Refinement of the α-U4O9 crystalline structure: new insight into the U4O9 → U3O8 transformation

The oxidation reaction of UO(2) into U(3)O(8) is studied as a function of the crystalline distortion of interstitial oxygen clusters, named cuboctahedra, which appear in U(4)O(9) and U(3)O(7) intermediate phases. For that purpose, the refinement of α-U(4)O(9) was performed because this phase undergoes a trigonal distortion from cubic β-U(4)O(9) when the temperature is decreased. In α-U(4)O(9), the cuboctahedra can be described as crumpled sheets taken from a fragment of U(3)O(8). The manner by which the accumulation of crumpled sheets can lead to the formation of U(3)O(8) is discussed.     

CuCl─AlCl3─O2体系催化聚合噻吩的研究

研究了ＣｕＣｌ－ＡｌＣｌ３－Ｏ２催化体系用于噻吩开环聚合时的反应条件。并用ＩＲ、元素分析、Ｘ－射线衍射等方法对产物的结构进了分析，认为噻吩开环可形成聚丁二烯硫醚。     

Synthesis of New Solid Solutions on Neodymium-stabilized La2Mo2O9

Oxide ion conductors form a class of materials which are widely sought for and studied since they can be used in different field among solid oxide fuel cells (FOFC), oxygen sensors, oxygen pumping devices, or oxygen-permeable membrane catalysts, for instance1-3. Now research focuses on the oxide ion conductors with new structure and improving the conductivity or lowering the operating temperature. Recently P.Lacorre et al.4 have reported a novel oxide-ion conductor based on La2Mo2O9. F.…     

Synthesis, Crystal Structures and Characterization of Ba5LiTiNb9O30

A new niobate compound with the chemical composition of Ba5LiTiNb9O30 was synthesized by doping Li^ into the system BaO-TiO2-Nb2O5 in conventional solid state reaction method. The crystalline structure was determined by X-ray diffraction analysis (XRD). The results showed that crystal structure of Ba5LiTiNb9O30 belongs to tetragonal tungsten bronze structure with space group P4bm and its unit cell parameters: a=b=1.2512(2) nm, c=0.4008(5)nm. The microstructure of reaction products was observed by scanning electron microscopy (SEM).     

Chemical preparation and thermal behaviour of neodymium cyclotriphosphate tetrahydrate NdP3O9·4H2O

A new neodymium cyclotriphosphate tetrahydrate NdP₃O₉·4H₂O has been prepared using a classical method of aqueous chemistry and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG) and infrared spectroscopy which shows the characteristic bands of cyclotriphosphates as the triplet in the 1340–1260 cm⁻¹ area. The results of differential thermal analysis, X-ray powder diffraction and IR spectrum of the compound heated at different temperatures showed that, after dehydration, NdP₃O₉·4H₂O decomposes into an amorphous compound with a dehydration energy equals to 0.162 kJ g⁻¹, then it crystallises at 925 K in order to give the polyphosphate Nd(PO₃)₃.     

Effect of Glucose-lowering of Heteropolytungstogermanate β-K_6H[GeW_9V_3O_(40)]·9H_2O

IntroductionThe main abnormality in insulin- dependentdiabetes mellitus is heperglycemia due to thedeficiency of insulin. At present severe diabetescan be controlled only by dialy injections of insulin,so the development of some compounds that servethe function of insulin or as insulin mimetics onoral administration would be very helpful.The finding in 1 985 that vanadate ( + 5oxidation state of vanadium) shows an in vivoinsulin- like effect stimulated the research oninsulin- mimetic vanadium[…     

Synthesis,thermal behaviour and crystal structure of RbSrP3O9·3 H2O

Rubidium strontium cyclo-triphosphate trihydrate, RbSrP₃O₉·3 H₂O, was synthesized by reaction between cyclo-triphosphoric acid H₃P₃O₉ and rubidium and strontium carbonates. It crystallizes in the othorhombic system, space group Pnma, with a = 9.120(1) Å, b = 8.141(1) Å, c = 15.234(1) Å, V = 1 131.1(3) Å³, Z = 4. Crystal structure determination from single crystal data collected at 300 K shows that the P₃O₉ groups exhibit C_s symmetry and are not connected to each other. Rubidium (distorted octahedron) and strontium (distorted square antiprism) are coordinated by oxygen and water molecules yielding the formation of infinite chains interconnected to each other and to the P₃O₉ groups. The IR valence vibration bands of the P₃O₉ cycle have been identified in the domain 1 400–650 cm^–1 and related to the structural results. After water loss, the anhydrous phase crystallizes from an intermediate amorphous phase and further decomposes into Rb₂SrP₄O₁₂ and SrP₂O₆.     

High temperature characterization of the YBa2Cu3O9−y phase

We report the high temperature behaviour of single-phase YBa₂Cu₃O_{9 − y}. This compound reveals superconductivity above 90 K. We performed high temperature (20–960 °C) resistivity measurements, differential thermal analysis and thermogravimetric analysis investigations.It was found that substantial oxygen depletion occurred above 420°C. The oxygen content changed reversibly with temperature at ambient pressure. The second-order-like transition around 650 °C, observed by differential thermal analysis, is an orthorhombic-tetragonal rearrangement of the lattice. These results are important for optimizing the processing conditions of this new class of high T_c superconducting compounds.     

Synthesis,crystal structure and properties of tungstoantimonates with CuII or NiII sandwiched by two [ α -SbW9O33]9− or [ β -SbW9O33]9− subunits

Two sandwich-type tungstoantimonates K₄Na₂H₃[Na₂K(H₂O)₂{Cu(H₂O)}₃(α-SbW₉O₃₃)₂]?·?15H₂O (1) and Na₄H₄[{Ni(H₂O)₃}₂{W(OH)₂}₂{β-SbW₉O₃₃}₂]?·?23H₂O (2) were prepared from aqueous solution by different strategies. They were characterized by X-ray structure analysis, electrochemical analysis, EPR and IR spectroscopy. Both compounds are sandwich-like tungstoantimonates built from two B-[SbW₉O₃₃]^9? building blocks. The polyoxoanion of 1 consists of two trivacant B-α-[SbW₉O₃₃]^9? moieties linked by three Cu²⁺ ions leading to a Hervé-type sandwich framework. The polyoxoanion in 2 is composed of two isomeric B-β-[SbW₉O₃₃]^9? subunits joined together by two Ni²⁺ and two W⁶⁺ ions resulting in a Krebs-type sandwich structure.     

Study of ionic equilibria and computation of thermodynamic characteristics of heteropoly anion formation in GdW10O 36 9− solution

Interaction in GdW₁₀O ₃₆ ^9? -H⁺(OH^?)-H₂O system ( \(C_{GdW_{10} O_{36}^{9 - } } \) = 1 × 10^?3 mol/L) was studied by pH potentiometry at 25 ± 0.1°C, and a model that describes equilibrium processes in acid and alkaline regions was selected. Logarithms of concentrational and thermodynamic constants, values of Gibbs energy of monomeric ions reactions, and standard Gibbs energies of formation (ΔG _f ^o ) of heteropoly anions H _n GdW₁₀O ₃₆ ^(9?n)? and H _m GdW₅O ₁₈ ^(3?n)? were calculated. A series-parallel scheme of ion transitions was pro-posed, ion distribution diagrams in aqueous solutions were built, the regions of preferable anion content were found, and heteropoly salts were synthesized.     

Rotational isomerism of O,O′-dialkyl esters of phosphorodithioic acid

Compounds (RO)₂ P(:S)SH, RPrⁱ, Buⁿ, and Octⁿ, exhibit rotational isomerism about PO and PS bonds. Temperature-dependence studies of band intensities indicate values of ΔH for the equilibria between isomers to be 2.5 kJ mol⁻¹, RPrⁱ; 3.0 kJ mol⁻¹, RBuⁿ; and ∼4.5 kJ mol⁻¹, ROctⁿ.     

The Thermal Decomposition of Fe(NO3)3·9H2O

Using thermogravimetric analyses as well as isothermal gravimetric measurements, the thermal stability of the iron(III) nitrate nanohydrate has been determined. Several decomposition stages are the result of melting, evaporation and hydrolysis processes occurring in the salt—water system in the temperature range of 20–400°C. Some of the intermediates and the final product (-Fe₂O₃) are characterized by means of chemical analyses, X-ray diffraction patterns and IR spectra.This revised version was published online in November 2005 with corrections to the Cover Date.     

Thermal synthesis and characterization of Al χ La1-χ P3O9

New binary lanthanum-aluminum triphosphates were synthesized by thermal-condensation method from H₃PO₄, La₂O₃ and Al(OH)₃. These pigments could be potentially used as special inorganic pigments; their corrosion-inhibition properties were widely studied. Synthesis conditions were determined on the basis of DTA and TG measurements. The products were also characterized by X-ray diffraction analysis. Physical properties — density by pycnometric method, particle size distribution, oil number and critical pigment volume concentration (CPVC), pH and specific conductivity of their aqueous extracts were also determined.      

Two Polymorphs of the Inclusion Compound [（n-C4H9）4N] ＋（C13H9O3）-H2O

Two polymorphs of the inclusion compound [(n-C4H9)4N]+·(C13H9O3)-·H2O havebeen prepared and characterized by X-ray crystallography. Polymorph 1: triclinic P 1 , a =13.4982(2), b = 13.5743(2), c = 17.1996(2) , α = 67.045(1), β = 77.845(1), γ = 88.762(1)°, V =2830.43(7)3, Z = 4, R = 0.0491, wR = 0.1276; Polymorph 2: tetragonal P43, a = b = 13.53690(1) , c = 30.8491(8) , V = 5653.02(16)3, Z = 8, R = 0.0448, wR = 0.0984. In these two crystalstructures, the hydrogen-bonded ribbons built of 4,4 -dihydroxybenzophenone (DHBP, C13H10O3)anions and water molecules are orderly arranged to generate two-dimensional host layers, withtetrabutylammonium cations contained between the layers to form the sandwich-like inclusioncompounds. The structures of 1 and 2, which exist as two polymorphs, both display the similarpacking pattern and hydrogen-bond linking model.     

Synthesis and Spectroscopic Characterization of Organophosphoryl Polyoxotungstates α-A-[RP(O)]2PW9O5-34

Derivatized polyoxometalates(POMs), especially those including organic and organometallic components, have received current attention due to their potential application in catalysis, medicine and material sciences[1].     

Effects of Electronic Structure of Adjacent Carbon on the Strength of C─F⋯H─F Organofluorine Hydrogen Bonds

We investigate the effects of the electronic structure of carbon atom on the organofluorine hydrogen bonds, C─F⋯H─F. Our results show that we can modulate the strength of organofluorine hydrogen bonds by adjusting the volume of fluorine atom in C─F via changing the electronic structure of adjacent carbon atoms. Different with the conventional hydrogen bonds, we found that instead of carbon rehybridization and hyperconjugative effects, the magnitude of fluorine atomic volume plays important roles in determining the strength of the C─F⋯H─F organofluorine hydrogen bonds. The lone pair electrons at both the proximal and the vicinal carbon dramatically reinforce the strength of C─F⋯H─F organofluorine hydrogen bond with its interaction energy in the range of about 15–25 kcal/mol, that is, the carbanion-mediated organofluorine hydrogen bond could be very strong. Due to the high electronegativity of fluorine atom, it easily attracts the excess electron from the proximal and vicinal carbon, which results in the increase of its volume and negative charge. The enhanced volume of fluorine atom gives rise to the large polarization energy, and its enhanced negative charge favors the large electrostatic interaction, both of which substantially contribute to making the organofluorine hydrogen bonds strong. © 2019 Wiley Periodicals, Inc.     

Chemical Preparation,Thermal Behavior,Kinetic, and IR Studies of MnK4(P3O9)2.2H2O,Crystallographic Data of a New Cyclotriphosphate MnK4(P3O9)2, and Quantum Chemical Calculations for the P3O3− 9 Ion

Abstract

Chemical presparation, thermal behavior, and infrared (IR) studies are discussed for the cyclotriphosphate MnK₄(P₃O₉)₂.2H₂O and its anhydrous form MnK₄(P₃O₉)₂. The total dehydration of MnK₄(P₃O₉)₂.2H₂O, between 200 and 550 °C, leads to its anhydrous form MnK₄(P₃O₉)₂. MnK₄(P₃O₉)₂ is a new cyclotriphosphate crystallizing in the rhombohedral system and is stable until its melting point at 560 °C. The thermal behavior of MnK₄(P₃O₉)₂.2H₂O has been investigated and interpreted by comparison with IR absorption spectrometry and X-ray diffraction experiments. Two different methods, Ozawa and KAS (Kissinger-Akahira-Sunose), were selected in studying the kinetics of thermal behavior of the title compound. Quantum chemical calculations were made for the P₃O ^3? ₉ ion.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT     

K9TaW11O40.15H2O的合成及性质

迄今为止,有关钨钽杂多阴离子的报道极少。由于杂多酸在石油化工、颜料等领域有重要用途,人们对研究新的杂多阴离子的合成一直有着浓厚兴趣,也是杂多酸化学的重要内容。本文报道粉状白钨酸和可溶性钽酸钾溶液反应以合成十二聚系列的钨钽酸钾化合物。 钽酸钾按文献[1]制备,以Ta_2O_5(99.9%)与K_2CO_3之比1∶2的混合物于970℃熔融后     

Synthesis and Study of Tetraamminenickel 9-Molybdomanganate [Ni(NH3)4] · H4[MnMo9O32] · 6H2O

Tetraamminenickel 9-molybdomanganate [Ni(NH₃)₄] · H₄[MnMo₉O₃₂] · 6H₂O (zbdI) has been synthesized and studied by thermogravimetry, IR spectroscopy, and X-ray powder diffraction analysis. The crystals of compound I are monoclinic: a = 11.5961 Å, b = 11.1609 Å, c = 8.7200 Å, β = 109.23°, V = 1065.59 ų, ρ_calcd = 3.067 g/cm³, Z = 1.