Synthese,Strukturuntersuchung und Reaktionen Phosphansubstituierter Derivate von Fe3(CO)9(μ3-CF)2

Syntheses, Structure Determination and Reactions of Phosphine Substituted Derivatives of Fe₃(CO)₉(μ₃-CF)₂ Photolysis of Fe₃(CO)₉(μ₃-CF)₂ 1 in the presence of acetonitrile 2a or benzoenitrile 2b results in the substitution of a single carbonyl ligand by a nitrile ligand yielding Fe₃(CO)₈(CH₃CN)(μ₃-CF)₂ 3a and Fe₃(CO)₈(C₆H₅CN)(μ₃-CF)₂ 3b, respectively. The acetonitrile ligand in 3a can be easily replaced by trimethyl-phosphine 4a or triphenylphosphine 4b . The monosubstituted compounds Fe₃(CO)₈(PR₃)(μ₃-CF)₂5, R = CH₃ a, R = C₆H₅, b are obtained as major products besides a small amount of the disubsituted products Fe₃(CO)₇(PR₃)₂(μ₃-CF)₂ 6. The structure of 5a has been elucidated by a single crystal X-ray structure determination. Thermal ligand substitution in 1, however, results in the formation of a mixture of mono-, disubstituted, and trisubstituted products, in which 6b is the major product for diphenylphosphine. 5a reacts with ethyne 7 forming a phosphine substituted diferra-allyl-cluster Fe₃(CO)₇(PR₃)(μ₃-CF)(μ₃? CF? CH? CH) 8. The structure of one isomere of 8 has been determinated by X-ray crystallography.     

Cu12As3VS16, eine neue Verbindung im System Sulvanit-Enargit

Cu₁₂As₃VS₁₆, a New Compound in the Sulvanite-Enargite System The compound Cu₁₂As₃VS₁₆ is formed by solid state reaction between Cu₃AsS₄ (enargite) and Cu₃VS₄ (sulvanite). The X-ray powder diagram shows a cubic pattern (a = 10.528 Å) but the compound exhibits a slight optical anisotropy. The specific resistivity of Cu₁₂As₃VS₁₆ is 10⁷ Ωcm, the Seebeck coefficient +390 μV/K. The i.r. spectrum has been measured. Mixed crystals and other compounds in the system enargite-sulvanite have not been observed.     

Na0.74Ta3O6, ein niedervalentes Oxotantalat mit einer Ta–Ta‐Mehrfachbindung

Na_0.74Ta₃O₆, a Low‐Valent Oxotantalate with Multiple Ta–Ta Bonds The title compound was prepared in a sealed tantalum tube through the reaction of Ta₂O₅, tantalum and Na₂CO₃ in a NaCl flux at 1570 K within 5 d. The crystal structure of Na_0.74Ta₃O₆ (a = 713.5(1), b = 1027.4(2), c = 639.9(1) pm, Immm, Z = 4) was determined by single crystal X‐ray means. The structure is isomorphous with NaNb₃O₅F [1]. The characteristic structural units are triply bonded Ta1₂ dumb‐bells with eight square‐prismatically co‐ordinated O ligands. Four Ta2, each octahedrally surrounded by O atoms, are side‐on bonded weakly to the binuclear Ta₂O₈ complex, thus forming a Ta₆ propellane‐like cluster. The lattice parameters of three additional M_xTa₃O₆ phases, M = Li, Mn, and Yb, are reported.     

Electrolytic production of metallic uranium from U3O8 in a 20-kg batch scale reactor</p> </p>

Summary The electrolytic reduction of U₃O₈ powder was carried out using LiCl-Li₂O molten salt in a 20-kg U₃O₈ batch cell to verify the feasibility of the process. As the current passes the cell, the decomposition of Li₂O and the reduction of U₃O₈ occur simultaneously in a cathode assembly and oxygen gas evolvs at the anode. The results from a 20-kg U₃O₈ scale cell were compared with data obtained from a bench scale cell. The results suggest a successful demonstration of this process, exhibiting a reduction conversion of U₃O₈ of more than 99% in a batch.</p> </p>     

Molecular structures of two unexpected metal complexes obtained from additions of coordinated phosphines to acetylenes

The syntheses and structures of two new compounds are reported. The first compound, [Cr(CO)₄]₂[C₄F₂(PPh₂)₄], obtained from Cr(CO)₄(PPh₂H)₂ and CF₃CCF₃ in the presence of one equivalent of BuLi has a structure with the ligand 1,2,3,4-tetrakis(diphenylphosphino)-1,4-difluorobutadiene chelating to two Cr(CO)₄ groups via the 1,4 and 2,3 phosphine groups. A mechanism for the formation of this compound is suggested which involves sequential deprotonation of a phosphine, nucleophilic attack on the fluorocarbon, and fluoride ion elimination. The second compound, CrC₃₆H₂₈P₂O₇, arises from a similar base promoted reaction of Cr(CO)₄-(PPhH₂)₂ and PhCCCOOEt. Here the expected initial product from cyclization of these reactants acts as a nucleophile to attack a second equivalent of the acetylene. The intermediate carbanion from this reaction can undergo a ring closure by displacement of OEt^-, giving the observed product.     

Ni添加对0.4Zr0.1V1.1Mn0.5Cr0.1合金的相结构和电化学性能的影响

本文通过XRD、SEM、EDS研究了Ti_0.4Zr_0.1V_1.1Mn_0.5Cr_0.1Ni_x(x=0，0.2，0.4，0.6，0.8)合金的相结构和电化学性能。该合金系由BCC结构的V基固溶体主相和六方结构的C14 Laves第二相组成，Ni能够促进第二相的生成，Ni含量的增加导致了各相中的化学组成和晶格参数的变化，并通过电化学方法研究了Ni含量对_0.4Zr_0.1V_1.1Mn_0.5Cr_0.1合金电极的最大放电容量、自放电性能、高倍率放电性能、循环稳定性能等的影响。     

A Chiral Gold Nanocluster Au20 Protected by Tetradentate Phosphine Ligands

The chirality of a gold nanocluster can be generated from either an intrinsically chiral inorganic core or an achiral inorganic core in a chiral environment. The first structural determination of a gold nanocluster containing an intrinsic chiral inorganic core is reported. The chiral gold nanocluster [Au₂₀(PP₃)₄]Cl₄ (PP₃=tris(2‐(diphenylphosphino)ethyl)phosphine) has been prepared by the reduction of a gold(I)–tetraphosphine precursor in dichloromethane solution. Single‐crystal structural determination reveals that the cluster molecular structure has C₃ symmetry. It consists of a Au₂₀ core consolidated by four peripheral tetraphosphines. The Au₂₀ core can be viewed as the combination of an icosahedral Au₁₃ and a helical Y‐shaped Au₇ motif. The identity of this Au₂₀ cluster is confirmed by ESI‐MS. The chelation of multidentate phosphines enhances the stability of this Au₂₀ cluster.     

Microencapsulation technology for thiourea corrosion inhibitor

The microencapsulation technology was brought in to solidify corrosion inhibitor in order to prolong the releasing time of it. In this work, thiourea (H₂NCSNH₂) was used as a corrosion inhibitor and microcapsuled using glutin and polyvinyl alcohol (PVA), respectively, as protective agent. The re-sealing process was used as a way to prolong the releasing time of the H₂NCSNH₂ encapsulated in microcapsules. It was found that the H₂NCSNH₂ microcapsule corrosion inhibitor using PVA as a protective agent had a better releasing time. The releasing times of the H₂NCSNH₂ microcapsule corrosion inhibitors were prolonged from 18 to 48 h by re-sealing process and using PVA as a protective agent. Both the use of PVA as a protective agent and the application of the re-sealing process decreased the encapsulation efficiency of the H₂NCSNH₂. The performance parameters on protecting Q235 carbon steel from corrosion in 0.1-M H₂SO₄ solution were evaluated by polarization curve and electrochemical impedance spectra methods. The results showed that the H₂NCSNH₂ released into the solution from microcapsules could well protect Q235 carbon steel from corrosion and the corrosion-inhibiting mechanisms of it were the same as that of H₂NCSNH₂.     

The non-centrosymmetric borate chlorides Ba2TB4O9Cl (T = Al,Ga)

The structures of the novel borate chlorides Ba₂TB₄O₉Cl (T = Al, Ga) have been determined by single crystal X-ray diffraction using crystals grown from a BaCl₂ flux. The compounds are isomorphous representatives of a new non-centrosymmetric tetragonal (P4₂nm) borate structure type related to triclinic hilgardite, Ca₂B₅O₉Cl·H₂O, and its orthorhombic anhydrous derivatives, such as Ba₂B₅O₉Cl. The Ba₂TB₄O₉Cl structure consists of a TB₄O₉ framework with Ba²⁺ and Cl⁻ ions accommodated in tunnels parallel to the c axis. The framework is based on a novel TB₄O₁₂ fundamental building block built of a tetraborate cluster of two BO₃ triangles and two BO₄ tetrahedra sharing a corner with a TO₄ tetrahedron. The large cross-sections of the tunnels within the framework are associated with Ba and Cl positional disorder. The measurement of the second harmonic generation efficiency (d_eff) for a powder sample of Ba₂GaB₄O₉Cl gave a value of 0.95 relative to a KH₂PO₄ standard.     

Die Leiterstruktur von LiNb6Cl19

The Ladder Structure of LiNb₆Cl₁₉ LiNb₆Cl₁₉ was obtained from a solid state reaction of Nb powder, NbCl₅, and Li₂C₂ at 530 °C. The structure was refined by single‐crystal X‐ray diffraction (space group Pmma (No. 51), Z = 2, a = 2814.6(1) pm, b = 687.35(5) pm, c = 641.39(3) pm). It contains edge and face bridging [NbCl₆] octahedra forming the motif of a ladder. The parallel alignment of ladders yields a one‐dimensional structure, with lithium ions occupying voids. Each ladder combines characteristic fragments from the niobium chloride structures NbCl₄, A₃Nb₂Cl₉ (A = Rb, Cs), and Nb₃Cl₈. The arrangement of niobium atoms in LiNb₆Cl₁₉ appears to be similar with trigonal niobium clusters obtained in the structure of Nb₃Cl₈. The electronic structures of niobium clusters in Nb₃Cl₈ and LiNb₆Cl₁₉ are compared with each other.     

Heterogeneous Ziegler‐Natta Catalyst Based on Neodymium for the Stereospecific Polymerization of Butadiene

The synthesis of a series of neodymium complexes supported on modified silica is reported. In an initial step the silanol groups were masked by a Lewis acid (BCl₃, AlCl₃, TiCl₄, ZrCl₄, SnCl₄, SbCl₅, HfCl₄), and then a soluble arene complex Nd(η⁶‐C₆H₅Me)(AlCl₄)₃ formed in situ was reacted with the modified silica. The supported complexes are active and highly stereospecific for butadiene polymerization; 1,4‐cis insertion is superior by 99%. The catalyst based on a treatment of silica with BCl₃ is the most efficient.     

Computerized modeling of intermediate compounds formed during thermal decomposition of gadolinium nitrate hydrate

It was shown that after partial dehydration occurs a simultaneous condensation of four mol of initial monomer Gd(NO₃)₃ · 6H₂O into a tetramer Gd₄O₄(NO₃)₄. The heterocycle containing 4 gadolinium atoms gradually loses N₂O₅ and, through the formation of unstable oxynitrates, is transformed into Gd₂O₃. The interatomic distances and angles were calculated using the molecular mechanics method. The comparison of the potential energies of consecutive oxyphosphates permitted an evaluation of their stability. The models of intermediate oxynitrates represent a reasonably good approximation to the real structures and a proper interpretation of experimental data.     

Über Ba2Ce0,75SbO6 – den ersten Vertreter einer weiteren Perowskitvariante

On Ba₂Ce_0,75SbO₆ – the First Representant of a Further Perovskite Variant The ochre coloured Ba₂Ce_0,75SbO₆ represents a perovskite variant with vacancies in the cationic lattice. The tetragonal cell dimensions are: a = 2×5,97₇ Å and c = 2×8,50₀ Å.     

Synthesis and thermal decomposition of bismuth peroxotitanate to Bi2Ti2O7

Bi-peroxotitanate was synthesized by a peroxo method and after thermal decomposition Bi₂Ti₂O₇ was obtained. DTA, TG and DSC curves of Bi₂[Ti₂(O₂)₄(OH)₆]5H₂O were recorded and used to determine isothermal conditions suitable for obtaining the intermediate samples corresponding to the phases observed during the thermal decomposition. The samples were identified by quantitative analysis, IR spectroscopy and X-ray analysis. The experimental results were used to propose a mechanism of thermal decomposition of the investigated compound to a nanosized Bi₂Ti₂O₇. The optimum conditions were also determined for obtaining Bi₂Ti₂O₇, which is applicable for piezosensors.     

Crystal Structure of [(C2H5)4N]4Cu7Cl14O2: A Cu14Cl28O4 8− Cluster

The synthesis and crystal structure of a novel copper(ll) halide cluster, (Et₄N)₈Cu₁₄Cl₂₈O₄, is reported. The cluster anion Cu₁₄Cl₂₈O₄ ^8? can be Viewed as being formed by the dimerization of two Cu₇Cl₁₄O₂ ^4? fragments. The hypothetical precursor anion of this latter cluster, Cu₇Cl₁₅O₂ ^5? in tum can be viewed as being formed from. the known parent Cu₇Cl₁₄O₂ ^4? cluster anions by fusion of pairs across a common CuCI₃ face. The fusion and dimenzation processes cause substantial distortion of the trigonal bipyramidal coordmation geometry of the copper(II) ions in the parent cluster. For three of the copper(II) ions this Yields a 4+1 geometry distinct from either trigonal blpyramldal or square pyramidal. The dimerization of the two Cu₇ clusters forces a severe distortion upon one additional copper(II) ion, this time towards a tetrahedral geometry. The implications of these distortions for the catalytic properties reactivities and magnetic behaviour of the parent complex are discussed.     

A P/N type compounded Cu<Subscript>2</Subscript>O/TiO<Subscript>2</Subscript> photo-catalytic membrane for organic pollutant degradation

A heterojunction thin film consisting of n-type titanium dioxide (TiO₂) and p-type cuprous oxide (Cu₂O) was fabricated on an FTO conducting glass. The TiO₂ films were grown on the FTO glass by sol–gel and spray pyrolysis methods, and Cu₂O was deposited on it via the hydrothermal method. The morphology, crystalline structure, and optical absorption characteristics were studied by scanning electron microscopy, X-ray diffraction, and ultraviolet–visible diffuse reflectance spectrum, respectively. The results show that the surface of the Cu₂O/TiO₂ film was composed of net and large grains, which contributed to a large specific surface area. The crystal phase of the TiO₂ in the Cu₂O/TiO₂ film remained anatase. The crystal phase of the Cu₂O could not be detected as it is found in traces. The Cu₂O/TiO₂ film had a stronger optical absorption ability than the pure TiO₂ film. To investigate catalytic activity, a photocatalytic degradation experiment of the Cu₂O/TiO₂ film was performed in a homemade thin-layer micro-reactor. The photocatalytic degradation of methylene blue increased with increasing amounts of deposited Cu₂O until a maximum limit was reached. The photocatalytic activity might have declined with an increase in Cu₂O content. The metallic oxide has the potential to screen other photocatalysts from the UV source.     

Camouflaging Structural Diversity: Co‐crystallization of Two Different Nanoparticles Having Different Cores But the Same Shell

Two ligand‐protected nanoscale silver moieties, [Ag₄₆(SPhMe₂)₂₄(PPh₃)₈](NO₃)₂ and [Ag₄₀(SPhMe₂)₂₄(PPh₃)₈](NO₃)₂ (abbreviated as Ag₄₆ and Ag₄₀, respectively) with almost the same shell but different cores were synthesized simultaneously. As their external structures are identical, the clusters were not distinguishable and become co‐crystallized. The occupancy of each cluster was 50 %. The outer shell of both is composed of Ag₃₂S₂₄P₈, which is reminiscent of fullerenes, and it encapsulates a well‐studied core, Ag₁₄ and a completely new core, Ag₈, which correspond to a face‐centered cube and a simple cube, respectively, resulting in the Ag₄₆ and Ag₄₀ clusters. The presence of two entities (Ag₄₀ and Ag₄₆ clusters) in a single crystal and their molecular formulae were confirmed by detailed electrospray ionization mass spectrometry. The optical spectrum of the mixture showed unique features which were in good agreement with the results from time‐dependent density functional theory (TD‐DFT).     

Crystal Structure and Magnetic Properties of a Hexanuclear Copper(II) Carboxylate

The synthesis and characterisation of the hexanuclear copper(II) carboxylate complex [Cu(O₂CCHPhOC₂H₄OC₂H₄OCH₃)₂]₆ ( 1 ) is described. Single‐crystal X‐ray structure analysis reveals that the copper(II) ions are arranged in a six‐membered ring which adopts a chair‐like conformation. The copper(II) ions are bridged by μ₂‐ and μ₃‐coordinating carboxylates. The magnetic behavior of 1 was measured between 2 and 300 K, revealing at low temperature a weak antiferromagnetic interaction. The χ_M(T) dependency was fitted mathematically with one coupling constant J₁ and a paramagnetic impurity α.     

Synthesis of Fe3O4, Fe2O3, Ag/Fe3O4 and Ag/Fe2O3 nanoparticles and their electrocatalytic properties

Two important iron oxides:Fe3O4 and Fe2O3,as well as Fe3O4 and Fe2O3 nanoparticles mingling with Ag were successfully synthesized via a hydrothermal procedure.The samples were confirmed and characterized by X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The morphology of the samples was observed by transmission electron microscopy(TEM).The results indicated Fe3O4,Fe2O3,Ag/Fe3O4 and Ag/Fe2O3 samples all were nanoparticles with smaller sizes.The samples were modified on a glassy carbon electrode and their elctrocatalytic properties for p-nitrophenol in a basic solution were investigated.The results revealed all the samples showed enhanced catalytic performances by comparison with a bare glassy carbon electrode.Furthermore,p-nitrophenol could be reduced at a lower peak potential or a higher peak current on a glassy carbon electrode modified with Ag/Fe3O4 or Ag/Fe2O3 composite nanoparticles.     

Verbindungen mit Schichtstrukturen in den Systemen CuGa5S8/CuIn5S8 und AgGa5S8/AgIn5S8

Compounds with Layered Structures in the Systems CuGa₅S₈/CuIn₅S₈ and AgGa₅S₈/AgIn₅S₈ The title systems have been investigated by single crystal and powder X‐ray diffraction methods on quenched samples. In the system AgGa_xIn_5–xS₈ spinel type phases are formed up to x < 2. A compound crystallising with a hexagonal layered structure is obtained for 2 < x ≤ 3. The crystal structure of this layered phase has been solved on a single crystal of composition AgGa₃In₂S₈: space group P6₃mc, Z = 2, a = 380.80 and c = 3076.4 pm. The structure is isotypic to the Zn₂In₂S₅ (II a) type. The sample AgGa₄InS₈ crystallises in a Wurtzite like structure with a = 377.25 and c = 616.1 pm. In the system CuGa_xIn_5–xS₈ a new compound with layered structure has been detected for 1 ≤ x ≤ 2 which crystallises hexagonally with a = 380.28 and c = 3073.4 pm (x = 2). For the spinel CuIn₅S₈ an exchange of In by Ga is not detected.