Hydrothermal synthesis and electrochemistry of a δ-type manganese vanadium oxide

A new manganese vanadium oxide containing double sheets of V₂O₅ layers has been synthesized hydrothermally in the presence of tetramethylammonium ions. It has the electrochemically active δ-V₂O₅ structure, variants of which are found in V₆O₁₃ and xerogel vanadium oxides. The manganese ions, together with the N(CH₃)₄ ions, reside in a disordered manner between the oxide sheets. The δ-type [N(CH₃)₄]_zMn_yV₂O₅·nH₂O has a monoclinic structure, a=11.66(2) Å, b=3.610(9) Å, c=13.91(4) Å, β=108.8(2)°. It reacts readily with lithium with a capacity exceeding 220 mAh g⁻¹; the organic ions do not impede reaction as in the single sheet V₂O₅ materials, such as N(CH₃)₄V₃O₇.     

A novel interpenetrating 2-D brush-like structure: hydrothermal synthesis and crystal structure of [Cu(phen)V4O10]∞ (phen=1,10-phenanthroline)

A novel vanadium oxide, [Cu(phen)V₄O₁₀]_∞ (1), has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR, EPR spectroscopy and thermal analysis. The compound crystallizes in monoclinic structure of P2₁/m with a=7.4169(10) Å, b=10.0460(13) Å, c=11.0845(15) Å, β=102.520(2)°, V=806.27(19) Å³ and Z=2.     

Hydrothermal synthesis and electrochemistry of a manganese vanadium oxide, γ-MnV2O5

A new manganese vanadium oxide MnV₂O₅ has been synthesized using a mild hydrothermal reaction. MnV₂O₅ crystallizes in the orthorhombic system, space group Pnma, a=9.7585(2) Å, b=3.5825(1) Å, c=11.2653(2) Å. It is isostructural to γ-LiV₂O₅. It reacts readily and reversibly with lithium, with a stable capacity but with a large polarization.     

The layer crystal structure of [In2(C2O4)3(H2O)3]·7H2O and microstructure of nanocrystalline In2O3 obtained from thermal decomposition

A new indium oxalate, [In₂(C₂O₄)₃(H₂O)₃]·7H₂O, with a layered structure has been synthesised from precipitation methods at room temperature. It crystallises with a monoclinic symmetry, space group P2₁/c (No. 14), a=8.7456(1) Å, b=11.1479(2) Å, c=21.9376(4) Å, β=112.1(1)°, V=1979.98(6) ų and Z=4. The structure is built from neutral [In₂(C₂O₄)₃(H₂O)₃] corrugated layers, between which water molecules are intercalated. The layers are built from chains with two different sequences of indium atoms and bichelating oxalate groups. Two independent indium atoms are present in the structure with two coordination polyhedra, i.e., InO₈ as a distorted square-based antiprism and InO₇ as a nearly regular pentagonal-based bipyramid. The thermal decomposition has been studied in situ by temperature dependent X-ray diffraction and thermogravimety. The final product is nanocrystalline indium oxide. The microstructure of the oxide has been characterised with both the Voigt/Langford method based on the integral breadth and the whole pattern fitting approach. The size of the isotropic crystallites increases from 322 to 924 Å, while microstrains decrease, in the annealing temperature range 500–750 °C.     

Synthesis, Spectral, Thermal and CO2 Absorption Studies on Birnessites Type Layered MnO6 Oxide

Birnessite type layered MnO₆ oxides with increased crystallinity were synthesized from six carbohydrates and three dihydric phenols viz., dextrose, starch, fructose, galactose, maltose, lactose, catechol, resorcinol, quinol and KMnO₄ through the formation of a sol–gel. All of the MnO₆ oxides were characterized by powder XRD. The strong signal at 2θ ~ 12° corresponding to 7.4 Å refers to the Mn–Mn distance between the adjacent layers. The interlayer volume is dispersed with K⁺ ions and H₂O molecules. The presence of interlayer K⁺ ions is indicated by a signal at 25°, corresponding to a distance of 3.5 Å. IR spectra of the oxides show signature bands at ca. 500 cm^?1 due to the stretching modes occurring for MnO₆ entity. A broad band observed at ca. 3300 cm^?1 is due to interlayer water molecules. Thermal analysis indicated three stage decomposition with the formation of MnO₂ at ca. 600 °C through the intermediate formation of Mn(OH) _n . The MnO₆ exhibited a remarkable CO₂ scrubbing ability, which has also been investigated.     

Structural aspects of the metal-insulator transitions in V0.985Al0.015O2

The crystal structure of V_0.985Al_0.015O₂ has been refined from single-crystal X-ray data at four temperatures. At 373°K it has the tetragonal rutile structure. At 323°K, which is below the first metal-insulator transition, it has the monoclinic M₂ structure, where half of the vanadium atoms are paired with alternating short (2.540 Å) and long (3.261 Å) V-V separations. The other half of the vanadium atoms form equally spaced (2.935 Å) zigzag V chains. At 298°K, which is below the second electric and magnetic transition, V_0.985Al_0.015O₂ has the triclinic T structure where both vanadium chains contain V-V bonds, V(1)-V(1) = 2.547 Å and V(2)-V(2) = 2.819 Å. At 173°K the pairing of the V(1) chain remains constant: V(1)-V(1) = 2.545 Å, whereas that of the V(2) chain decreases: V(2)-V(2) = 2.747 Å. From the variation of the lattice parameters as a function of temperature it seems that these two short V-V distances will not become equal at lower temperatures. The effective charges as calculated from the bond strengths at 298 and 173°K show that a cation disproportionation has taken place between these two temperatures. About 20% of the V⁴⁺ cations of the V(1) chains have become V³⁺ and correspondingly 20% of the V⁴⁺ cations of the V(2) chains have become V⁵⁺. This disproportionation process would explain the difference between the two short V-V distances. Also it would explain why the T → M₁ transition does not take at lower temperatures.     

K2[Te4O8(OH)10]: synthesis,crystal structure and thermal behavior

Dipotassium octaoxodecahydroxotetratellurate, K₂[Te₄O₈(OH)₁₀], has been prepared hydrothermally in acidic medium under autogenous pressure. It crystallizes in space group P2₁/c of the monoclinic system with Z=2 in a cell of dimensions a=5.592(1) Å, b=8.283(2) Å, c=16.255(3) Å, and β=99.62(3)°. The outstanding feature of the structure is a tetrameric [Te₄O₈(OH)₁₀]^2– anion built up from edge and corner sharing TeO₆ octahedra. These anions and K⁺ cations are held together by electrostatic interactions and by hydrogen bonds. The compound decomposes in two steps at 350 and 420 °C, corresponding to a water and an oxygen loss, respectively, and affording the mixed valence oxide K₂Te^VI₃Te^IVO₁₂.     

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.     

New hydrogen-bonded dimeric and polymeric gold(I) complexes of the heterodifunctional ligand Ph2PNHP(O)Ph2

The preparation of several new gold(I) complexes by chloride metathesis of [AuCl(HL)] [HL=Ph₂PNHP(O)Ph₂] with either HL or K[Ph₂P(E)NP(E)Ph₂] (E=S or Se) is described. All compounds were characterised by a combination of ³¹P{¹H}, ¹H and IR spectroscopy, microanalysis and X-ray crystallography. X-ray structural studies reveal that [Au(HL)₂]Cl [monoclinic, space group P2₁/c, a=9.0726(3) Å, b=21.0847(6) Å, c=12.0131(3) Å, β=105.1090(10)°, V=2219 ų, Z=2, final R=3.97] forms a one dimensional polymeric structure in which alternating [Au(HL)₂]⁺ and Cl⁻ ions are linked through intermolecular N–H⋯Cl hydrogen-bonding. In contrast the three-co-ordinate compound [Au{Ph₂P(Se)NP(Se)Ph₂-Se,Se′}(HL)] [monoclinic, space group P2₁/a, a=21.6752(5) Å, b=9.1200(10) Å, c=24.0742(7) Å, β=106.080(2)°, V=4573 ų, Z=4, final R=8.94] forms hydrogen-bonded dimer pairs analogous to that previously observed in non-complexed HL. The X-ray crystal structure of the gold(I) precursor [AuCl(HL)] has also been determined: monoclinic, space group P2₁/c, a=10.217(8) Å, b=23.256(5) Å, c=20.086(5) Å, β=101.15(4)°, V=4683 ų, Z=8, final R=5.2. The X-ray crystal structure reveals intermolecular N–H⋯OP hydrogen-bonding between adjacent [AuCl(HL)] molecules forming infinite chains.     

Hydrothermal synthesis, structure and thermal property of a 2-dimensional network: sodium sulfate [Ni(H2O)6(NaSO4)2]

The title compound of [Ni(H₂O)₆(NaSO₄)₂] has been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction. The compound crystallizes in space group P2₁/c of the monoclinic system in a cell at 293.2 K of a=6.1820(12) Å, b=12.316(3) Å, c=9.0890(18) Å, β=106.03(3)°, and V=665.1(2) Å³. In the title compound, each SO₄ tetrahedron coordinates with three Na(I) ions and each Na(I) connects to three SO₄ tetrahedrons. Such a coordinate model makes up a two-dimensional network having two different kinds of rings and, in the bigger rings, the [Ni(H₂O)₆]²⁺ ions are located. In the solid state, some hydrogen bonds connect the title compound to form three-dimensional networks, stabilizing the crystal structure. Thermogravimetric analysis shows that there are three steps of weight loss from the beginning of 110 °C and the residue may be the mixtures of NiO₂ and Na₂O.     

Détermination de la structure cristalline du ferrite de baryum Ba2Fe6O11

The crystal structure of dibarium triferrite Ba₂Fe₆O₁₁ has been solved by direct methods, using intensity data collected by means of an automated diffractometer (MoKα radiation) and corrected for absorption. It crystallizes in the orthorhombic space group Pnnm: a = 23.024(10)Å, b = 5.181(3) Å, c = 8.900(4) Å, Z = 4. Program MULTAN was successfully used for locating Ba²⁺ and most of the Fe³⁺ ions. The structure was further refined by conventional Fourier and least-squares methods (full-matrix program) to a final R value of 0.045 for 1448 observed reflections. Fe³⁺ ions occur in both octahedral (FeO mean distance: 2.02 Å) and tetrahedral (FeO mean distance: 1.865 Å) coordination. Two types of Ba²⁺ ions are found, with six and seven neighboring oxygen atoms. The structure consists of sheets of edge-shared FeO₆ octahedra which are connected by means of corner-shared tetrahedra.     

Synthesis of diferrocenylmethoxyethanol via reaction of diferrocenylmethyl cabonium with glycol and its crystal structure

The new compound diferrocenylmethoxyethanol has been synthesized from the reaction of glycol in the presence of triethylamine with diferrocenylmethyl carbonium which was generated by diferrocenylmethanol treated with BF₃ in CH₂Cl₂ without separation from the reaction mixture. Diferrocenylmethoxyethanol was characterized by elemental analysis, ¹H NMR and IR. The structure was also confirmed by a X-ray single crystal study. It was found that diferrocenylmethoxylethanol crystallized in a monoclinic P2₁ space group and a=5.8250(8) Å, b=7.4034(10) Å, c=21.773(3) Å, α=90°, β=95.020(3)°, γ=90°, V=935.4(2) Å³, Z=2, D _c=1.577 mg·m^?3, μ=1.566 mm^?1, F(0 0 0)=460.     

Crystal structure and magnetic properties of a one dimensional complex oxide ca3nimno6

The results of structural refinements and magnetic properties of one-dimensional oxide Ca₃NiMnO₆ are presented. The structure of Ca₃NiMnO₆ was solved by Rietveld analysis of powder neutron date in space group R-3c with a=9.1227(9) Å, c=10.5811(17) Å, z=6 (type of K₄CdCl₆). Infinite chains of MnO₆ octahedra and (Ni,Mn)O₆ trigonal prisms sharing faces run parallel to the c axis. The chains are separated by Ca²⁺ cations, which are located in a distorted square antiprismatic environment. Magnetic susceptibility obeys the Curie-Weiss law at 300–600 K with μ_eff value 5.00 μ_B consistent with the valence cationic combination Ni²⁺-Mn⁴⁺. Magnetic measurements display the antiferromagnetic ordering in Ca₃NiMnO₆ at 16 K.     

Solvothermal Synthesis of a New Amine-Templated Vanadium Sulfate

A new organic-templated vanadium sulfate with formula [C₄H₁₂N₂][V^III (OH)(SO₄)₂] · H₂O 1 has been prepared under solvothermal conditions by using a mixture of glycol and water as solvent. The structure of this compound was characterized by IR, element analysis, TG and single crystal X-ray diffraction. The title compound crystallizes in the space group monoclinic, P2₁/c, a = 9.290(4) Å, b = 18.264(7) Å, c = 7.132(3) Å, β = 98.149(8)°,V = 1197.88 Å³, Z = 4. Structural analysis indicates that the title compound 1 possesses a 1D chain structure formed by VO₆ octahedra and SO₄ tetrahedra.     

Hydrothermal Synthesis and Characterization of a New Arsenic–Vanadium Compound with a β-[As<Subscript>8</Subscript>V<Subscript>14</Subscript>O<Subscript>42</Subscript>(SO<Subscript>4</Subscript>)]<Superscript>6−</Superscript> anion

A new arsenic vanadium compound (NH₄)₂[N(CH₃)₄]₄[β-As₈V₁₄O₄₂(SO₄)] 1 has been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, IR spectrum, elemental analysis and thermogravimetic (TG) analysis. Compound 1 crystallizes in monoclinic system with space group P2(1)/c, a = 11.4631(5) Å, b = 11.3539(5) Å, c = 24.6265(10) Å, β = 93.6620(10)°, V = 3198.6(2) ų, Z = 2, R1 = 0.0421 and wR2 = 0.1044. The molecule structural analysis reveals that compound 1 has a β-[As₈V₁₄O₄₂(SO₄)]^6? arsenic–vanadium cluster anion.     

Synthesis and crystal structure of a new cesium barium borate,CsBaB3O6

A new ternary borate oxide, cesium barium borate, CsBaB₃O₆, has been synthesized by solid-state reaction at 700 °C, and the single crystals were grown using CsF as a flux. The crystal structure has been determined by X-ray diffraction. It crystallizes in the trigonal space group P321 with a cell of dimensions a=12.469(3)Å, c=7.444(3)Å, α=90.00°, γ=120.00°, V=1002.3(5)ų, Z=6. The fundamental building units of CsBaB₃O₆ are the B₃O₆ plane hexagonal rings, which are parallel to each other and stack along the c-axis, and the Cs and Ba atoms alternately occupy sites between the B₃O₆ sheets. A comparison of the structures of CsBaB₃O₆, β-BaB₂O₄ and CsBO₂ is presented.     

Synthesis,structure, physical properties,and electronic structure of KGaSe2

The ternary gallium selenide KGaSe₂ has been synthesized by solid-state reactions and good quality crystal has been obtained. KGaSe₂ crystallizes in the monoclinic space group C2/c with cell dimensions of a = 10.878(2) Å, b = 10.872(2) Å, c = 15.380(3) Å, and β = 100.18(3)°. In the structure, adamantane like [Ga₄Se₁₀]⁸⁻ units are connected by common corners forming two-dimensional [GaSe₂]⁻ layers which are separated by K⁺ cations. KGaSe₂ exhibits congruent-melting behavior at around 965 °C. It is transparent in the range of 0.47–20.0 μm and has a band gap of 2.60(2) eV. From a band structure calculation, KGaSe₂ is a direct-gap semiconductor. The band gap is mainly determined by the [GaSe₂]⁻ layer.     

The molecular structure, bonding, and energetics of oxovanadium phthalocyanine: an experimental and computational study

A mass spectrometric study of saturated vapor over oxovanadium phthalocyanine showed the thermal stability and monomeric vapor composition of this compound. The molecular structure of oxovanadium phthalocyanine (VOPc) was determined using a combination of gas-phase electron diffraction (GED), mass spectrometry, and quantum chemical calculations. According to GED, the VOPc molecule has C_4v symmetry. Experimental structural parameters are in good agreement with the parameters obtained by UB3LYP/cc-pVTZ calculations. The vanadium atom has a five-coordinated square-pyramidal geometry, being shifted above the plane of the four isoindole nitrogen atoms by 0.576(14) Å. The parameters of the square pyramid VN₄ are r _h1(V–N) = 2.048(7) Å, r _h1(N···N) = 2.780(12) Å. The vanadium–oxygen bond length is r _h1(V–O) = 1.584(11) Å. NBO analysis shows polar character of coordination bonds with significant covalent contribution and pronounced direct donation. X-ray crystallography and GED give different coordination bond lengths according to the different physical meaning of the parameters obtained by these methods. The enthalpy of sublimation [?H _s ^o (593–678 K)] is 53.3 ± 0.8 kcal/mol.     

The sol–gel chromium-modified V<Subscript>6</Subscript>O<Subscript>13</Subscript> as a cathodic material for lithium batteries

A new V₆O₁₃-based material has been synthesized via the sol–gel route. This sol–gel mixed oxide has been obtained from an appropriate heat treatment of the chromium-exchanged V₂O₅ xerogel performed under reducing atmosphere. This new compound, with the chemical formula Cr_0.36V₆O_13.50, exhibits a monoclinic structure (C2/m) with the following unit cell parameters, a=11.89 Å, b=3.68 Å, c=10.14 Å, β=101.18°. The electrochemical characterization of this compound has been performed using galvanostatic discharge–charge experiments in the potential range 4–1.5 V and completed by ac impedance spectroscopy measurements. It exhibits a specific capacity of about 370 mAh g^?1, which makes the compound Cr_0.36V₆O_13.50 the best one in the V₆O₁₃-based system: 85% of the initial capacity (315 mAh g^?1) after the 35th cycle is still available at C/25 without any polarization. From impedance spectroscopy, a high kinetics of Li transport (D _Li=1.8×10^?9 cm² s^?1) is found at mid-discharge.