Synthesis,characterization and crystal structures of the bidentate Schiff base N,N′‐bis(2‐nitrocinnamaldehyde)ethylenediamine and its complex with CuNCS and triphenylphosphane

Reaction of copper(I) thiocyanate and triphenylphosphane with the bidentate Schiff base N,N′‐bis(trans‐2‐nitrocinnamaldehyde)ethylenediamine {Nca₂en, (1); systematic name (1E,1′E,2E,2′E)‐N,N′‐(ethane‐1,2‐diyl)bis[3‐(2‐nitrophenyl)prop‐2‐en‐1‐imine]}, C₂₀H₁₈N₄O₄, in a 1:1:1 molar ratio in acetonitrile resulted in the formation of the complex {(1E,1′E,2E,2′E)‐N,N′‐(ethane‐1,2‐diyl)bis[3‐(2‐nitrophenyl)prop‐2‐en‐1‐imine]‐κ²N,N′}(thiocyanato‐κN)(triphenylphosphane‐κP)copper(I)], [Cu(NCS)(C₂₀H₁₈N₄O₄)(C₁₈H₁₅P)] or [Cu(NCS)(Nca₂en)(PPh₃)], (2). The Schiff base and copper(I) complex have been characterized by elemental analyses, IR, electronic and ¹H NMR spectroscopy, and X‐ray crystallography [from synchrotron data for (1)]. The molecule of (1) lies on a crystallographic inversion centre, with a trans conformation for the ethylenediamine unit, and displays significant twists from coplanarity of its nitro group, aromatic ring, conjugated chain and especially ethylenediamine segments. It acts as a bidentate ligand coordinating via the imine N atoms to the Cu^I atom in complex (2), in which the ethylenediamine unit necessarily adopts a somewhat flattened gauche conformation, resulting in a rather bowed shape overall for the ligand. The NCS⁻ ligand is coordinated through its N atom. The geometry around the Cu^I atom is distorted tetrahedral, with a small N—Cu—N bite angle of 81.56 (12)° and an enlarged opposite angle of 117.29 (9)° for SCN—Cu—P. Comparisons are made with the analogous Schiff base having no nitro substituents and with metal complexes of both ligands.     

Electronic structures of YBa2Cu3OY doped by La

Based on the EHMO approach, the band structures for the Y? Ba? Cu? O superconductors doped by La were calculated. The influence of the partial substitutions of La for Y and Ba in YBa₂CU₃O_y on its electronic structures was investigated. The results demonstrate that the La doping at the Ba site has a great effect on the electronic structures of the Y? Ba? Cu? O superconductors, whereas the change in the band structures caused by the La doping at the Y site is very small. The increase in the oxygen content caused by the La doping results in an increase in the densities of states at E_f, N(E_f), for La_1+x Ba_2?xCu₃O_y, but the increase in N(E_f) cannot compensate the decrease caused by the La doping at the Ba site. In addition, the 2D Cu? O planes are much more sensitive to the change in N(E_f) than are the 1D Cu? O ribbons, which implies an important role of the 2D Cu? 0 planes in the Y? Ba? Cu? O superconducting system, regardless of whether La substitutes for Y or for Ba. © 1995 John Wiley & Sons, Inc.     

Influence of the degree of surface oxidation of polycrystalline Rh electrodes on the underpotential deposition of Cu

The underpotential deposition of copper onto polycrystalline rhodium was studied as a function of the degree of oxidation of the electrode surface in acidic media using potentiodynamic techniques. Surface oxidation of the rhodium electrode was carried out using a triangular sweep potential between E _L (lower limit) and E _U (upper limit: 0.94≤E _U≤1.4 V). Cu electrodeposition was performed at the same time as the total or partial reduction of the oxidized species. The surface oxides produced at E _U≤1.09 V were completely reduced during Cu electrodeposition. In this case, the potentiodynamic I-E patterns for oxidative dissolution of Cu were characterized by three anodic peaks located at 0.41 V (peak I), 0.47 V (peak II) and 0.59 V (peak III) and the coverage degree by Cu, θ_Cu, was on the order of a monolayer. Surface oxides produced at E _U>1.09 V were partially reduced during the copper electrodeposition. In this case, the I-E profiles exhibited only two anodic peaks (II and III) and θ_Cu was <1. The Rh-oxygen species that remain on the electrode surface block the active sites of lower energy and modify the binding energy of strongly adsorbed Cu. Electronic Publication     

A tetranuclear copper(II) complex: crystal structure,assembly, EPR,electrochemistry and magnetism

A tetranuclear copper(II) complex, [Cu₂L]₂(ClO₄)₂ · 4H₂O (1), where H₃L = N,N′-bis(4-(3′-formyl-5′-chlorosalicyclidene)iminoethyl)-4-chloro-2,6-bimethyliminophenol, has been synthesized and structurally characterized by ES-MS, IR and X-ray crystallography. The complex is a dimer of two dinuclear copper(II) acylic enantiomorph subunits ([Cu₂L]ClO₄ · 2H₂O), held together by π–π, coordination and hydrogen bond interactions. The Cu–Cu separation in each subunit, bridged by one phenoxide, is 3.228 Å, and the shortest distance of Cu–Cu between the two subunits is 3.252 Å. There are two crystallographically unique copper(II) environments, one (Cu1) is square-based pyramidal with O₃N₂ donor set, another (Cu2) square planar with O₂N₂ donor set. The cyclic voltammogram of the complex shows that it undergoes two stepwise reduction processes, E _pc = ?0.707 and ?0.850 V, respectively. Magnetic measurements in the 2–300 K range indicate strong antiferromagnetic interactions between Cu(II) ions in each subunit with the exchange constant J = ?211(2) cm^?1. The observation has been rationalized on the basis of the effective magnetic pathway.     

Two Diammonium Copper Azides with Similar Layerlike Magnetic Substructures Made of Chains of Serially Connected Cu6 Rings Show Cation‐Modulated Magnetism

We present here the first examples of Cu–azide compounds synthesized by using protonated diamine ions as cationic templates: (dmenH₂)[Cu₆(N₃)₁₄] and (trimenH₂)[Cu₆(N₃)₁₄] (dmenH₂²⁺: N,N′‐dimethylethylenediammonium; trimenH₂²⁺: N,N,N′‐trimethylethylenediammonium). Both compounds possess a similar, rarely observed anionic Cu–azide layer, which consists of [Cu₆(N₃)₁₄^2?]_n anionic chains linked by asymmetric end‐to‐end azido bridges. The chain, in turn, is made up of elongated Cu₆ rings, with double and single end‐on azido linkages between the square‐planar Cu²⁺ sites within the ring and double end‐on azido bridges serially connecting the rings. The molecular geometry results in ferromagnetic interactions within the Cu–azide layer in both compounds. The interlayer separations are determined by the cations, with the shortest interlayer Cu???Cu separations being 8.016 Å for the dmenH₂²⁺ compound and 9.106 Å for the trimenH₂²⁺ compound. These different interlayer separations tune the magnetic properties of the two materials. The dmenH₂²⁺ compound displays long‐range antiferromagnetic ordering at lowtemperature and short‐range ferromagnetic interaction at high temperature, while only short‐range ferromagnetism was observed in the trimenH₂²⁺compound at 2–300 K.     

A linear trinuclear complex of copper(II) with N,N′-bis(2-hydroxy-5-methoxybenzelidene)-1,3-diiminopropane

The synthesis and X-ray crystal structure of a linear phenolate-bridged Cu(II) complex 1 with a Cu–Cu bond distance of 2.9260(5)?Å is reported. The complex consists of three Cu(II) ions with two molecules of the N,N′-bis(2-hydroxy-5-methoxybenzelidene)-l,3-diiminopropane ligand and two nitrate ions in such a manner that one ligand is connected with two Cu(II) ions. The complex is monoclinic, space group P2₁/n, with a?=?10.6305(5), b?=?13.0719(7), c?=?14.6336(8)?Å and β?=?102.549(1)° at 293?K, Z?=?2. The structure shows deprotonation of the phenolate oxygen to form a μ₂ bridge. The magnetic moment (1.627 BM per Cu₃ unit) at 300?K reveals that the spin doublet state is the ground state.     

Effects of Temperature and Anion on the Copper(II) Complexes based on 2‐(Carboxyphenyl)iminodiacetic Acid and 1,10‐Phenanthroline

Using Cu(NO₃)₂ as metal salt, [Cu₃(cpida)(phen)₂(H₂O)₅] · 3NO₃ · 2H₂O ( 1 ) and {[Cu₂(cpida)(phen)(NO₃)] · 2H₂O}_n ( 2a ) were synthesized from an identical starting mixture with 2‐(carboxyphenyl)iminodiacetic acid (H₃cpida) and 1,10‐phenanthroline (phen) at 5 °C and 25 °C, respectively. Additionally, complexes 2b – 2d , which are isostructural to 2a , were obtained using Cu(ClO₄)₂, Cu(BF₄)₂, and Cu(CF₃SO₃)₂ instead of Cu(NO₃)₂ in the temperature range 0–65 °C. 1 is characterized by a V‐shaped trinuclear Cu^II monomer, whereas 2a – 2d features a one‐dimensional (1D) Δ Cu^II chain. Abundant hydrogen bonds constructed by the nitrate anion are observed in 1 . A structural transformation study was undertaken and revealed that 1 could completely transform into 2a from the reaction solution at 25 °C and the temperature plays a crucial role in the process. Magnetic measurements revealed that 1 exhibits dominant antiferromagnetic behavior, whereas 2a presents dominant ferromagnetic behavior.     

Synthesis and structure of amide oxygen-bridged polymeric and monomeric copper(II) complexes with aroylhydrazones

The synthesis and structure of two Cu(II) complexes, {[Cu₂(L¹)₂]?·?DMF} _n (1) and [CuL²(phen)] (2), are described. The dinegative hydrazones are obtained by deprotonation of both phenolic and amide moieties of N′-(5-bromo-2-hydroxybenzylidene)-3,5-dimethoxybenzohydrazide (H₂L¹) and N′-(2-hydroxybenzylidene)pyrazine-2-carbohydrazide (H₂L²). In each complex the planar ligand binds the metal ion via phenolate-O, imine-N, and amide-O. Complex 1 is a polymer in which phenoxo-bridged binuclear Cu(II) units are further joined by equatorial–apical amide-O bridges. The Cu···Cu separations are 3.0306 and 3.8217?Å for the phenolate-O bridged pair and the amide-O bridged pair, respectively. Complex 2 is a monomer where chelating phen displays axial–equatorial bonding, with square-pyramidal Cu(II).     

Direct Electron Transfer and Electrocatalysis of Myoglobin Based on its Direct Immobilization on Carbon Ionic Liquid Electrode

Direct electron transfer of myoglobin (Mb) was achieved by its direct immobilization on carbon ionic liquid electrode (CILE) with a conductive hydrophobic ionic liquid, 1‐butyl pyridinium hexaflourophosphate ([BuPy][PF₆]) as binder for the first time. A pair of well‐defined, quasi‐reversible redox peaks was observed for Mb/CILE resulting from Mb redox of heme Fe(III)/Fe(II) redox couple in 0.1 M phosphate buffer solution (pH 7.0) with oxidation potential of ?0.277 V, reduction potential of ?0.388 V, the formal potential E°′ (E°′=(E_pa+E_pc)/2) at ?0.332 V and the peak‐to‐peak potential separation of 0.111 V at 0.5 V/s. The average surface coverage of the electroactive Mb immobilized on the electrode surface was calculated as 1.06±0.03×10^?9 mol cm^?2. Mb retained its bioactivity on modified electrode and showed excellent electrocatalytic activity towards the reduction of H₂O₂. The cathodic peak current of Mb was linear to H₂O₂ concentration in the range from 6.0 μM to 160 μM with a detection limit of 2.0 μM (S/N=3). The apparent Michaelis–Menten constant (K and the electron transfer rate constant (k_s) were estimated to be 140±1 μM and 2.8±0.1 s^?1, respectively. The biosensor achieved the direct electrochemistry of Mb on CILE without the help of any supporting film or any electron mediator.     

Formation of nanoparticles of a new metastable copper compound in the copper acetate hydrate/poly(acrylonitrile) heterogeneous system

We use X-ray powder diffraction to study heterogeneous solid-phase reactions induced by IR radiation in the system Cu(OOCCH₃)₂·H₂O/PAN and intermediate copper compounds in the synthesis of copper nanoparticles. The composite Cu(OOCCH₃)₂ · H₂O/PAN after annealing contains crystallites of copper (l _Cu = 16 nm), a new metastable compound Cu _x>2O ( $ l_{Cu_{x > 2} O} We use X-ray powder diffraction to study heterogeneous solid-phase reactions induced by IR radiation in the system Cu(OOCCH₃)₂·H₂O/PAN and intermediate copper compounds in the synthesis of copper nanoparticles. The composite Cu(OOCCH₃)₂ · H₂O/PAN after annealing contains crystallites of copper (l _Cu = 16 nm), a new metastable compound Cu _x>2O ( = 20 nm), and Cu₂O ( = 20 nm). After 45 days of air exposure, the intensity of Cu _x>2O reflections in the composite decreases dramatically, whereas that of copper reflections increases. Cu _x>2O has a monoclinic unit cell with the parameters a = 5.424, b = 3.196, c = 3.072 ?, β = 119.51°. Original Russian Text ? V.M. Novotortsev, V.V. Kozlov, Yu.M. Korolev, G.P. Karpacheva, L.V. Kozhitov, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 7, pp. 1087–1089.     

Synthesis,Characterization, and Crystal Structures of [Cu(ca2en)2]ClO4, and [Cu(ca2en)(PPh3)2]ClO4 Complexes

Synthesis, spectroscopy, and crystal structures of [Cu(ca₂en)₂]ClO₄ ( 1 ) and [Cu(ca₂en)(PPh₃)₂]ClO₄ ( 2 ) (ca₂en=N,N′‐bis(trans‐cinnamaldehyde)ethylenediimine) are reported. Compound 1 crystallizes in the orthorhombic space group Pbca, with a=12.5647(7), b=21.8203(11), c=27.992(2) Å, V=7674.3(7) ų, Z=8. Compound 2 crystallizes in the triclinic space group P , with a=13.0540(11), b=14.2935(13), c=14.9863(13) Å, α=84.130(2), β=69.761(2), γ=87.749(2)°, V=2609.8(4) ų, Z=2. The coordination polyhedron about the Cu^I center in the two complexes is best described as a distorted tetrahedron. The ¹H‐NMR and electronic spectra of these complexes are also reported and discussed. The cyclic voltammetry of the complexes indicate a quasireversible redox behavior for complex 1 (E_1/2=0.51 V). However, complex 2 displays an irreversible oxidation wave at 0.91 V. A weak emission is observed for complex 2 in CHCl₃ at room temperature.     

Structural and NMR Studies of the Hexameric Copper(I) Complex with N‐n‐butyl‐N′‐ethoxycarbonyl‐thioureate

The copper sulfide mineral flotation collector, N‐n‐butyl‐N′‐ethoxycarbonyl‐thiourea (H₂bectu), and the 1:1 hexameric copper(I) thioureate complex, [Cu(Hbectu)]₆, have been characterized by single crystal X‐ray diffraction. H₂bectu crystallizes in the triclinic space group with a = 5.2754(4), b = 9.0042(7), c = 12.6030(9) Å, α = 80.528(6), β = 90.173(6), γ = 76.472(7)°. An intramolecular N‐H···O hydrogen bond between the thioamide proton and carbonyl oxygen forms a planar six‐membered ring in the central core of the molecule with C=O, C=S and C‐N bond lengths in accord with those reported for other N‐alkyl/aryl‐N′‐acyl‐thiourea compounds. [Cu(Hbectu)]₆ crystallizes in the monoclinic space group C2/c with a = 23.269(5), b = 13.243(4), c = 23.037(7) Å, β = 91.81(2)° as discrete hexameric clusters disposed about a crystallographic centre of symmetry with a Cu₆S₆ core consisting of two Cu₃S₃ chair‐shaped rings linked by coordination of the deprotonated amide nitrogen atom to a copper atom in the adjacent ring. The six ligands assemble as a paddlewheel structure with the ethoxy and n‐butyl substituents packing in an alternating head to tail arrangement. Temperature dependent solution ¹H NMR spectroscopic studies show that the hexameric structure of the complex is maintained in solution.     

Synthesis and crystal structure of the dinuclear copper(II) Schiff base complex μ‐hydroxido‐μ‐chlorido‐bis{[bis(trans‐2‐nitrocinnamaldehyde)ethylenediamine]chloridocopper(II)} dichloromethane sesquisolvate

Transition metal complexes of Schiff base ligands have been shown to have particular application in catalysis and magnetism. The chemistry of copper complexes is of interest owing to their importance in biological and industrial processes. The reaction of copper(I) chloride with the bidentate Schiff base N,N′‐bis(trans‐2‐nitrocinnamaldehyde)ethylenediamine {Nca₂en, systematic name: (1E,1′E,2E,2′E)‐N,N′‐(ethane‐1,2‐diyl)bis[3‐(2‐nitrophenyl)prop‐2‐en‐1‐imine]} in a 1:1 molar ratio in dichloromethane without exclusion of air or moisture resulted in the formation of the title complex μ‐chlorido‐μ‐hydroxido‐bis(chlorido{(1E,1′E,2E,2′E)‐N,N′‐(ethane‐1,2‐diyl)bis[3‐(2‐nitrophenyl)prop‐2‐en‐1‐imine]‐κ²N,N′}copper(II)) dichloromethane sesquisolvate, [Cu₂Cl₃(OH)(C₂₀H₁₈N₄O₄)₂]·1.5CH₂Cl₂. The dinuclear complex has a folded four‐membered ring in an unsymmetrical Cu₂OCl₃ core in which the approximate trigonal bipyramidal coordination displays different angular distortions in the equatorial planes of the two Cu^II atoms; the chloride bridge is asymmetric, but the hydroxide bridge is symmetric. The chelate rings of the two Nca₂en ligands have different conformations, leading to a more marked bowing of one of the ligands compared with the other. This is the first reported dinuclear complex, and the first five‐coordinate complex, of the Nca₂en Schiff base ligand. Molecules of the dimer are associated in pairs by ring‐stacking interactions supported by C—H…Cl interactions with solvent molecules; a further ring‐stacking interaction exists between the two Schiff base ligands of each molecule.     

The behaviour of copper and thallium hexafluoromolybdates(V) in acetonitrile

Copper(I), copper(II), and thallium(III) hexafluoromolybdates(V), prepared by the oxidation of the metals in acetonitrile with molybdenum hexafluoride (A. Prescott, D.W.A.Sharp, and J.M. Winfield, $\text{J. Chem. Soc., Dalton Trans.}$, 1975, 963) have been investigated by cyclic voltametry. Half wave potentials, E_{$\text{1}\text{2}$} V vs. Ag^p+/Ag were obtained using a evacuable cell equipped with anexternal Ag^p+/Ag electrode, enabling strict anerobic conditions to be maintained. A number of reversible or quasi-reversible electron transfer processes have been observed, enabling comparison with synthetic work to be made. Results for Cu^I and Cu^II hexafluoromolybdates(V) are in accord with preparative experience. MoF₆. Mo^VI/Mo^VE_{$\text{1}\text{2}$} +1.600V, oxidises Cu metal to Cu^II in MeCN, and Cu^II is reduced by Cu^O to Cu^I , Cu^lI/Cu^IE_{$\text{1}\text{2}$} = +0.750 or +0.710V for Cu^I and Cu^II solutes respectively, Cu^I/Cu^OE$\text{1}\text{2}$ = ?0.720V not reversible. A wave at E_{$\text{1}\text{2}$} = ?0.350V is assigned to Mo^V/Mo^IV by analogy with Ag^I hexafluoromolybdate (D.W.A. Sharp, unpublished work). E_{$\text{1}\text{2}$} data for I₂ in MeCN, I₂/I₃^- = 0.280, I₃^?/I^? = -0.116V, suggest that reduction of MoF₆^? by I is not likely, in contrast to the situation in SO₂ (A.J. Edwards and R.D. Peacock, $\text{Chem. Ind.}$, 1960, 1441). Reduction of MoF₆^? by Cu^o in MeCN should be feasible, but appears to be very slow. Pure Tλ^III hexafluoromolybdate(V) is obtained from Tλ^o and MoF₆ only when the mole ratio MoF₆:Tλ>5:1. Smaller ratios produce yellow solids in which Mo:Tλ is $\text{ca}$. 2:1. Tλ^III is a stronger oxidising agent than Cu^II in MeCN, as oxidation of Cu^I by Tλ^III is rapid and quantitative. However a reversible electron transfer wave assignable to Tλ^III/Tλ^I is not observed in the expected fange +1.600 to +0.710V possibly because of solute-electrode interactions.     

Crystal Structure and Properties of Strontium Phosphate Apatite with Oxocuprate Ions in Hexagonal Channels

Strontium phosphate apatites containing different amounts of copper were prepared by a solid state reaction at 1100 °C or by arc melting above 1600 °C in air. The samples were characterized by X‐ray diffraction, ICP analysis, scanning electron microscopy, IR spectroscopy, MAS—¹H—NMR, diffuse reflectance spectroscopy, and SQUID magnetometry. X‐ray crystal structure determination was carried out for a single crystal obtained from the melt. The compound is formulated as Sr₅(PO₄)₃(CuO₂)_1/3 and has an apatite structure (space group P6₃/m, a = 9.7815(4)Å, c = 7.3018(4)Å, Z = 2) with linear CuO₂^3— ions occupying hexagonal channels. For solid state synthesized samples, Rietveld refinement of powder XRD patterns was performed. The samples obtained at 1100 °C acquire the composition Sr₅(PO₄)₃Cu_xOH_y, with x changing from 0.01 to 0.62 and y < 1—x. The copper content can be increased to x = 0.85 by annealing in argon at 950 °C. The compounds represent a hydroxyapatite in which part of the protons is substituted by Cu⁺ and Cu²⁺ ions. The ions form linear O—Cu—O units which are progressively condensed creating the Cu—O—Cu bridges on increasing copper content. IR and NMR data testify existence of OH groups, non‐disturbed and disturbed by neighboring Cu atoms. In the electron spectra, the samples exhibit absorption bands at 7800‐7900, 14200‐14500 and 17500‐17550 cm^—1, which were assigned to Cu²⁺ d‐electron transitions. By annealing the sample with x = 0.1 in oxygen at 800 °C copper is fully oxidized while retaining in channels in unusual for Cu²⁺ linear coordination.     

A Photoluminescent Copper(I) Complex with an Exceptionally High CuII/CuI Redox Potential: [Cu(bfp)2]+ (bfp=2,9-bis(trifluoromethyl)-1,10-phenanthroline)

Unprecedented stabilization of the copper(I ) oxidation state is demonstrated for the complex cation [Cu(bfp)₂]⁺ ( 1 ) due to the steric and electronic effects of the CF₃ groups (E_1/2(Cu^II/Cu^I)=+1.55 V vs. SCE). The redox existence range of the copper(I ) species is remarkably high at 2.77 V. It is emissive in solution at room temperature and shows great potential as a photocatalyst; in the excited state it is a very potent photooxidant.     

5-Nitro-1,10-phenanthroline bis(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylformamide-Κ′O)-bis(perchlorato) copper(II): synthesis,structural characterization,and DNA-binding study

The hexa-coordinated copper(II) complex [Cu(L)(DMF)₂(ClO₄)₂], where L = 5-nitro-1,10-phenanthroline, was synthesized and characterized. The X-ray crystal structure shows that the copper is coordinated by the two N-atoms of the 1,10-phenanthroline ligand plus four O-atoms, two from DMF ligands and two from the perchlorate anions. Thermal analysis showed that the complex was stable up to 285 °C. The interaction of the complex with calf thymus DNA was investigated using absorption and emission spectroscopic studies, and the binding constant (K _b) and linear Stern–Volmer quenching constant (K _sv) have been determined. Electrochemical characterization of the complex in acetonitrile showed a quasi-reversible one-electron exchange voltammogram for the Cu²⁺/Cu+ redox couple at ca. E _1/2 = −1.00 V (versus SCE) with ΔE = 200 mV and i _pc/i _pa ≈ 1.     

Phase Equilibria in the System CuO‐NiO‐P4O10 and Synthesis,Crystal Structure,and Characterization of the New Copper Nickel Oxide Phosphate Cu3NiO(PO4)2

The system CuO‐NiO‐P₄O₁₀ was investigated using a solid state reaction between CuO, NiO, and (NH₄)₂HPO₄ in quartz crucibles at 900 °C. The powder samples were characterized by X‐ray diffraction, TG/DTA, electrochemical measurements, IR, and UV/Vis spectroscopy. Single crystals of a new quaternary phase Cu₃NiO(PO₄)₂ were achieved by cooling the melted compound in a sealed, evacuated quartz ampoule. Cu₃NiO(PO₄)₂ crystallizes in the monoclinic space group P2₁/n (no 14) with a = 8.2288(2) Å, b = 9.8773(2) Å, c = 8.2777(3) Å, β = 107.82(2)°, Z = 4. The three‐dimensional framework consists of distorted tetragonal pyramides [Cu1O₅], distorted planar squares [Cu2O₄], octahedra [Cu3O₆], and [NiO₆] and [PO₄] tetrahedra. The TG‐DTA of the new phase showed an incongruent melting at 1055 °C. The open circuit voltage of this material was measured to determine the electrochemical properties. The measurement revealed an initial capacity of 236 Ah · g^–1 and a voltage plateau at 2.05 V. Furthermore, it was possible to identify the phase equilibria and to obtain the phase diagram at 900 °C.     

Hydroxo‐bridged Tetranuclear CuII Complexes: {[Cu(bpy)(OH)]4Cl2}Cl2 · 6 H2O and {[Cu(phen)(OH)]4(H2O)2}]Cl4 · 4 H2O

The blue tetranuclear Cu^II complexes {[Cu(bpy)(OH)]₄Cl₂}Cl₂ · 6 H₂O ( 1 ) and {[Cu(phen)(OH)]₄(H₂O)₂}Cl₄ · 4 H₂O ( 2 ) were synthesized and characterized by single crystal X‐ray diffraction. ( 1 ): P 1 (no. 2), a = 9.240(1) Å, b = 10.366(2) Å, c = 12.973(2) Å, α = 85.76(1)°, β = 75.94(1)°, γ = 72.94(1)°, V = 1152.2(4) ų, Z = 1; ( 2 ): P 1 (no. 2), a = 9.770(3) Å, b = 10.118(3) Å, c = 14.258(4) Å, α = 83.72(2)°, β = 70.31(1)°, γ = 70.63(1)°, V = 1252.0(9) ų, Z = 1. The building units are centrosymmetric tetranuclear {[Cu(bpy)(OH)]₄Cl₂}²⁺ and {[Cu(phen)(OH)]₄(H₂O)₂}⁴⁺ complex cations formed by condensation of four elongated square pyramids CuN₂(OH)₂L^ap with the apical ligands L^ap = Cl, H₂O, OH. The resulting [Cu₄(μ₂‐OH)₂(μ₃‐OH)₂] core has the shape of a zigzag band of three Cu₂(OH)₂ squares. The cations exhibit intramolecular and intermolecular π‐π stacking interactions and the latter form 2D layers with the non‐bonded Cl^– anions and H₂O molecules in between (bond lengths: Cu–N = 1.995–2.038 Å; Cu–O = 1.927–1.982 Å; Cu–Cl^ap = 2.563; Cu–O^ap(OH) = 2.334–2.369 Å; Cu–O^ap(H₂O) = 2.256 Å). The Cu…Cu distances of about 2.93 Å do not indicate direct interactions, but the strongly reduced magnetic moment of about 2.74 B.M. corresponds with only two unpaired electrons per formula unit of 1 (1.37 B.M./Cu) and obviously results from intramolecular spin couplings (χ_m(T‐θ) = 0.933 cm³ · mol^–1 · K with θ = –0.7 K).     

Crystal Structures,Magnetic Properties and Catecholase‐Like Activities of μ‐Alkoxo‐μ‐Carboxylato Double Bridged Dinuclear and Tetranuclear Copper(II) Complexes

One μ‐alkoxo‐μ‐carboxylato bridged dinuclear copper(II) complex, [Cu₂(L¹)(μ‐C₆H₅CO₂)] ( 1 )(H₃L¹ = 1,3‐bis(salicylideneamino)‐2‐propanol)), and two μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear copper(II) complexes, [Cu₄(L¹)₂(μ‐C₈H₁₀O₄)(DMF)₂]·H₂O ( 2 ) and [Cu₄(L²)₂(μ‐C₅H₆O₄]·2H₂O·2CH₃CN ( 3 ) (H₃L² = 1,3‐bis(5‐bromo‐salicylideneamino)‐2‐propanol)) have been prepared and characterized. The single crystal X‐ray analysis shows that the structure of complex 1 is dimeric with two adjacent copper(II) atoms bridged by μ‐alkoxo‐μ‐carboxylato ligands where the Cu···Cu distances and Cu‐O(alkoxo)‐Cu angles are 3.5 11 Å and 132.8°, respectively. Complexes 2 and 3 consist of a μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear Cu(II) complex with mean Cu‐Cu distances and Cu‐O‐Cu angles of 3.092 Å and 104.2° for 2 and 3.486 Å and 129.9° for 3 , respectively. Magnetic measurements reveal that 1 is strong antiferromagnetically coupled with 2J =‐210 cm^?1 while 2 and 3 exhibit ferromagnetic coupling with 2J = 126 cm^?1 and 82 cm^?1 (averaged), respectively. The 2J values of 1–3 are correlated to dihedral angles and the Cu‐O‐Cu angles. Dependence of the pH at 25 °C on the reaction rate of oxidation of 3,5‐di‐tert‐butylcatechol (3,5‐DTBC) to the corresponding quinone (3,5‐DTBQ) catalyzed by 1–3 was studied. Complexes 1–3 exhibit catecholase‐like active at above pH 8 and 25 °C for oxidation of 3,5‐di‐tert‐butylcatechol.