Beiträge zum thermischen Verhalten von Sulfaten. VI. Zum chemischen Transport von CuSO4, Cu2OSO4 und CuO

Contributions on the Thermal Behaviour of Sulfates. VI. On the Chemical Transport of CuSO₄, Cu₂OSO₄, and CuO A powder of anhydrous CuSO₄ can be prepared by heating CuSO₄ · 5 H₂O in air or in an argon atmosphere. In the same way it is possible to get a powder of Cu₂OSO₄. But up to now, it was difficult to get crystals of CuSO₄ and there was no method known to synthesize crystals of Cu₂OSO₄. Investigations concerning chemical transport reactions of anhydrous heavy metal sulfates showed, that it is possible to get well formed crystals of CuSO₄ and Cu₂OSO₄ by deposition from a vapour phase. As transport agents for CuSO₄, Cl₂ and HgCl₂ are especially suitable. Less appropriate are HCl, NH₄Cl, and I₂. The chemical vapor deposition of Cu₂OSO₄ proceeds well with HgCl₂. In course of these investigations we recognized, that for CuO in addition to the well approved transport agents also Cl₂, HgCl₂ or I₂ (NH₄Cl less suitable) can successfully be used.     

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.     

Chemischer Transport von Mischkristallen im System CuMoO4/ZnMoO4

Chemical Vapour Transport of Solid Solutions in the CuMoO₄/ZnMoO₄ System Two solid solutions exist in the system CuMoO₄/ZnMoO₄: Cu_1‐xZn_xMoO₄ with x=0 to x=0.15 and x=0.20 bis x=1, respectively. Single crystals of Cu_1‐xZn_xMoO₄ were obtained by chemical vapor transport in the temperature gradient 973K→873K using Cl₂, Br₂ or NH₄Cl as transport agents. No difference of the Cu/Zn ratio between source and sink was observed for the transport agents Cl₂ and NH₄Cl. A slight shift to higher Zn amounts was observed for single crystals of Cu_1‐xZn_xMoO₄ grown using Br₂ as transport agent. The experimental results were compared with results of model calculations.     

Poly[μ2‐chloro‐μ2‐1,4‐oxathiane‐κ2S:S‐copper(I)]

The title complex, [CuCl(C₄H₈OS)]_n, contains infinite spiral (CuS)_n chains linked by bridging Cl atoms into layers. The Cl atoms do not form polymeric fragments with Cu^I, but combine into isolated centrosymmetric Cu₂Cl₂ units. The compound is non‐isomorphous with the Br‐containing analogue, which contains Cu₈S₈ rings linked by Br atoms into chains. The O atom of the 1,4‐oxathiane mol­ecule does not realize its coordination abilities in the known copper(I)–halide complexes, while in copper(II)–halide complexes, oxathiane is coordinated via the S and O atoms. This falls into a pattern of the preferred inter­actions, viz. weak acid (Cu^I atom) with weak base (S atom) and harder acid (Cu^II atom) with harder base (O atom).     

Structural and Spectroscopic Studies of Halocuprate(I) and Haloargentate(I) Complexes [M2XnX′4−n]2−

The complexes [Cu₂Br₄]^2?, [Cu₂I₄]^2?, [Cu₂I₂Br₂]^2?, [Cu₂I₃Cl]^2?, [Ag₂Cl₄]^2? have been characterized as their isomorphous bis(triphenylphosphoranylidene)ammonium ([Ph₃PNPPh₃]⁺ = PNP⁺) salts by single crystal structural determinations. All anions show the centrosymmetric doubly halogen‐bridged forms [XM(μ‐X)₂MX]^2? with three‐coordinate metal atoms that have been observed in [M₂X₄]^2? complexes with other large organic cations. In [Cu₂I₂Br₂]^2? the iodide ligands occupy the bridging positions and the bromide the terminal positions, while in [Cu₂I₃Cl]^2?, obtained in an attempt to prepare [Cu₂I₂Cl₂]^2?, two of the iodide ligands occupy the bridging positions with the third iodide and the chloride ligand occupying two statistically disordered terminal positions. In [Ag₂Cl₄]^2? the distortion from ideal trigonal coordination of the metal atom is greater than in the copper complexes, but less than in other previously reported [Ag₂Cl₄]^2? complexes with organic cations. The ν(MX) bands have been assigned in the far‐IR spectra, and confirm previous observations regarding the unexpectedly simple IR spectra of [Cu₂X₄]^2? complexes.     

ϵ‐RbCuCl3, a new polymorph of rubidium copper trichloride: synthesis,structure and structural complexity

A novel polymorph of RbCuCl₃ (rubidium copper trichloride), denoted ϵ‐RbCuCl₃, has been prepared by chemical vapour transport (CVT) from a mixture of CuO, CuCl₂, SeO₂ and RbCl. The new polymorph crystallizes in the orthorhombic space group C222₁. The crystal structure is based on an octahedral framework of the 4H perovskite type. The Rb⁺ and Cl⁻ ions form a four‐layer closest‐packing array with an ABCB sequence. The Cu²⁺ cations reside in octahedral cavities with a typical [4 + 2]‐Jahn–Teller‐distorted coordination, forming four short and two long Cu—Cl bonds. ϵ‐RbCuCl₃ is the most structurally complex and most dense among all currently known RbCuCl₃ polymorphs, which allows us to suggest that it is a high‐pressure phase, which is unstable under ambient conditions.     

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.     

Beiträge zum thermischen Verhalten von Oxoniobaten der Übergangsmetalle. IV. Zum Chemischen Transport von CoNb2O6 mit Cl2, NH4 und HgCl2. Experimente und Modellrechnungen

Contributions on the Thermal Behaviour of Oxoniobates of the Transition Metals. IV The Chemical Vapour Transport of CoNb₂O₆ with Cl₂, NH₄Cl, or HgCl₂. Experiments and Calculations Well shaped crystals of CoNb₂O₆ were obtained by CVT using Cl₂ (added as PtCl₂), NH₄Cl or HgCl₂ as transport agents (1020°C → 960°C). As a result of thermodynamic calculations the evaporation and deposition of CoNb₂O₆ in the presence of Cl₂ can be expressed by the heterogenous endothermic equilibrium (1). The endothermic reaction (2) is responsible for the CVT of CoNb₂O₆ if NH₄Cl is used as transport agent: The unfavourable site of the equilibrium (3) causes the small transport effect using HgCl₂ as transport agent. Assuming Δ_BH°₂₉₈(CoNb₂O_6,s) = ?524.7 kcal/mol a satisfying agreement between thermodynamical calculation and experimental results can be reached.     

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。     

Beiträge zum thermischen Verhalten von Sulfaten. VII [1, 2]. Zum chemischen Transport von ZnSO4 und Zn3O(SO4)2

Contributions on the Thermal Behaviour of Sulfates. VII. On the Chemical Transport of ZnSO₄ and Zn₃O (SO₄)₂ A powder of anhydrous ZnSO₄ can be prepared by heating ZnSO₄ · 7H₂O in air or in an argon atmosphere. In the same way it is possible to get a powder of Zn₃O(SO₄)₂. But up to now, it was difficult to get crystals of ZnSO₄ and there was no method known to synthesize crystals of Zn₃O(SO₄)₂. Investigations concerning chemical transport reactions of anhydrous heavy metal sulfates showed, that it is possible to get well formed crystals of ZnSO₄ and Zn₃O(SO₄)₂ by deposition from a vapour phase. Cl₂, HgCl₂, HCl, NH₄Cl and PbCl₂ were tested as transport agents and found suitable. If halides are used as transport agents, it is significant, that SO₃ can oxidize them to the halogens which are then the true transport agents. By use of PbCl₂ as a very effective transport agent, PbSC₄ will appear as an additional condensed phase. Thermodynamical considerations made it possible to understand the transport processes in these systems and to choose suitable conditions for our experiments.     

Aqua(2,2′‐bi‐1H‐imidazole)chloro­copper(II) chloro­(imino­diacetato)copper(II) monohydrate

In the title compound, [CuCl(C₆H₆N₄)(H₂O)][Cu(C₄H₅NO₄)Cl]·H₂O, the Cu^II atom in the cation is coordinated by one Cl⁻ ion, two N atoms of the 2,2′‐biimidazole ligand and one aqua ligand. Within the anion, the Cu^II atom is bonded to one Cl⁻ ion, and one N and two O atoms of the imino­diacetate ligand. Neighbouring cations and anions are connected to each other by Cu·Cl semi‐coordination bonds of 2.830 (12) and 3.071 (12) Å, forming a Cu₂Cl₂ rectangular unit. The dinuclear units further link into a polymeric chain along the a axis through Cu·O_aqua interactions of 2.725 (3) Å. Including the long coordination bonds, the geometries around the Cu atoms in the cation and anion are square‐pyramidal and distorted octahedral, respectively.     

Oxocentered Units in Three Novel Rb‐Containing Copper Compounds Prepared by CVT Reaction Method

Three novel copper compounds, Rb₄Cu₄OCl₁₀ ( I ), Rb[Cu₃O](SeO₃)₂Cl ( II ), and RbCu₃(OH)(SeO₃)Cl₄(H₂O)₃ ( III ) were prepared by chemical vapor transport (CVT) reactions method from mixtures of CuO, SeO₂, RbCl, and CuCl₂. The crystal structures of the three compounds were determined by direct methods. Compound I is a Rb analogue of ponomarevite, K₄Cu₄OCl₁₀. Its crystal structure contains {[OCu₄]Cl₁₀}^4– clusters with oxocentered [OCu₄]⁶⁺ tetrahedra as cores. The clusters are linked by the Rb⁺ cations. The crystal structure of II contains complex {[O₂Cu₆](SeO₃)₄Cl₂}^2– layers formed by dimers of edge‐sharing [OCu₄]⁶⁺ tetrahedra interlinked via selenite groups and Cl^– anions. The crystal structure of III is based upon {[(OH)Cu₃](SeO₃)}³⁺ layers formed by the [(OH)Cu₃]⁵⁺ tetrahedra attached to (SeO₃)^2– groups. The layers are linked via Cl^– anions and via hydrogen bonds to H₂O molecules.     

Der chemische Transport von Cu,Ag, Au,Ru, Rh,Pd, Os,Ir, Pt unter Mitwirkung von Gaskomplexen. Al2Cl6, Fe2Cl6 oder Al2J6 als Komplexbildner

The Chemical Transport of Cu, Ag, Au, Ru, Rh, Pd, Os, Ir, Pt in the Presence of Al₂Cl₆, Fe₂Cl₆ or Al₂I₆, Causing Complex Formation Chemical transport experiments show, that the title elements (with exception of Os) in the presence of halide forming agents (HCl, Cl₂ or I₂ resp.) and of complex forming agents (Al₂Cl₆, Fe₂Cl₆ or Al₂I₆ resp.) give gaseous complex compounds with a remarkable stability. This leads to novel possibilities for the chemical transport of the elements and their compounds. The effect of complex formation can be predicted on the basis of qualitative thermodynamic considerations. The corrosion of the wall of the quartz ampoule at temperatures above 600°C by Al₂Cl₆/AlCl₃ is avoidable by the usage of Fe₂Cl₆/FeCl₃ instead of Al₂Cl₆/AlCl₃. Experiments in the system Pd/I₂, Al₂I₆ lead to the formation of crystals of Pd₂Al.     

Amination and amidation of aryl iodides catalyzed by copper(I)-phenanthroline complexes

Four kinds of copper(I)-phenanthroline complexes ([Cu^I(phen)₂]Cl, [Cu^I(phen)Cl]₂, [Cu^I(phen)₂]BF₄, and Cu^I(phen)PPh₃Cl) were prepared and used as catalysts for amination and amidation of aryl iodide to investigate the influence on the yields of products due to differences of the structures. These complexes were found to work as catalysts on these reactions and showed that the differences of structures of copper(I) complexes significantly influenced the yield of aryl-nitrogen bond forming processes.     

Poly[di‐μ3‐chloro‐μ2‐trans‐1,2‐di‐4‐pyridylethyl­ene‐dicopper(I)]: a two‐dimensional organic–inorganic hybrid constructed from linear CuCl clusters and bridging ligands

The structure of the title compound, [Cu₂Cl₂(C₁₂H₁₀N₂)]_n, contains infinite CuCl staircase‐like chains, which lie about inversion centres. The trans‐1,2‐di‐4‐pyrid­ylethyl­ene mol­ecules also lie about inversion centres and connect the CuCl chains through Cu—N coordination bonds into a two‐dimensional organic–inorganic hybrid network. The planar sheets are stacked along the c axis and associated through weak C—H⋯Cl inter­actions. The results show a reliable structural motif with controllable separation of the CuCl chains by variation of the length of the ligand.     

Crystal structure determination of complexes of monomethylammonium chloride and mercury(II) chloride: CH3NH3HgCl3, (CH3NH3)2HgCl4, and CH3NH3Hg2Cl5

The crystal structures have been determined of CH₃NH₃HgCl₃, (CH₃NH₃)₂HgCl₄, and CH₃NH₃Hg₂Cl₅. In (CH₃NH₃)₂HgCl₄ the Hg^II atom is tetrahedrally coordinated by four Cl atoms with Hg? Cl bond lengths of 2.464 to 2.478 Å. In the other two compounds the Hg^II atom is involved in two short covalent Hg? Cl bonds, forming a pseudo HgCl₂ molecule and two much longer bridging Hg? Cl bonds. The methylammonium groups are connected by hydrogen bonds to the chlorine atoms. The nature of the hydrogen bonding scheme probably causes disorder of the methylammonium groups.     

Gaseous Chloride Complexes with Halogen Bridges—Homo-Complexes and Hetero-Complexes

The chemistry of the gaseous halide complexes which have been observed in large numbers in recent years is discussed for the example of chlorides. Homo-complexes—dimeric or polymeric chloride molecules containing chlorine-bridge linkages [e.g.(NaCl)_n, n = 2—4; (CuCl)_n, n = 2—5; (BeCl₂)_n, n = 2—4; Pd₆Cl₁₂]—occur through broad areas of the Periodic Table. Comparison of the dissociation enthalpy of such molecules with the vaporization enthalpy of the liquid chlorides is particularly informative. Hetero-complexes are formed from different chloride molecules by linkage through Cl bridges. Not only 1:1 complexes (e.g. NaAlCl₄, TIPbCl₃, KThCl₅, CdPbCl₄, AlUCl₈) but also larger molecules (e.g. CoAl₂Cl₈, CrAl₃Cl₁₂, Cu₂UCl₆, In₂UCl₁₀) are known. Types of formulas, structures, and above all the formation enthalpies of such complexes are discussed critically. Hetero-complexes are useful in chemical transport reactions, as aids in syntheses, and in gas-chromatographic separations (lanthanoids, actinoids). They also play a part in many industrial processes (chlorination of ores) and in recently developed types of high-pressure discharge tubes.     

Crystal structure of the copper(II) chloride complex with 3,5Dimethyil-4-Amino-l,2,4-Triazole and water

The crystal structure of the copper(II) chloride complex with 3,5-dimethyl-4-amino-1,2,4-triazole has been determined by XRD. The crystal is cubic, a = 17.754(4) å, V_cell = 5596(1) å³, space group Pa3, Z = 8, d_calc = 1.842 g/cm³, C₁₂H₂₈Cl₆Cu₃N¹²O₂, Syntex P2₁, λCuK_a, 3277 I_hkl measured, including 936 independent nonextinct I_hkl > 0 (R_int = 0.0557), an absorption correction applied using crystal habit data (Μ = 82.4 cm¹), R(F) = 0.0711, R(wF²) = 0.1899 for 831 F^hkl > 4Σ(F). The copper atoms are linked by three bridging bidentate ligands into a regular triangle; the ligands are coordinated by the N¹ and N² atoms of the triazole cycle and by the Μ₃-bridging oxygen atom. The coordination polyhedron of copper is a heavily distorted octahedron (2N, O, Cl) + Cl+O. The chemical formula of the compound is discussed. An unambiguous choice between the formulas (H₃O)[(Μ₃-OH)(Μ,η²-L)₃Cu₃Cl₆] and [(Μ₃-OH)(Μ,η²-L)₂(Μ₂, η²-LH)Cu₃Cl₆]·H₂O is impossible, since the hydrogen atoms were not localized experimentally.     

Die relative Unterkühlung an Quarzglasoberflächen und anderen Substraten beim chemischen Transport fester Stoffe über die Gasphase

The Relative Undercooling on Silica Glass Surfaces and other Substrates during the Chemical Transport of Solids via the Vapor-phase . The relative undercooling on etched surfaces of silica glass at the chemical transport of ZnS in a stream of gaseous iodine at 652–854°C is found to be ΔT = 37–43°. Scrapers on silica glass lead to a substantial smaller undercooling. During the deposition of ZnS (made from “pure” components) in a temperature gradient one finds a remarkable fractionation. In closed (etched) silica glass ampoules the relative undercooling is determined for the systems ZnS/I₂, ZnSe/I₂, ZnS/HCl; ZnS/H₂, CdS/I₂, CdSe/I₂, Al₂S₃/I₂ and Nb₂O₅/NbCl₅ using a special furnace, The region free of nuclei (or crystals) for instance at T₂ ≈ 800°C depending on the system (and T₂) is ΔT ≈ 13–45°. The variation of the substrates showed: for fire polished silica surfaces for ZnS/I₂ is ΔT ≈ 56°; for the different quartz-faces and ZnS/I₂ is ΔT ≈ 13–35°. Generally, on different substrates (broken pieces, fragments) one finds for ZnS/I₂ ΔT ≈ 20–28°. Using another way for the systems MoO₃/Cl₂, MoO₃/Cl₂, Ar, MoO₃/Cl₂, O₂ and MoO₃/HgCl₂ with T₂ a strongly decreasing value of ΔT is found.     

Transformations in Chemically Responsive Copper‐Calixarene Architectures

Self‐assembly of bis‐picolyl‐appended calix[4]arene ( L ) with Cu^I or Cu^II salts resulted in a collection of multinuclear architectures capable of expressing structural reconfigurations in response to various chemical stimuli: addition of copper salt, solvents, or oxidation. Coordination of L to CuX (X=Br, I) selectively yielded dinuclear macrocycles Cu^I ₂ L₂Br₂ ( 1 ) and Cu^I ₂ L₂I₂ ( 3 ) that were transformed into tetranuclear assemblies Cu^I ₄ L₂Br₄ ( 2 ) and Cu^I ₄ L₂I₄ ( 4 ) upon further addition of CuX. These supramolecules persist as robust and discrete entities in solution that display red emission; notably, 4 exhibits luminescence thermochromism. Assembly of L with CuCl₂ produced macrocycle Cu^II ₂ L₂Cl₄ ( 5 ), which crystallised as cage [Cu^II ₂ L₄(μ‐Cl)]³⁺ ( 6 ) in the presence of MeOH. Two chemical signals—introduction of CuCl₂ and addition of CH₃CN—regenerated macrocycle 5 . Coordination of L to Cu(OTf) yielded macrocycle Cu^I ₂ L₂(OTf)₂ ( 7 ) that also crystallised as cage 6 upon oxidation in CHCl₃.