Synthese und Kristallstruktur von [Fe(MeCN)6][Fe2OCl6]

Synthesis and Crystal Structure of [Fe(MeCN)₆][Fe₂OCl₆] [Fe(MeCN)₆][Fe₂OCl₆] ( 2 ) is obtained by passing dry air through a solution of FeCl₂ in acetonitrile in almost quantitative yield. 2 crystallises in the trigonal space group R 3 [a = b = 12.121(1), c = 29.875(6) Å, Z = 6]. The oxygen atom in the Fe₂OCl₆ anion occupies the 3 position and causes therefore an Fe–O–Fe angle of 180°. The refinement in the triclinic space group P1 leads to a slightly bent arrangement of the Fe–O–Fe fragment.     

Study on the formation and role of copper chloride hydroxide in the oxidative carbonylation of methanol to dimethyl carbonate

The synthesis of dimethyl carbonate by oxidative carbonylation of methanol over CuCl/SiO₂-TiO₂ catalysts has been investigated in a slurry reaction system. The γ-Cu₂(OH)₃Cl crystals were detected by X-ray diffraction on the catalysts after reaction. It was revealed that γ-Cu₂(OH)₃Cl was formed by CuCl reacting with O₂ and by-product water. The catalytic tests showed that γ-Cu₂(OH)₃Cl was largely inactive for this reaction, may be attributed to its high stability that resisted the Cu⁺/Cu²⁺ redox cycle.     

Reaction Mechanism of the Exchange Reaction between CuCl and BaO Studied by Time-Resolved X-ray Absorption Spectroscopy

The solid state reaction 2CuCl+BaO→Cu₂O+BaCl₂ has been examined in situ using energy-dispersive X-ray absorption fine-structure spectroscopy (DXAFS). A high time resolution on the order of seconds between two Cu K-XANES spectra has been achieved by this experimental setup. The spectra suggest that the transformation of CuCl to Cu₂O is preceded by an unidentified, intermediate state. Fingerprint methods as well as principal component analysis have been applied, which confirm the formation of exactly one new intermediate phase. The nature of this phase remains unidentified and could not be elucidated by the experimental investigations.     

Physico-chemical Properties of the Molten CuCl–CuCl<Subscript>2</Subscript> System: Experiment,Thermodynamics and Molecular Dynamics Simulations

The molten CuCl–CuCl₂ system was studied by means of the maximum bubble pressure method, thermodynamics and molecular dynamics simulations at temperatures of 835, 866, 905 and 943 K. The equilibrium constant of CuCl₂ decomposition has been determined with thermodynamic simulation. The density and molar volume of the CuCl–CuCl₂ system were established as a function of composition. Some evidence of ideality of CuCl–CuCl₂ solutions was observed. The molar volumes of pure liquid CuCl₂ are equal to 44.64, 46.23, 46.55 and 46.81 cm³·mol^?1 at 835, 866, 905 and 943 K, correspondingly. Radial distribution functions, coordination numbers, self-diffusion coefficients and trajectories of motion were obtained by molecular dynamics simulation. For this reason a new pair potential for Cu²⁺–Cl^? pair has been designed. The coordination number of Cu²⁺ by Cl^? is about 4. This value corresponds to literature data with regards to this coordination. The self-diffusion coefficients are close to diffusion coefficients measured in molten salts solutions.     

Synthesis and Structures of Dinuclear Copper(I) and Silver(I) 1, 3‐Bis[(2‐chloro)benzene]triazenide Complexes

In the presence of Et₃N, the reaction of 1, 3‐bis[(2‐chloro)benzene]triazene (HL) with CuCl or AgNO₃ gives the triazenide complexes {Cu₂(L)₂} ( 1 ) and {Ag₂(L)₂} ( 2 ), respectively. The X‐ray crystal structures of both complexes were obtained. The metal–metal distances (Cu ··· Cu and Ag ··· Ag) are 2.4974(5) and 2.7208(5) Å, respectively.     

A Study of Сu(II) Complexes with Pyruvic Acid Nicotinoyl and Isonicotinoyl Hydrazones by EPR and X-ray Absorption Spectroscopy

The composition and structure of the Cu²⁺ coordination cores in the previously synthesized [CuCl(HNPv)] · H₂O, [CuCl(HIPv)] · H₂O, [Cu(AOc)(HNPv)], [Cu(AOc)(HIPv)], [Cu(NO₃)(HNPv)], and [Cu(NO₃)(HIPv)] complexes, where HNPv and HIPv pyruvic acid nicotinoyl and isonicotinoyl hydrazones, respectively, have been determined. The binuclear complex [Cu₂(HNPv)₂(H₂O)2(μ-Cl)] has been synthesized for the first time and characterized by elemental analysis and IR, EPR, and EXAFS spectroscopy. Its dimeric structure has been proved by magnetic susceptibility measurement and EPR.     

CuCl2和HY分子筛的表面反应及Cu/Y分子筛的制备及其催化甲醇氧化羰基化

以CuCl₂为前驱物与HY分子筛进行固相离子交换制备了Cu/Y催化剂,采用热重方法研究了CuCl₂与HY分子筛的表面固相离子交换反应,结合活性测试表明催化剂中高度分散的CuCl和离子交换形式的Cu⁺物种是甲醇氧化羰基化合成碳酸二甲酯的催化活性中心。X射线光电子能谱表征和元素分析结果表明,活性金属Cu主要以CuCl形式存在于分子筛外表面,而在分子筛笼内则以交换的Cu⁺和少量吸附的CuCl形式存在。与以CuCl为交换铜源所制催化剂相比,以CuCl₂为铜源制备的催化剂Cu含量低,催化活性更高。     

Selective catalytic reduction of nitrogen monoxide with propene over CuCl/MCM-41 catalysts

Selective catalytic reduction of nitrogen monoxide with propene over two kinds of CuCl/MCM-41 catalysts prepared by a dispersion method has been studied. It was found that CuCl/AlMCM-41 exhibits substantially higher activity over CuCl/SiMCM-41. Characterization of these samples by H₂-TPR, IR and XRD showed that the active copper species were mainly related to Cu²⁺ and Cu⁺ ions in CuCl/AlMCM-41 catalyst.     

Synthesis, crystal structures and thermal properties of new copper(I)halide 2-ethylpyrazine coordination polymers: the influence of solid-state kinetics on product formation

Three new copper(I) coordination polymers were prepared by the reaction of copper(I) chloride with 2-ethylpyrazine in water at room temperature or under solvothermal conditions. In poly[CuCl(μ₂-2-ethylpyrazine-N,N′)] (I), “zig-zag”-like CuCl chains are present, which are connected by the 2-ethylpyrazine ligand to a three-dimensional network. In comparison in catena[Cu₃Cl₃(μ₂-2-ethylpyrazine-N,N′)₂] (II) six-membered Cu₃Cl₃ rings occur, which are connected to chains by the organic ligands. In poly[Cu₂Cl₂(μ₂-2-ethylpyrazine-N,N′)] (III), CuCl double chains are found, which are linked by the ligands to form sheets. The thermal behaviour of the different compounds was investigated using simultaneous thermogravimetry, differential thermoanalysis and mass spectroscopy as well as temperature-dependent X-ray powder diffraction. Two mass steps are found upon heating compound I in a thermobalance with 1°C/min, where the first corresponds to the transformation into compound III, and the second to the loss of the remaining ligands under formation of CuCl. If the heating rate is increased to 16°C/min, compound II is formed as an intermediate in a consecutive reaction. Therefore, the product formation depends on the actual heating rate, which shows that the solid-state kinetics plays an important role in such thermal reactions.     

A study by voltammetry and the photocurrent response method of copper electrode behavior in acidic and alkaline solutions containing chloride ions

The electrochemical behavior of Cu electrodes in Cl⁻ solutions was studied in a wide range of pH. The results were compared with those obtained in solutions containing F⁻, Br⁻, I⁻ and So²⁻₄ ions at pH 8.5, and discussed in terms of the competitive formation of Cu₂O and CuCl films on the Cu surface and the influence of CuCl on the properties of Cu₂O. At pH 8.5 or higher, Cu₂O was formed first, whereas at pH 5.7 or lower the Cu₂O film was formed on the Cu surface under the CuCl layer which was formed initially. It is believed that the Cu₂O films doped with Cl⁻ ions exhibited poor protective properties against Cu corrosion.     

Copper coordination complexes of bis(4-(pyridin-2-yl)pyrimidin-2-ylthio)methane with in situ metal redox reactions

Five copper coordination complexes 1–5 with 2-bppm (2-bppm?=?bis(4-(pyridin-2-yl)pyrimidin-2-ylthio)methane) have been prepared and structurally elucidated. Complexes 1 and 2 are both discrete dinuclear [2?+?2] macrocyclic structures, simultaneously formed in one-pot reaction with Cu(NO₃)₂ with in situ reduction of Cu²⁺. Similarly, dinuclear [2?+?2] macrocyclic motifs are found with 3 and 4, which are also obtained by one-pot reaction but with CuCl accompanied by in situ air oxidation of Cu⁺. Compound 5 exhibits a 1-D chain structure with 2-bppm and Cu₂I₂ connected one by one. Luminescence is measured for 2, 4, and 5, all based on d¹⁰-closed shell Cu(I).     

Recyclable CuMgAl hydrotalcite for oxidative esterification of aldehydes with alkylbenzenes

A series of hydrotalcite-like compounds with various Cu:Mg:Al molar ratios were prepared by the co-precipitation method. The catalytic performance for oxidative esterification of aldehydes was investigated. X-ray diffraction, N₂ adsorption–desorption (BET), hydrogen temperature-programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy, the scanning electron microscope (SEM), the transmission electron microscope and atomic absorption spectrometry were used to characterize the catalysts. The results showed that the benzyl benzoate product was obtained in good to excellent yield using tert-butyl peroxybenzoate as oxidant at 90°C under air atmosphere over Cu₂Mg₁Al₁-LDH catalyst. The catalyst can be recovered and used with 45% conversion after recycling five times. The oxidative esterification reaction in the heterogeneous system is environmentally friendly.

The Cu₂Mg₁Al₁-LDH catalyst prepared by co-precipitation method showed high catalytic activity for oxidative esterification of aldehydes. 81.0% yield of benzyl benzoate with benzaldehyde and toluene as reactants was obtained using tert-butyl peroxybenzoate as oxidant at 90°C under air atmosphere over Cu₂Mg₁Al₁-LDH catalyst. The catalyst can be recovered and used with 45% conversion after recycling five runs. The oxidative esterification reaction in the heterogeneous system is environmentally friendly.     

Isokinetic relationships at the thermal decomposition of tetranuclear copper(II)-complexes

A dependence of the activation energy upon the extent of conversion has been discovered for the thermal decomposition of Cu₄OCl₆L₄ with piperidine (1), morpholine (2), and triphenylphosphine oxide (3) as the ligand (L). Within the interval of conversions 0–0.3 the process shows a decrease in the activation energy (230–130 (1), 130–50 (2), and 200–100 (3) kJ mol^?1). The processes considered show an isokinetic relationship with T_iso = 255 ± 15 K which corresponds to a vibrational frequency of v_iso = 177 ± 10 cm^?1. This value accords well with IR absorption bands assigned to the stretching vibration in the trigonal CuCl₃ chromophore as predicted by theory. Based on this, an assumption about the CuCl₃-group as a central site of the reaction can be made. The IR- and X-ray data are presented to support the assumption made. © 1995 John Wiley & Sons, Inc.     

Semi-Continuous Heterophase Polymerization to Synthesize Nanocomposites of Poly(acrylic acid)-Functionalized Carbon Nanotubes

Two materials, pure poly(acrylic acid) (PAA) and nanocomposites with a matrix of PAA and carbon nanotubes (CNTs) as reinforcing agent were synthesized by semi-continuous heterophase polymerization (SHP). CNTs were prepared by a chemical vapor deposition technique and purified by steam. CNTs were characterized by a high resolution scanning electron microscopy (HRSEM) and Raman and Fourier transform infrared spectroscopies. Nanocomposites were prepared with: (i) purified CNTs (CNTs_p) or (ii) purified and functionalized CNTs possessing an acyl chloride moiety (CNTs_OCl). In both cases, the nanocomposites synthesis was carried out by in situ polymerization of acrylic acid (AA) by SHP. When CNTs_OCl were used previously to the polymerization of AA, a series of specific amounts of CNTs_OCl and AA were mixed to induce a chemical reaction between the carboxyl group of AA and the acyl chloride group of the CNTs_OCl. The product, acrylic acid grafted to CNTs_OCl (CNTs_OCl-AA), was used to prepare the PAA-CNTs_OCl nanocomposites. The PAA-CNTs_OCl nanocomposites were characterized by HRSEM, Raman, FTIR and CPMAS ¹³C-NMR spectroscopies and also by thermogravimetric analysis (TGA). The results reveal that PAA-CNTs_OCl nanocomposites were formed by PAA macromolecules grafted to CNTs_OCl. The kinetic behavior observed for the synthesis of pure PAA or PAA-CNTs_OCl nanocomposites by SHP was similar. Latexes of PAA-CNTs_OCl nanocomposites were stable without formation of a precipitate of CNTs_OCl for over 1.5 years, while latex prepared with CNTs_p and PAA, was unstable and formation of a precipitate of CNTs_p was observed immediately after its preparation. PAA-CNTs_p nanocomposites were characterized only by TGA. Moreover, latex of the PAA-CNTs_p nanocomposite that did not precipitate immediately after its preparation, turned into a gel; this gelation never occurred with the PAA-CNTs_OCl nanocomposite latex.     

Zur Reaktion der Alkin‐Kupfer(I)‐Komplexe [CuCl(S‐Alkin)] und [Cu2Br2(S‐Alkin)(dms)] (S‐Alkin = 3,3,6,6‐Tetramethyl‐1‐thia‐4‐cycloheptin,dms = Dimethylsulfid) mit den Lithiumorganylen Phenyllithium und Fluorenyllithium

Organometallic Compounds of Copper. XX On the Reaction of the Alkyne Copper(I) Complexes [CuCl(S‐Alkyne)] and [Cu₂Br₂(S‐Alkyne)(dms)] (S‐Alkyne = 3,3,6,6‐Tetramethyl‐1‐thiacyclohept‐4‐yne; dms = Dimethylsulfide) with the Lithiumorganyls Phenyllithium und Fluorenyllithium The alkyne copper(I) bromide complex [Cu₂Br₂(S‐Alkyne)(dms)] ( 3 b ) (S‐Alkyne = 3,3,6,6‐tetramethyl‐1‐thiacyclohept‐4‐yne; dms = dimethylsulfide) reacts with phenyllithium to form a tetranuclear copper(I) complex of the composition [Cu₄(C₆H₅)₂(S‐Alkenyl)₂] ( 7 ) in low yield (4%). The reaction of the alkyne copper(I) chloride complex [CuCl(S‐Alkyne)] ( 2 a ) with fluorenyllithium in tetrahydrofuran (thf) affords a lithium cuprate of the composition [Li(thf)₄]⁺ [Cu₂(fluorenyl)₃(S‐Alkyne)₂]^– ( 8 ) (yield 32%). The structures of both new complexes 7 and 8 were determined by X–ray diffraction.     

Crystal structure and magnetic properties of the novel mixed-valence copper coordination polymer constructed from two kinds of inorganic units

A novel mixed-valence Cu^I/Cu^II coordination polymer [Cu^I(μ₂-Cl)Cu^II(μ₃-S)(Phen)] _n (I) (Phen = 1,10-phenanthroline) has been hydrothermally synthesized and structurally characterized by elemental analyses and single-crystal X-ray diffraction. Single-crystal X-ray diffraction analysis reveals that a unique one-dimensional infinite chain-like structure is constructed by two unusual zigzag chains of [CuCl] _n and [CuS] _n . Both of the zigzag chains are used as the second building units (SBU) to produce a 2D helix-like layer at the aid of the C-H...Cl hydrogen bonding interactions between Phen groups and [CuCl] _n chains. An interesting three-dimensional network is formed with the supramolecular van der Waals contacting among the 2D layers. Finally, the magnetic properties of the title compound have been investigated in the temperature range 2–300 K.     

Synthesis,Characterization and Crystal Structures of new 1,2,4‐Triazole based Schiff‐bases and their Copper(I) Complexes

The reaction of 4‐amino‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)‐thione (AMTT, 1 ) with 4‐methoxy benzaldehyde and 3‐methoxybenzaldehyde in methanol led to the iminic derivatives 4‐(4‐methoxybenzylideneamino)‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)thione ( 2 , L1) and 4‐(3‐methoxybenzylideneamino)‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)‐thione ( 3 , L2). The reaction of the latter with [(PPh₃)₂CuCl] in methanol solution gave the first Cu^I complex of 3 , [(PPh₃)₂CuCl(L2)] ( 4 ) and in chloroform solution the complex [(PPh₃)₂CuCl(L2)]·2CHCl₃ ( 5 ). All compounds were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for 2 at ?80 °C: space group P2₁/c with a = 1351.3(3), b = 399.4(1), c = 2225.2(5) pm, β = 96.50(2)°, Z = 4, R₁ = 0.0667, for 3 at ?80 °C: space group R3c with a = b = 3020.4(2), c = 708.2(1) pm, Z = 18, R₁ = 0.0435, for 4 at ?80 °C: space group P2₁/c with a = 1427.8(1), b = 1129.0(1), c = 2622.8(2) pm, β = 97.19(1)°, Z = 4, R₁ = 0.0517 and for 5 at ?80 °C: space group with a = 1280.5(1), b = 1316.1(1), c = 1731.4(1) pm, α = 78.14(1)°, β = 86.06(1)°, γ = 64.69(1)°, Z = 2, R₁ = 0.0525.     

Two‐Dimensional Monovalent Copper Halide Coordination Polymers Incorporating Anti‐Conformation 3,3′‐Bipyridine

Hydrothermal treatment of aqueous mixtures of copper(II) halides and 3,3′‐bipyridine (3,3′‐bpy) has afforded the coordination polymers [CuCl(3,3′‐bpy)]_n ( 1 ) and [Cu₂Br₂(3,3′‐bpy)]_n ( 2 ), which were analyzed via single crystal X‐ray diffraction, infrared spectroscopy, and elemental analysis. The structure of 1 consists of two‐dimensional (2‐D) layers constructed from the linkage of castellated one‐dimensional (1‐D) [CuCl]_n stepped chains through anti‐conformation 3,3′‐bpy tethers. Compound 2 presents a related 2‐D sheet motif, albeit built from infinite 1‐D [Cu₂Br₂]_n ladders strutted by 3,3′‐bpy ligands in anti conformation. In both cases neighboring 2‐D sheets stack into 3‐D via weak C–H···halogen interactions.     

Solid-state reactions in the system Cu—Sb—O; Formation of a new copper(I) antimony oxide

The solid-state reactions in the system Cu—Sb—O were investigated by thermogravimetry and X-ray diffraction. Equimolar mixtures of CuO and Sb₂O₃ form Cu(II)Sb₂O₆ when slowly heated in air up to 1000°C. The firt step in this reaction is the oxidation of Sb₂O₃ to Sb₂O₄ at 380–500°C, followed by further oxidation of Sb₂O₄ and the formation of CuSb₂O₆ at 500–1000°C. Thermal decomposition of CuSb₂O₆ in a flowing nitrogen atmosphere occurs in three stages; the first, with an activation energy of 356 kJ mole^?1, results in the formation of a new copper(I) antimony oxide, with a composition of Cu₄SbO_4.5, as determined by atomic absorption analysis and X-ray fluoresecence. Confirmation of predominantly monovalent copper and pentavalent antimony in the new compound was by ESR and ESCA, respectively. Two forms of Cu₄SbO_4.5 have been distinguished; one of these (form II) has a structure of lower symmetry, and decomposes when heated in air at 600°C to a mixture of CuO and another new copper antimony oxide, as yet uncharacterized. On further heating to 1100°C in air, Cu₄SbO_4.5 (form I) gradually reforms. Details of these reactions are summarized and X-ray powder data presented for Cu₄SbO_4.5.     

Ionenaustauschexperimente an ternären Tantalaten und Niobaten mittels Halogenidschmelzen — ein Zugang zu neuen Bleitantalaten

Exchange Reactions of Ternary Tantalates and Niobates with Halide Melts — a Way to New Lead Tantalates Ternary tantalates and niobates of the hexagonal structure-type A_(n+1)/m^m+M_3n+1O_8n+3 (A^m+ = Na⁺, Cu⁺, Ag⁺,…; M = Ta, Nb) were heated with surplus CuCl, PbCl₂, LaCl₃ or BiCl₃ (for example T = 700°C in case of PbCl₂). In some of these cases it was possible to exchange the A^m+-ions for the cations of the halide melts by maintaining the basic structure (for example: Cu₃Ta₇O₁₉ + BiCl₃ = BiTa₇O₁₉ + 3 CuCl). In different reactions the stack along the crystallographic c-axis and furthermore the proportion O/M (for example: 7 Cu₅Ta₁₁O₃₀ + 35/2 PbCl₂ = 11 Pb_1,5Ta₇O₁₉ + PbO + 35 CuCl) changed. Nevertheless, it was not possible to substitute cations of the halide melt for A^m+-ions in every direction (not possible for example: LaTa₇O₁₉ + BiCl₃). When CuCl? and PbCl₂-melt were added to Ag₂Ta₄O₁₁ and Na₂Nb₄O₁₁, these niobates showed exange reactions by changing their structure completely. If BiCl₃-melt was added, these niobates decayed while forming B? Nb₂O₅. The new hexagonal tantalates Pb_1,5Ta₇O₁₉ (a = 6,2411(7) Å; c = 19,977(3) Å) and PbTa₄O₁₁ (low-temperature modification; a = 6,2364(3) Å; c = 36,851(3) Å) were the first representatives of the structure-type A_(n+1)/m^m+M_3n+1O_8n+3 with A^m+ = Pb²⁺, which were found in a reaction with PbCl₂ (Cu₃Ta₇O₁₉ + 3/2 PbCl₂ = Pb_1,5Ta₇O₁₉ + 3 CuCl; Ag₂Ta₄O₁₁ + PbCl₂ = PbTa₄O₁₁ + 2 AgCl). These two compounds, which are probably metastable, could only be achieved by exange reactions of ions.