mnm, No. 136 with a=7.706(1) Å and b=10.301(2) Å and Z=4. The optical and magnetic properties, particularly the EPR spectrum, of the divalent cobalt ion and their phenomenological simulation were of considerable help to complement the study and allowed us to specify the real structure.     

The mixed-valence iron compound Na0.1Fe7(PO4)6: crystal structure and 57Fe Mössbauer spectroscopy between 80 and 295 K

The crystal structure of the synthetic iron phosphate Na_0.10(1)Fe_6.99(1)(P_1.00(1)O₄)₆ has been refined at 270 and 100 K from single-crystal X-ray diffraction data. The compound is triclinic, P−1, Z=1, lattice parameters: a=6.3944(9) Å, b=7.956(1) Å, c=9.364(1) Å, α=105.13(1)°, β=108.35(1)°, γ=101.64(1)° at 270 K and adopts the well-known howardevansite structure type. Iron, being both in the divalent and the trivalent valence state, is ordered on the four symmetry non-equivalent iron positions [Fe²⁺ on Fe(1) and Fe(3), Fe³⁺ on Fe(2) and Fe(4)]. Three of the four iron positions show octahedral oxygen atom coordination, the fourth one, which is occupied by Fe²⁺, is five-fold coordinated. The structure consists of crankshafts (buckled chains) of edge sharing Fe-oxygen polyhedra, passing through the unit cell in [101] direction. Structural investigation at 100 K shows no change of symmetry. The valence state and distribution of iron was determined by ⁵⁷Fe Mössbauer spectroscopy. The compound shows 4 subspectra in agreement with the four different Fe sites. The assignment of the Fe²⁺ doublets to the Fe(1) and Fe(3) sites is trivial due to the 2:1 stoichiometry, also found in the Mössbauer spectra. For the Fe³⁺ sites, the temperature-dependent variation of structural distortion parameters and the quadrupole splitting led to a clear doublet assignment.     

Hybrid inorganic–organic frameworks containing magnesium: Synthesis and structures of magnesium squarate,diglycolate, and glutarate,and potassium magnesium cyclobutanetetracarboxylate

Four new magnesium containing metal–organic hybrid compounds have been synthesized in an effort to prepare low-density materials for hydrogen storage. The compounds were prepared hydrothermally and characterized using single crystal X-ray diffraction. Three of these compounds are analogs of known transition metal structures with squarate (I, Pn-3n, a = 16.276(5) Å), diglycolate (II, P2₁2₁2₁, a = 6.860(1) Å, b = 9.993(1) Å, c = 10.884(1) Å, R₁ = 0.0341), and glutarate (III, R-3, a = 10.744(2) Å, c = 28.677(5) Å, R₁ = 0.0554) ligands; the fourth is a novel structure using cyclobutanetetracarboxylate (IV, Pccn, a = 9.382(1) Å, b = 14.410(2) Å, c = 8.725(1) Å, R₁ = 0.0465) which contains potassium as well as magnesium cations.     

Synthesis,X-ray and optical characterizations of two new oxysulfides: LaInS2O and La5In3S9O3

Two new compounds, LaInS₂O and La₅In₃S₉O₃ were synthesized in the La–In–S–O quaternary system. Both compounds crystallize in the orthorhombic system with lattice constants a=20.5421(6) Å, b=14.8490(4) Å, c=3.9829(1) Å for LaInS₂O, and a=4.1018(1) Å, b=26.833(1) Å, c=16.023(1) Å for La₅In₃S₉O₃. The structure of La₅In₃S₉O₃ was solved from single-crystal X-ray data, in the space group Pbcm, with Z=4; it is built from three-atom-thick (100)_NaCl layers interleaved with fluorite-type ribbons, and is closely related to the structures of the known lanthanum and indium compounds La₁₀In₆S₁₇O₆ and La₄In₅S₁₃. Both compounds LaInS₂O and La₅In₃S₉O₃ exhibit a yellow color; measurement of their optical gaps gave 2.73 and 2.60 eV, respectively.     

Inhibitors for magnesium corrosion: Metal organic frameworks

Electrochemical measurements demonstrate that magnesium surfaces can be protected by alkyl carboxylate. In a nearly neutral pH solution of sodium decanoate, the reduced corrosion rate and a passivation behaviour are attributed to the formation of Mg(C₁₀H₁₉O₂)₂(H₂O)₃ (Mg(C10)₂) at the magnesium surface whereas heptanoate Mg(C₇H₁₃O₂)₂(H₂O)₃ (Mg(C7)₂) is not efficient in such media. The crystal structures of the two metal carboxylates Mg(C7)₂ and Mg(C10)₂ are determined by X-ray diffraction. Single crystal data: Mg(C7)₂, P2₁/a, a = 9.130(5) Å, b = 8.152(5) Å, c = 24.195(5) Å, β = 91.476(5)°, V = 1800.3(15) Å³, D_x = 1.242 g cm⁻³, Z = 4. Synchrotron powder data: Mg(C10)₂, P2₁/a, a = 9.070(3) Å, b = 8.165(1) Å, c = 32.124(1) Å, β = 98.39(1)°, V = 2353.85(8) Å³, D_x = 1.188 g cm⁻³, Z = 4. Their layered structures are quite similar and differ mainly by the length of the hydrophobic chains. They consist of two planes of O-octahedra centred by Mg atoms, parallel to (001). The distorted octahedra are constituted by three oxygen atoms from carboxylate groups and by three oxygen atoms coming from water molecules. The layers are connected by hydrogen bonds. The carboxylate chains are located perpendicularly and on both sides of these planes. One carboxylate chain is bridging the Mg atom along [010] while the other is monodendate. The presence of structural water is confirmed by thermal analyses.     

Synthesis and structure of a new scorpionate-dithio carboxyl oxovanadium complex and an organic dithio carboxyl compound

A new complex of oxovanadium(IV), V₂O₂[(HB(pz)₃)₂(pyrro)₂ (1) and a dimer-dithio carboxyl compound (C₅H₈NS₂)₂ (2) have been synthesized by the reaction of VOSO₄·nH₂O with NaHB(pz)₃ and pyrrolidine dithio carboxylic acid ammonium salt. They were characterized by element analysis, IR spectra, UV–vis spectra and X-ray diffraction. Structural analyses of 1 and 2 gave the following parameters: 1, triclinic, P-1, a = 7.732(4) Å, b = 14.285(8) Å, c = 17.802(9) Å, α = 101.314(8)°, β = 92.682(9)°, γ = 92.228(9)°, V = 1923.6(18) Å³, and Z = 4; 2, monoclinic, C2/c, a = 13.857(2) Å, b = 10.4213(18) Å, c = 9.436(2) Å, β = 97.099(2), V = 1352.1(4) Å³, and Z = 4. In complex 1, vanadium atom adopts a distorted tetragonal bipyramid structure, which is typical for oxovanadium(IV) complexes. Compound 2 is a dimer-dithio carboxyl compound with S–S bond. In addition, thermal analysis was performed for analyzing the stabilization of the complexes.     

Pressure–temperature phase diagram of SeO2. Characterization of new phases

We have investigated SeO₂ at high pressures and high temperatures. Two new phases (β-SeO₂ and γ-SeO₂) and the boundary separating them have been found, following experimental runs performed at pressures up to 15 GPa and temperatures up to 820°C. The two phases crystallize in the orthorhombic system in space group Pmc2₁ (no. 26) with a=5.0722(1) Å, b=4.4704(1) Å, c=7.5309(2) Å, V=170.760(9) Å³ and Z=4 for the β-phase, and with a=5.0710(2) Å, b=4.4832(2) Å, c=14.9672(6) Å, V=340.27(3) Å³ and Z=8 for the γ-phase. Both phases are stable at ambient pressure and temperature below −30°C. At ambient temperature the phases return to the starting phase (α-SeO₂) in a few days. We discuss our findings in relation to a previous report of in-situ measurements at high pressures and ambient temperature.     

Two metal-organic frameworks with infinite indium hydroxide chains connected through tetradentate carboxylate linkers

Two indium-based metal-organic framework have been hydrothermally synthesized by using 1,2,4,5-benzenetetracarboxylate (pyromellitate) or 3,3′,4,4′-benzophenonetetracarboxylate as linkers. Their structures have been characterized by means of single-crystal X-ray diffraction analysis and reveal closely related networks consisting of identical infinite chains of indium-centered trans-connected octahedra, linked to each other through the tetradentate carboxylate linkers. The structure of the indium pyromellitate (MIL-60) delimits a 3D frameworks with one-dimensional 4.0 × 2.7 Å² channels running along [001] encapsulating water. The second compound (MIL-119) is built up from the compact stacking of the 3,3′,4,4′-benzophenonetetracarboxylate molecules connected to four distinct inorganic chains. In the latter, water species are found to be trapped between two indium hydroxide chains or in terminal positions, bonded to the indium cations. Strong hydrogen interactions are observed between these types of water molecules. Both compounds do not exhibit any significant porosity.Crystal data: In₂(OH)₂[C₁₀O₈H₂]·2H₂O (MIL-60): monoclinic, C2/m, a = 7.1854(7) Å, b = 17.1940(17) Å, c = 6.5167(7) Å, β = 100.639(2)°, V = 791.27(14) Å³, Z = 2. In₂(OH)₂(H₂O)[C₁₇O₉H₆]·H₂O (MIL-119), monoclinic, P2₁/c, a = 14.2530(11) Å, b = 14.4024(10) Å, c = 11.7027(9) Å, β = 93.018(2)°, V = 2399.0(3) Å³, Z = 4.     

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.     

Crystal structures of Th(OH)PO4, U(OH)PO4 and Th2O(PO4)2. Condensation mechanism of MIV(OH)PO4 (M = Th,U) into M2O(PO4)2

Three new crystal structures, isotypic with β-Zr₂O(PO₄)₂, have been resolved by the Rietveld method. All crystallize with an orthorhombic cell (S.G.: Cmca) with a = 7.1393(2) Å, b = 9.2641(2) Å, c = 12.5262(4) Å, V = 828.46(4) Å³ and Z = 8 for Th(OH)PO₄; a = 7.0100(2) Å, b = 9.1200(2) Å, c = 12.3665(3) Å, V = 790.60(4) Å³ and Z = 8 for U(OH)PO₄; a = 7.1691(3) Å, b = 9.2388(4) Å, c = 12.8204(7) Å, V = 849.15(7) Å³ and Z = 4 for Th₂O(PO₄)₂. By heating, the M(OH)PO₄ (M = Th, U) compounds condense topotactically into M₂O(PO₄)₂, with a change of the environment of the tetravalent cation that lowers from 8 to 7 oxygen atoms. The lower stability of Th₂O(PO₄)₂ compared to that of U₂O(PO₄)₂ seems to result from this unusual environment for tetravalent thorium.     

Crystal structure and ionic conductivity of AgCr2(PO4)(P2O7)

Single crystals of a new phosphate AgCr₂(PO₄)(P₂O₇) have been prepared by the flux method and its structural and the infrared spectrum have been investigated. This compound crystallizes in the monoclinic system with the space group C2/c and the parameters are, a = 11.493 (3) Å, b = 8.486 (3) Å, c = 8.791 (2) Å, β = 114.56 (2)°, V = 779.8 (3) ųand Z = 4. Its structure consists of CrO₆ octahedra sharing corners with P₂O₇ units to form undulating chains extending infinitely along the [110] direction. These chains are connected by the phosphate tetrahedra giving rise to a 3D framework with six-sided tunnels parallel to the [101] direction, where the Ag⁺ ions are located. The infrared spectrum of this compound was interpreted on the basis of P₂O₇^4? and PO₄^3? vibrations. The appearance of ν_sP–O–P in the spectrum suggests a bent P–O–P bridge for the P₂O₇^4? ions in the compound, which is in agreement with the X-ray data. The electrical measurements allow us to obtain the activation energy of (1.36 eV) and the conductivity measurements suggest that the charge carriers through the structure are the silver captions.     

Synthesis,structure, and characterization of a new two-dimensional lead(II) vanadate,Ba3PbV4O14

A new two-dimensional lead(II) vanadate, Ba₃PbV₄O₁₄ has been synthesized by standard solid state techniques using BaCO₃, PbO, and V₂O₅ as reagents. The structure of Ba₃PbV₄O₁₄ was determined by single-crystal X-ray diffraction. Ba₃PbV₄O₁₄ crystallizes in the triclinic space group P-1 (no. 2), with a = 7.2997(15) (Å), b = 7.2932(15) (Å), c = 13.379(3) (Å), α = 93.68(3)°, β = 99.68(3)°, γ = 91.49(3)°, V = 700.2(2) (ų) and Z = 2. Ba₃PbV₄O₁₄ exhibits a novel two-dimensional layered structure consisting of corner shared VO₄ tetrahedra that are linked by edge shared PbO₇ polyhedra, in which the Ba²⁺ cations occupy the interlayer region. The Pb²⁺ cations are in asymmetric coordination environments attributable to its lone pair. Infrared, Raman, and UV–vis diffuse reflectance spectroscopy, thermogravimetric analysis, and dipole moment calculations are also presented.     

Helical chains of [MO5Cl] octahedra – Three compounds in the new family AEM2Te3O8Cl2 (AE = Ca,Sr and M = Co,Ni)

The compounds CaCo₂Te₃O₈Cl₂, SrCo₂Te₃O₈Cl₂ and SrNi₂Te₃O₈Cl₂ were synthesized via solid–gas reactions and investigated using single-crystal X-ray diffraction. While the compound CaCo₂Te₃O₈Cl₂ formed large enough single crystals to allow for a detailed structural analysis, crystals of the Sr-containing compounds yielded evidence that they are isostructural. CaCo₂Te₃O₈Cl₂ crystallizes in the monoclinic system, space group P2₁/c, a = 6.537(2) Å, b = 9.088(2) Å, c = 19.500(9) Å, β = 113.36(4)°, Z = 4. It exhibits [CoO₅Cl] helical chains along the [010] direction, connected by [CaO₈] polyhedra, [TeO₃E] tetrahedra and [TeO₄E] trigonal bipyramids (the lone pair of electrons on Te^IV is designated as E) to form a layer. The layers are held together only by weak van der Waals forces; the shortest interlayer distance is a Te?Cl contact of 3.432(4) Å.     

Copper and cadmium phosphonates based on 2-quinolinephosphonate

Hydrothermal reactions of 2-quinolinephosphonic acid (1) and CuSO₄ or CdSO₄ result in two new compounds with formula Cu(2-C₉H₆NPO₃) (2) and Cd(2-C₉H₆NPO₃)(H₂O) (3). Compound 2 has a layer structure in which dimers of edge-sharing {CuO₄N} square-pyramids are linked by {CPO₃} tetrahedra through corner sharing. Compound 3 shows a new type of layer structure where chains of corner sharing {CdO₅N} octahedra are connected by {CPO₃} tetrahedra into an inorganic layer. The quinoline groups fill in the inter-layer spaces in both cases. Crystal data for 1: monoclinic, space group P2₁/c, a = 10.270(2) Å, b = 13.566(3) Å, c = 6.9818(16) Å, β = 101.916(4)°, V = 951.8(4) Å³, Z = 4. For 2: monoclinic, space group P2₁/c, a = 13.976(3) Å, b = 7.9398(18) Å, c = 7.8687(18) Å, β = 101.150(5)°, V = 856.7(3) Å³, Z = 4. For 3: monoclinic, space group P2₁/c, a = 17.164(4) Å, b = 5.4870(12) Å, c = 10.850(2) Å, β = 101.557(4)°, V = 1001.1(4) Å³, Z = 4. The magnetic measurement on 2 reveals a dominant antiferromagnetic exchange coupling between the Cu(II) centers. A quasi-reversible electrochemical reaction is observed for complex 2 immobilized on the surface of GC electrode, corresponding to the redox couple Cu²⁺/Cu⁺. The fluorescent properties of 1–3 are also investigated.     

Real structure of SrSi2O2N2

SrSi₂O₂N₂ is an important host lattice for Eu²⁺ doped phosphors. Its crystal structure (space group P1, a = 7.0802(2) Å, b = 7.2306(2) Å, c = 7.2554(2) Å, α = 88.767(3)°, β = 84.733(2)°, γ = 75.905(2)° and V = 358.73(2) Å³, Z = 4) is isotypic with EuSi₂O₂N₂: highly condensed silicate layers are separated by Sr²⁺. The samples are characterized by pronounced real structure effects owing to pseudosymmetry of partial structures. Polysynthetic twinning with domains of various sizes is ubiquitous and oriented intergrowth of domains with different orientations has also been observed and analysed in detail by means of electron diffraction and high-resolution electron microscopy. These effects also affect the X-ray powder pattern and were taken into account in a Rietveld refinement.     

Two novel Keggin tungstocobaltates grafted by cobaltII complex group(s): K[Co(phen)2(H2O)]2[HCoW12O40]·2H2O and [Co(2,2′-bipy)3]1.5{[Co(2,2′-bipy)2(H2O)][HCoW12O40]}·0.5H2O

Two novel inorganic–organic hybrid compounds composed of Keggin tungstocobaltate framework and cobalt(II)–N coordination complexes, K[Co(phen)₂(H₂O)]₂[HCoW₁₂O₄₀]·2H₂O (1) (phen = 1,10-phenanthroline) and [Co(2,2′-bipy)₃]_1.5{[Co(2,2′-bipy)₂(H₂O)][HCoW₁₂O₄₀]·0.5H₂O (2) (bipy = bipyridine), have been synthesized under hydrothermal conditions by directly using Keggin POMs as starting materials, which were characterized by elemental analyses, IR, TG analyses and X-ray single crystal diffraction. Crystal data for compound 1: C₄₈H₄₁Co₃KN₈O₄₄W_12, triclinic, space group P-1, a = 10.918(5) Å, b = 13.401(5) Å, c = 13.693(5) Å, α = 69.291(5)°, β = 71.568(5)°, γ = 78.421(5)°, V = 1768.9(12) Å³, Z = 1; for compound 2: C₁₃₀H₁₀₄Co₇N₂₆O₈₃W_24, orthorhombic, space group, C2/c, a = 46.839(9) Å, b = 14.347(3) Å, c = 26.147(5) Å, α = β = γ = 90°, V = 17,570(6) Å³, Z = 4. Compound 1 exhibits a pseudo-1D chainlike structure, in which potassium ions act as linkages of Keggin unit doubly grafted by [Co(phen)₂(H₂O)] complex. Compound 2 represents a [Co(2,2′-bipy)₂(H₂O)]²⁺ mono-grafted Keggin tungstocobaltate derivative with 1.5[Co(2,2′-bipy)₃]²⁺ countercations. The cyclic voltammetric behavior of 1-CPE is similar to the parent 3-CPE, but the cyclic voltammetric behavior of Co^II shows a little difference. Variable-temperature magnetic susceptibility measurement of compound 1 demonstrates the presence of antiferromagnetic interactions.