Neutral Copper Research Articles

The effect of copper and zinc at neutral and acidic pH on the general haematology and osmoregulation of Oreochromis mossambicus

The objective of this study was to determine the effect of sublethal copper and zinc concentrations at a neutral and an acidic pH, on selected haematological parameters as well as on the total osmolality and electrolyte concentrations of Oreochromis mossambicus. In general, at neutral pH copper and zinc caused blood acidosis, increases in circulating white blood cell numbers, causing stimulation of the immune system, and a rapid release of red blood cells from haemopoietic tissue, as reflected in the decreases in mean corpuscular volume. Increases in red blood cells are attributed to an increase in the oxygen-carrying haemoglobin as an adaptation to altered respiratory homeostasis caused by copper and zinc. These increases are therefore a secondary reaction to the metals and not the result of direct stimulation of the haemopoietic tissue. In contrast, at an acidic pH copper and zinc concentrations usually caused blood alkalosis and decreases in white blood cell numbers, due to the bioconcentration of metals which blocks and suppresses the leucopoietic tissue. Decreases were also recorded in red blood cell counts, haemoglobin, haematocrit and mean corpuscular volume, which can be ascribed to anaemic and hypoxic conditions, gill damage and impaired osmoregulation.

Neutral metal complex in an ionic pocket: synthesis, physicochemical properties and X-ray structure of a copper(II) complex containing neutral as well as cationic dafone ligands and dafonium perchlorate

A neutral copper complex flanked by two protonated 4,5-diazafluoren-9-one (dafone, 1) ligands which are H-bonded with water molecules and perchlorate anions has been structurally and electrochemically characterized. The capped copper compound remains intact in solution, exhibiting a reversible Cu(II)/Cu(I) couple although undergoing a deformation along the Cu–N(2) axis and can serve as a good model of ionic pockets with metal active sites in some metalloproteins.

Optical emission spectra of a copper plasma produced by a metal vapourvacuum arc plasma source

Optical emission spectroscopy in the range 200-800 nm was appliedfor investigation of the copper plasma produced by a metal vapour vacuum arcplasma source. The experiments were conducted for the cases when the plasmawas guided by straight and Ω-shaped curved solenoids as well as withoutsolenoids, and also for different vacuum conditions. It was found that,besides singly- and doubly-charged ions, a relatively high concentration ofexcited neutral copper atoms was present in the plasma. The relative fractionof excited atoms was much higher in the region close to the cathode surfacethan in the plasma column inside the solenoid. The concentration of excitedneutral, singly- and doubly-ionized atoms increased proportionally when the arccurrent was increased to 400 A. Some weak lines were attributed to more highlyionized copper species and impurities in the cathode material.

Dioxygen activation by a neutral beta-diketiminato copper(I) ethylene complex.

The synthesis and structure of two thermally stable neutral beta-diketiminato copper(I) olefin complexes are presented along with the structure of a Cu(II)2(mu-OH)2 dimer that results from the reaction of the Cu(I) ethylene complex with O2 via the proposed intermediacy of a Cu(III)2(mu-O)2 species.

Copper(II) complexes of isomeric aminophenylhydroxamic acids. A novel ‘clam-like’ dimeric metallacrown and polymeric helical structure containing interlinked unique copper(II) sites

The reaction of 3-aminophenylhydroxamic acid with CuSO4·5H2O in aqueous solution gives the novel helical polymer [Cu3(3-Apha)4(H2O)SO4]n·8H2O 1 the structure of which contains interlinked repeating units having three unique neutral, anionic and cationic copper(II) sites. In this complex the copper(II) sites are magnetically non-interacting. A similar reaction with 2-aminophenylhydroxamic acid gives the novel dimeric ‘metallacrown’ [Cu5(2-AphaH−1)4(μ-SO4)(H2O)2]2·10H2O 2 which has a ‘clam-like’ structure showing strong antiferromagnetic behaviour. In contrast to the above ligands, 4-aminophenylhydroxamic acid gives the monomeric square planar complex Cu(4-Apha)2·H2O 3 which exhibits paramagnetic behaviour. Crystal structures of all three complexes are reported.

Copper(II) [(4-methylphenyl)sulfonyl]-1H-imino-(2-phenyl-2-oxazoline) complexes

Neutral copper complexes of the deprotonated [(4-methylphenyl)sulfonyl]-1H-imino-(2-phenyl-2-oxazoline) proligands, [HTs-ROz], R = H, 5-Me, 4-Me, 4-Et, 4-iPr, have been prepared by electrochemical oxidation of anodic copper in an MeCN solution of the corresponding proligand. The [Cu(Ts-ROz)2] complexes were characterised by microanalysis, i.r. and electronic spectroscopies, and by e.p.r. and magnetic measurements. The crystal structures of HTs-5MeOz, [Cu(Ts-Oz)2], [Cu(Ts-5MeOz)2] and [Cu(Ts-4MeOz)2] were determined by X-ray diffraction.

Synthesis and EXAFS investigation of azomethynic copper metallochelates with an N,S,O ligand environment

Neutral copper complexes of different composition (CuL 2 1 and CuL 2OAc) and structure were obtained by coupling the 1-phenyl(isopropyl)-3-methyl-4-( N-substituted)aldimino-5-oxy(thio, seleno)pyrazoles (HL 1), and 2-hydroxy(tosylamino)- N-(8-quinolyl)benzaldimine (HL 2) with copper(II) acetate. According to X-ray structural data, the CuL 2 1 complexes possess the pseudotetrahedral structure, and the CuL 2OAc complexes, the square-pyramidal one. The complexes were studied by EXAFS spectroscopy. EXAFS spectral data on the nearest ligand environment show a good correlation with the X-ray structural results.

Ferromagnetic Ordering in a Two-Dimensional Copper Complex with Dual End-to-End and End-On Azide Bridges This work was supported by the National Natural Science Foundation of China (NSF 29631040 and 29929001), The Major State Basic Research Development Program (Grant No. G2000077500 and No. G1998061306), and the Malaysian Government research grant R&D No. 305/pfizik/622004.

Long-range interactions are found in a neutral sheetlike copper compound in which each CuII ion is bridged by alternating end-on and end-to-end azide groups (see picture). Magnetic studies show unusual ferromagnetic interactions between CuII ions through both kinds of azide bridges in this complex (order at Tc=7 K), which is the first two-dimensional metal-azide-bridged compound with long-range ferromagnetic ordering properties.

Absolute densities of long lived species in an ionized physical vapor deposition copper–argon plasma

Optical absorption spectroscopy has been used to measure absolute, average gas phase densities of neutral copper, ground and metastable states, and neutral argon, metastable and resonance states, in an ionized physical vapor deposition plasma. Spectroscopic measurements were carried with a xenon arc lamp as a high intensity, continuum light source, and an optical multichannel detector. Copper radiative transitions in the wavelength range of 324.8–510.6 nm and argon radiative transitions in the 706.7–811.5 nm range were employed. The curve of growth method has been used to calculate the absolute line average densities from fractional absorption data. For a copper–argon plasma of neutral pressure 30 and 10 mTorr copper metastable state densities were found to lie in the range of 1010–1012 cm−3. Comparison of these densities with neutral copper densities derived from independent measurements of neutral copper flux at the substrate indicate gas phase temperatures greater than 1500 K under certain experimental conditions. These values of inferred temperatures indicate the copper metastable state density to be significant in comparison with neutral copper ground state densities at 10 and 30 mTorr with radio frequency heating power of 1 kW. The concentrations of argon 4s sublevels of the first excited state were found to be in the range of 4.5×108–1.5×1011 cm−3 for the experimental conditions studied. The ordering of the relative densities of the argon 4s sublevels and the variation of the lumped first excited state with experimental parameters are discussed.

A Fluxional α-Carbonyl Diazoalkane Complex of Copper Relevant to Catalytic Cyclopropanation

The neutral copper(I) ethylene complex [tBu2P(NSiMe3)2-κ2N]Cu(η2-C2H4) (1) reacts with diazophenanthrone (2), yielding an equilibrium mixture of 1 and 2 with free ethylene and the novel diazoalkane copper(III) complex 3, which represents a stabilized analogue of early intermediates in the mechanism of copper-catalyzed cyclopropanation reactions of electron-rich olefins with α-carbonyl diazoalkanes. Its X-ray structure determination displays square-planar coordination of the formally d8 copper(III) center with a κO:κN-bound diazophenanthrone. The geometry of the coordinated diazoalkane ligand can be directly compared to that of uncomplexed, cocrystallized diazophenanthrone, indicating a formal two-electron ligand reduction upon coordination. LT NMR spectroscopy reveals facile rotation of the diazoalkane ligand in solution even at temperatures below −110 °C. DFT calculations (B3LYP) on the model [H2P(NH)2-κ2N]Cu(N2CHCHO-κN:κO) (4) help to understand the bonding and fluxionality in 3 and predict a small liga...

Preparation of a chiral, 2-dimensional network containing metallacrown and copper benzoate building blocks.

Chiral metallacrowns have been fused into layers using neutral copper benzoate paddlewheel dimers and nitrate anions to link each 12-MC-4 molecule. The solid contains approximately 9 Å channels that are filled with solvent and a benzoic acid guest. A related chain structure that is generated by connecting metallacrowns with the copper dimer, but which does not have nitrate bridges in the second dimension, also has channels of similar size. These observations suggest a generalizable strategy for the preparation of microporous chiral solids in bulk quantities.

Si-O and P-O motifs in inorganic rings and clusters

This article presents a brief overview of different kinds of silanols and the important reactions of N-bonded silanetriols. The synthesis and characterization of silanediols containing Si-N and Si-C bonds, (2,4,6-Me3C6H2)N(SiMe3)Si(Me)(OH)2 (1e) is described. 1e shows a polymeric crinkled tape type of structure due to extensive intermolecular hydrogen bonding. We also describe the formation of a neutral copper(II) complex derived from the reaction of CuCl2 with (O)P(3,5-Me2Pz)3 where the ligand undergoes a facile P-N bond cleavage and functions as an N2O type of tridentate ligand.

Energy-resolved collision-induced dissociation of Cun+ (n=2–9): Stability and fragmentation pathways

Collision induced dissociation of Cun+ clusters (n=2–9) in collision with Xe is presented in the center-of-mass energy range from about 100 meV to above 15 eV. The collision energy dependence is measured for the total and the partial dissociation cross sections, and the dissociation thresholds for the dominating processes are derived. The threshold energies show pronounced odd–even alternations, reflecting a higher stability of the odd-numbered, Cu2n+1+, clusters. Further, the evaporation of a single neutral atom is found to be the energetically favorable process for the even-numbered clusters, while the loss of the neutral dimer is favorable in the case of the odd-numbered clusters. An exception is Cu9+, where the formation of Cun−1+ is energetically favorable, and the energetics of the Cun−2+ formation are in good agreement with sequential evaporation of two neutral monomers. Here we discuss the energy dependency of the total and partial dissociation cross sections, and try to give a consistent picture of the dissociation dynamics. We present binding energies for the cationic clusters from their dissociation thresholds, and use those, in combination with the literature values for the ionization potentials of Cun, to estimate the binding energies for neutral copper clusters. Finally, we compare this work to earlier theoretical calculations, as well as experimental estimations of the binding energies.

Chemistry of thiocarboxylates: synthesis and structures of neutral copper(I) thiocarboxylates with triphenylphosphine.

The reactions of Na+ R[O]CS- (R = Me, Ph) with mixtures of CuCl and PPh3 in stoichiometric ratios yielded the compounds [Cu4(SC[O]Me)4(PPh3)4] (1), [Cu4(SC[O]Ph)4(PPh3)3] (2), [Cu2(SC[O]Me)2(PPh3)4] (3), [Cu(SC[O]Ph)(PPh3)2] (4), and [Cu2(SC[O]Ph)2(PPh3)3] (5) quantitatively. Compound 2 was also obtained from mixtures of CuCl, PPh3, and NaSC[O]Ph in the ratio 1:1:1. The analogous thioacetate compound similar to 2 and the thiobenzoate analogue of 1 could not be obtained. Attempts to prepare the unsymmetrical dimer of a thioacetate compound similar to 5 gave a mixture of 1 and 3. The structures of 1-4 have been determined by single-crystal X-ray diffraction methods. Crystal data for 1: triclinic space group Pl, a = 11.5844(3) A, b = 13.2459(3) A, c = 14.3433(3) A, alpha = 64.019(1) degrees, beta = 79.297(1) degrees, gamma = 69.426(1) degrees, V = 1850.98(7) A3, Z = 1, Dcalcd = 1.439 g.cm-3. Crystal data for 2.0.5CH2Cl2.H2O: triclinic space group P1, a = 12.4413(1) A, b = 15.5443(1) A, c = 20.4637(3) A, alpha = 94.974(1) degrees, beta = 95.976(1) degrees, gamma = 100.450(1) degrees, V = 3848.09(7) A3, Z = 2, Dcalcd = 1.416 g.cm-3. Single-crystal data for 3: monoclinic space group P2(1)/n, a = 15.2746(2) A, b = 23.2947(2) A, c = 19.0518(3) A, beta = 96.713(1) degrees, V = 6732.5(2) A3, Z = 4, Dcalcd = 1.309 g.cm-3. Crystal data for 4: triclinic space group P1, a = 10.2524(3) A, b = 12.9826(4) A, c = 14.5340(4) A, alpha = 87.723(1) degrees, beta = 75.322(1) degrees, gamma = 75.978(1) degrees, V = 1815.14(9) A3, Z = 2, Dcalcd = 1.327 g.cm-3. Compound 1, [mu 3-SC[O]Me-S)2(mu-SC[O]Me-S)2(CuPPh3)4], is a tetramer with a distorted stepladder structure in which two copper atoms are trigonally coordinated and the other two are tetrahedrally coordinated. Two bonding modes, namely, mu 3-S and mu 2-S, were observed for the Me[O]CS- anion. The structure of 2 may be described as a highly distorted cubanoid structure and formulated as [(mu 3-SC[O]Ph-S3)(mu 3-SC[O]Ph-S2,O)3(Cu)(CuPPh3)3]. In 2, three copper atoms have tetrahedral coordination geometry and one copper atom is trigonally coordinated. Unprecedented bonding modes, namely, mu 3-S, have been observed for the R[O]CS- anions, in 1 and 2 and mu 3-S2,O in 2. Compound 3, [(mu-SC[O]MeS)(mu-SC[O]Me-S,O)[Cu(PPh3)2]2] is a dimer with mu 2-S and mu 2-S,O bonding modes of Me[O]CS- ligands. Monomeric structure was found in 4 in which the copper atom has trigonal planar geometry with a very weak intramolecular interaction with O. Variable temperature 31P NMR studies in solution show the presence of various species in equilibria.

Synthesis and characterization of the tetraazamacrocycle 4,10-dimethyl-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (H2Me2DO2A) and of its neutral copper(II) complex [Cu(Me2DO2A)]. A new 64Cu-labeled macrocyclic complex for positron emission tomography imaging †

The new macrocycle 4,10-dimethyl-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (H2Me2DO2A, H2L) has been synthesized and characterized. The basicity constants of the macrocycle and the stability constants of its complex formation with copper(II) ions have been determined in aqueous solution by potentiometry. The protonation sequence of the macrocycle has been studied by 1H and 13C-{1H} NMR spectroscopy. The data obtained are consistent with the first and second protonations taking place at the methyl-substituted nitrogen atoms, while the third and fourth protonations involve the two carboxylate arms. High-resolution NMR studies have revealed that the ethylenic protons in the tetraprotonated H4L2+species are inequivalent due to multiple hydrogen bonds within the macrocycle ring, indicating that the system is locked in a rigid conformation on the NMR timescale. The molecular structure of the copper(II) complex [Cu(Me2DO2A)]·2H2O has been determined by a single crystal X-ray analysis. The macrocycle wraps the metal in a distorted octahedral geometry using the four nitrogen atoms and two oxygen atoms from the two carboxylate groups. These latter are cis to each other. The excellent stability of [Cu(Me2DO2A)] at physiological pH is confirmed by a cyclic voltammetry study that shows the complex to be irreversibly reduced at Ep = −0.81 V. The radioactive 64Cu-labeled complex [64Cu(Me2DO2A)] has been synthesized using 64CuCl2. Animal biodistribution studies have been performed by bolus injection in rabbit and followed by Positron Emission Tomography (PET), an in vivo imaging technique used in nuclear medicine to detect the regional distribution and concentration of positron emitting radionuclides. PET images showed that the tested compound has high uptake in liver, kidneys and bladder. A significant uptake of radioactivity is observed in brain.

Ferro- and Antiferromagnetic Coupling through 1,n-Dithiosquarate Bridges (n = 2, 3) in Copper(II) Dimers. Syntheses, Crystal Structures, and Magnetic Properties of [Cu(2)(bpca)(2)(1,2-dtsq)(H(2)O)].2H(2)O and [Cu(2)(bpca)(2)(1,3-dtsq)].2H(2)O.

The preparation, crystal structures, and variable-temperature magnetic susceptibility data for two dithiosquarate-bridged copper(II) complexes of formulas [Cu(2)(bpca)(2)(1,2-dtsq)(H(2)O)].2H(2)O (1) and [Cu(2)(bpca)(2)(1,3-dtsq)].2H(2)O (2) (where bpca = the bis(2-pyridylcarbonyl)amide anion, 1,2-dtsq = dianion of 3,4-dimercapto-3-cyclobutene-1,2-dione, and 1,3-dtsq = dianion of 3-hydroxy-4-mercapto-2-thioxo-3-cyclobuten-1-one) are reported herein. 1 and 2 crystallize in the triclinic system, space group P&onemacr;, with a = 9.3243(4) Å, b = 10.9036(5) Å, c = 15.5432(4) Å, alpha = 90.276(2) degrees, beta = 100.009(2) degrees, gamma = 94.139(2) degrees, and Z = 2 for 1 and a = 7.656(2) Å, b = 9.351(3) Å, c = 11.587(2) Å, alpha = 109.02(2) degrees, beta = 97.40(2) degrees, gamma = 110.27(2) degrees, and Z = 1 for 2. Their structures consist of the neutral dithiosquarate-bridged copper(II) units [Cu(2)(bpca)(2)(1,2-dtsq)(H(2)O)] (1) and [Cu(2)(bpca)(2)(1,3-dtsq)] (2) and water molecules of crystallization. The copper environment is distorted square pyramidal CuN(3)SO in both compounds. Bpca acts as a tridentate end-cap ligand with its three nitrogen atoms occupying three of the four basal positions. 1,3-Dithiosquarate adopts a centrosymmetric bis-bidentate bridging mode with the sulfur atom filling the fourth equatorial position around each copper atom and the oxygen at the apical site. 1,2-Dithiosquarate acts also as a bridging ligand but in an asymmetrical manner, chelating through the two sulfur atoms at one copper atom and unidentate through one sulfur at the other copper atom. The bridging sulfur occupies one equatorial position at a copper atom and the apical site at the other one. The metal-metal separations through the extended 1,2- and 1,3-dtsq bridges are 5.1654(8) and 7.212(3) Å, respectively. The exchange pathways accounting for the intermediate ferro- (1, J = +32.4 cm(-)(1)) and antiferromagnetic (2, J = -33.5 cm(-)(1)) couplings (H = -JS(A).S(B)) observed in these dithiosquarate-bridged compounds are analyzed and discussed in the light of density functional theory (DFT) calculations.

Metal complexes with extended TTF dithiolato ligand: PTDT

Novel monoanionic, dianionic and neutral nickel, copper and palladium complexes with the extended TTF dithiolato ligand, propylenedithiotetrathiafulvalenedithiolate[ptdt 2−=(S 8C 9H 6) 2−], have been synthesized. The crystal structures of these complexes show the possibility of the electronic band formation by novel 2D or 3D intermolecular contacts through ptdt ligands. The single crystal of Ni(ptdt) 2 revealed an extremely high electrical conductivity(7 S cm −1) at room temperature as a neutral molecular crystal.

Determination of Thermodynamics and Kinetics of Point Defects in Cu2 O Using the Rosenburg Method

The Rosenburg method has been applied to determine physicochemical properties of at 900–1000°C and oxygen pressures from 0.005 to 0.1 atm. The defect concentration was proportional to , whereas the defect diffusion coefficient was essentially independent of the ambient oxygen pressure. This is interpreted to reflect that the dominating defect in is neutral Cu vacancies. The formation enthalpy of neutral copper vacancies was observed to be approximately 60 kJ/mol and the formation entropy approximately −11 J/mol K. Migration enthalpies and entropies have been calculated from the temperature dependence of the defect diffusion data and are approximately 54 kJ/mol and 5.8 J/mol K, respectively. Combination of the enthalpy of formation and migration of the vacancies yields an enthalpy for Cu self‐diffusion in of approximately 115 kJ/mol. © 1999 The Electrochemical Society. All rights reserved.

Potential Energy Curves and Electronic Structure of Copper Nitrides CuN and CuN+Versus CuO and CuO+

Ab initioconfiguration interaction calculations for the diatomic CuO, CuN, CuO+, and CuN+have been carried out, and potential energy curves are reported for several low-lying states of these systems. The electronic structure and bonding, not yet known for the neutral copper nitride and its cation, are examined and compared to those of the copper oxide systems. We find that the ground states of these systems areX2Π (CuO),X3Σ−(CuN),X3Σ−(CuO+), andX4Σ−(CuN+); their first low-lying excited statesY2Σ+,1Δ,1Δ, and2Π are located at 0.69, 1.45, 2.32, and 2.09 eV, respectively. For CuO we found two unobserved quartet states, namely4Σ−(Te= 1.09 eV) and4Π (Te= 1.86 eV). We report equilibrium structural parameters for various electronic states of the studied systems and compare them with experimental values, where it is possible.

Crystal structure and magnetic properties of the single-μ-chloro copper(II) chain [Cu(bipy)Cl 2] (bipy = 2,2′-bipyridine)

The crystal and molecular structure of the copper(II) chain [Cu(bipy)Cl 2] ( 1) (bipy = 2,2′-bipyridine) has been determined by X-ray diffraction methods. The crystal structure of 1 consists of neutral single chloro-bridged copper(II) chains with alternating short and long Cu–Cl distances through a screw axis parallel to a. The copper surrounding is best described as distorted square pyramidal, the equatorial plane being built by the two nitrogen atoms of the chelating bipy and two chlorine atoms (one terminal and the other bridging), whereas the apical position is filled by the bridging chlorine atom from the symmetry-related adjacent unit. The equatorial Cu–Cl bonds (2.291(3) and 2.259(3) Å) are shorter than the axial one (2.674(3) Å). The intrachain copper–copper separation is 4.010(3) Å whereas the shortest interchain copper–copper distance is 8.381(3) Å. The magnetic properties of 1 have been investigated in the temperature range 1.8–300 K. They reveal the occurrence of a weak intrachain antiferromagnetic coupling, J = −2.3 cm −1 (uniformly-spaced linear chain of local spin S = 1/2). This value is compared to those of related mono- and di-chloro-bridged copper(II) polymers and the available magneto-structural data are discussed in the framework of a simple orbital model.