Extraction-Coulometric Determination of Copper as Copper(II) 8-Hydroxyquinolinate

Conditions were selected for the coulometric determination of copper(II) by titrating copper(II) 8-hydroxyquinolinate extracted to chloroform with electrochemically generated bromine. The procedure was tested on model solutions and samples of surface waters. The detection limit is 5 × 10^–7 M at a generation current and time of 1 × 10^–3 A and 10 s, respectively.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 5, 2005, pp. 504–506.Original Russian Text Copyright © 2005 by Shlyamina, Morozova, Anisimova, Budnikov.     

Synthesis and Catalytic Properties of Copper(II) 1-Aryl-5-Benzothiazolylformazanates

New copper(II) benzothiazolylformazane complexes were synthesized and immobilized on AN-18 anion exchanger. The influence of the composition of the coordination core of copper(II) benzthiazolyl-formazanates and temperature on their catalytic properties in decomposition of H₂O₂ and oxidation of Na₂S in aqueous solution was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 6, 2005, pp. 957–961.Original Russian Text Copyright © 2005 by Gorbatenko, Pervova, Lipunova, Maslakova, Lipunov, Sigeikin.     

Copper(II) ion hydrolysis in aqueous solution

A copper(II) ion-selective-electrode potentiometric method was used to determine the first and second hydrolysis constants of Cu²⁺. Special techniques prevented copper(II) hydroxide precipitation, and copper(II) carbonate and cipper(II) organic complexation during the titration of the experimental solution over the pH range 6.8–8.4. The large change in the total copper concentration during the titration due to adsorption of copper onto the vessel walls was accounted for by measuring the total copper concentration at each pH by atomic absorption spectrophotometry. The two hydrolysis constants were determined at 25°C in 0.7 and 0.05m NaClO₄ media. The measured stability constants are independent of the copper concentration and yield similar zero ionic strength values. Also, the stepwise equilibrium constants decrease as the ligand number increases.     

Influence of the Structure of the Organic Moiety of Copper(II) Porphyrins on Their Reactivity toward Acids

The acid-induced dissociation of copper(II) porphyrin complexes with a high degree of meso- and β-substitution in the ligand was studied. The copper(II) complexes with octaethylporphyrins containing 0, 1, 2, 3, and 4 meso-phenyl substituents were ranked with respect to the stability. Octaβ-alkyl and unsymmetrical meso-phenyl substitution affects not only the quantitative characteristics of dissociation of the complexes but also the kinetic relationships of the process.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 497–503.Original Russian Text Copyright © 2005 by Kosareva, Klyueva, Lomova, Suslova.     

Copper(II)-selective electrode based on dithioacetal

A PVC membrane electrode for copper ion based on 1,3-dithiane,2-(4-methoxy phenyl) as ionophore and o-nitrophenyl octyl ether as a plasticizer is demonstrated. The electrode exhibits a Nernstian slope of 29.5±1 mV per decade in a linear range of 3.0×10⁻⁶ to 5.0×10⁻² M for Cu²⁺ ion. The detection limit of this electrode is 1.0×10⁻⁶ mol/l. This sensor has a very short response time of about 5 s and could be used in a pH range of 4.0-7.0. High selectivity was obtained over a wide variety of metal ions. The proposed electrode was successfully applied as an indicator electrode for the potentiometric titration of copper ion with EDTA and for the direct determination of copper in river water.     

Synthesis and Physicochemical Study of Binuclear Copper(II) Chelates Containing an Asymmetric Exchanged Fragment

Series of novel binuclear copper(II) chelate complexes containing an asymmetric exchanged fragment were synthesized for the first time. The ligands were the products of condensation of salicylaldehyde derivatives and 1,3-diaminopropan-2-ol or carbonohydrazide. The compositions and structures of the complexes obtained were proved by elemental analysis, IR and ¹H NMR spectroscopy, and magnetochemistry. The antiferromagnetic exchange parameters 2J were determined in terms of the isotropic-exchange HDVV model. The structural effects of exchange channels on these parameters are discussed.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 376–379.Original Russian Text Copyright © 2005 by Lukov, Kogan, Novotortsev, Tupolova, Gevorkyan.     

Electrophilic Copper(II) → Metal(II) Substitution in Gelatin-Immobilized Copper(II) Hexacyanoferrate(II) Matrix Implants

Contact of thin layers of gelatin-immobilized copper(II) hexacyanoferrate(II) matrices with aqueous solutions of Co(II), Ni(II), Zn(II), and Cd(II) chlorides results in partial substitution of these ions for Cu(II) to give (dd)-heterobinuclear hexacyanoferrates(II) of copper(II) and the corresponding double-charged ion.     

Synthesis and Study of Copper(II) Complexes with Aspartic Acid,Serine, and Valine

Binary and ternary copper(II) complexes with aspartic acid (H₂Asp), serine (HSer), and valine (HVal) were prepared by electrochemical and chemical procedures. The purity of the compounds was confirmed by elemental and thermogravimetric analyses. According to the IR spectra, all the complexes contain a five-membered chelate ring in which the Cu(II) atom is bonded with the oxygen atom of the carboxy group and nitrogen atom of the amino group. This is also confirmed by the ESR spectra.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 541–544.Original Russian Text Copyright © 2005 by Kryukova, Frolov, Kolokolov, Bolotin, Panyushkin.     

Dehydration/Rehydration Processes and the Porous Structure of a Tris(Macrocyclic) Carboxylate Copper(II) Complex

We have established that the crystal hydrate of the tris(macrocyclic) complex of copper with carboxylate, with a porous structure, undergoes stepwise dehydration leading to a change in its crystal lattice structure; but even total dehydration does not lead to loss of porosity in the latter. We have studied the sorption characteristics of the dehydrated sample with respect to water, methanol, and hexane.__________Translated from Teoreticheskaya i Eksperimental’naya Khimiya, Vol. 41, No. 3, pp. 166–170, May–June, 2005.     

Kinetics and Mechanism of Reaction of Carbon Tetrachloride with Copper(0) in Dimethylformamide

Reaction of copper(0) with carbon tetrachloride in DMF was studied. In the absence of atmospheric oxygen, the oxidative dissolution of copper(0) occurs as one-electron transfer and gives rise to C₂Cl₂ and copper(I) complexes. Kinetic and thermodynamic parameters of the process are determined, and its mechanism was considered.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 7, 2005, pp. 1194–1198.Original Russian Text Copyright © 2005 by Egorov, Matyukhova, Anisimov.     

Copper(I) and copper(II) complexes of diamino-dithioether ligands

Summary Copper(II) salts were reacted with two diamino-dithioether ligands, i.e. 1,3-di(o-aminophenylthio)propane (abbreviated H₂L¹) and 1,2-di(o-aminophenylthio)xylene (abbreviated H₂L²). Mixtures of copper(I) and copper(II) complexes were obtained with Cl^– and ClO ₄ ^– counterions. The major products were the copper(I) complexes, which were obtained pure after recrystallisation from MeCN-MeOH. The ligands lose two protons from the amine functions to form copper(I) complexes of general formula [CuL]X, where X = ClO ₄ ^– or Cl^–. The complexes were oxidised to [CuL]X₂ with H₂O₂ in DMF. Cu(NO₃)₂ on the other hand gave [CuH₂LNO₃]NO₃.     

Copper(II) Cyanoacetate Polymer: Synthesis and Structure

A new copper carboxylate polymer with cyanoacetate anion as a ligand was synthesized and studied using X-ray diffraction, IR, and EPR spectroscopy. The crystal is tetragonal: a= 14.702(2) Å, c= 13.470(3) Å, Z= 8, space group I4₁/a, and R= 0.0634. The copper atoms in the centrosymmetric dimeric fragment have a square-pyramidal surrounding with the CuO₄N coordination core and are joined through four bidentate bridging anions of cyanoacetic acid Cu(1)"–O(1A) 1.931(4) Å, Cu(1)"–O(1B) 1.926(4) Å, Cu(1)–O(2B) 2.018(3) Å, Cu(1)–O(2A) 2.036(4) Å, and Cu(1)–N(1A)" 2.206(5) Å). The Cu···Cu" distance in the dimer is 2.709 Å. The copper atom is extended from the mean equatorial plane toward the axial nitrogen atom by 0.23 Å. EPR data confirm strong antiferromagnetic interaction (2J –275 cm^–1) between the copper(II) ions of the dimeric fragment, whereas the interaction between the dimers is significantly weaker (J< 0.3 cm^–1).     

Reaction of N,N-Dimethyl-N′-(2-hydroxybenzyl)ethylenediamine with Copper(II) in the Presence of Surfactants

The protolytic properties of N,N-dimethyl-N′-(2-hydroxybenzyl) ethylenediamine (HL) and its complexation with copper(II) in the presence of cationic (cetyltrimethylammonium bromide) and nonionic (Triton X-100) surfactants were studied by pH-metry, spectrophotometry, and mathematical simulation of the equilibria. Cetyltrimethylammonium bromide affects the H₂L₂ ⇄ 2HL equilibrium. Along with the protonated monomeric and dimeric species, triprotonated tetrameric species were revealed in surfactant solutions, as in aqueous solutions of isopropyl alcohol. The surfactants affect the complexation of HL with Cu(II). The 1 : 2 complex with the phenolate form in solutions of cetyltrimethylammonium bromide is formed in a more acidic medium (pH ∼5.5) compared to an aqueous solution of isopropyl alcohol (pH ∼11). The apparent stability constants of the complexes increase in the presence of surfactants, especially of cetyltrimethylammonium bromide.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 379–382.Original Russian Text Copyright © 2005 by Sal’nikov, Boos, Ryzhkina, Ganieva.     

Synthesis and Structure of Copper(II) Phosphonodithioite Complexes

A series of new complexes of CuBr with phosphonodithioites were prepared and characterized by NMR and IR spectroscopy. As shown by single crystal X-ray diffraction, diethyl tert-butylphosphonodithioite forms with CuBr a tetrameric cubane-like complex with the monodentate coordination of the organophosphorus ligand via the P atom.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 903–907.Original Russian Text Copyright © 2005 by Kursheva, Kataeva, Perova, Batyeva, Sinyashin, Freilich.     

Copper(II)-cetyltrimethylammonium chloride-chromal blue G ternary complex and its application to the spectrophotometric determination of copper(II)

A sensitive spectrophotometric method for the determination of copper(II) based on a ternary complex with chromal blue G, a triphenylmethane reagent in the presence of cetyltrimethylammonium chloride, is described. The sensitivity of color reaction between copper and chromal blue G has been greatly increased by the sensitizing action of cetyltrimethylammonium chloride, a cationic surfactant. The color development of the ternary complex can be utilized in the highly sensitive spectrophotometric determination of copper. The molar absorptivity of the binary complex between copper and chromal blue G ε_630nm = 9.56 × 10³liters · mol⁻¹ · cm⁻¹ is enchanced on ternary complex formation to ε_{542 nm} = 4.78 × 10⁴liters · mol⁻¹ · cm⁻¹. The ternary complex gave a maximal absorbance at 542 nm in the pH range 9.8–11. Beer's law is obeyed up to at least 1.2 ppm of copper. The maximal absorbance of the ternary complex was found to develop within 5 min and then it remains constant for several hours. The formation constant of the ternary complex is calculated to be 8.6 × 10¹⁰ under these conditions.     

Copper(II) complexes with aroylhydrazones

The coordination chemistry of copper(II) with tridentate aroylhydrazones is briefly discussed in this article. Two types of aroylhydrazones derived from aroylhydrazines and ortho-hydroxy aldehydes or 2-pyridine-carboxaldehyde have been used. The characterization of the complexes has been performed with the help of various physico-chemical techniques. Solid state structural patterns have been established by X-ray crystallography. In the solid state, structural varieties of these complexes are seen to range from monomeric, dimeric, polymeric and one-dimensional self-assembly via hydrogen bonds and π-π interactions. EPR spectroscopy and variable temperature magnetic susceptibility measurements have been used to reveal the nature of the coordination geometry and magnetic characteristics of these complexes.     

Synthesis, Crystal Structure and Properties of Polyamine Copper(II) Complexes

Two polyamine copper(II) complexes were synthesized by the reaction between N,N,N′,N′-tetrakis(2′-aminoethyl)propane-1,2-diamine hexahydrochloride and copper(II) perchlorate under almost the same conditions except for reaction temperature. The crystal structures of two complexes were determined by X-ray diffraction techniques, which shows that one of the complexes is unexpected and is a double chlorine or chloride-bridged dinuclear copper(II) complex formed by two diethylenetriamines, and another is a pentadentate mononuclear copper(II) complex composed of homo-protonated N,N,N′,N′-tetrakis(2′-aminoethyl)propane-1,2-diamine. The mechanism of the reaction leading to form the unexpected complex was discussed. The UV-visible spectra and cyclic voltammogram of the complexes were measured.     

Copper(II) fluoride-catalyzed N-arylation of heterocycles with halothiophenes

A novel, cheap copper(II) fluoride-mediated N-arylation of heterocycles with halothiophenes is described. The yield of the pyrazolylthiophene strongly depends on the nature of the initial thiophene. The molecular structure of 3,5-dimethyl-1-(5′-methyl-[2,2′]bithienyl-5-yl)-1H-pyrazole was studied by X-ray diffraction.     

Dynamics of Copper(II), Nickel(II), and Iron(III) Ion Exchange

The degree of utilization of the static exchange capacity of KU-2×8×12 cation exchanger with respect to copper(II), nickel(II), and iron(III) cations was considered as a function of the solution flow velocity through the column cross section.     

Copper(II) ion-selective microelectrochemical transistor

A device has been developed for the measurement of copper(II) ions (Cu²⁺) in aqueous medium. The device reported here is an electrochemical transistor which consists of two platinum electrodes separated by 100 μm spacing and bridged with an anodically grown film of polycarbazole. Polycarbazole film (undoped form) is observed to be highly selective for the Cu(II) ions. In a completed device, the conductivity of the polycarbazole film changes on addition of Cu(II) ions. The change in conductivity is attributed to the conformational changes in the polymer phase on occupation of the Cu(II) ions, without affecting electron/proton transfer. The device turns on by adding 2.5 × 10⁻⁶ M Cu(II) ions and reaches a saturation region beyond 10⁻⁴ M Cu(II) ion concentrations. In the above concentration range, the device response [I _D vs. log Cu(II) ion concentration] is linear. The selectivity of the device for other metal ions such as Cu(I), Ni(II), Co(II), Fe(II), Fe(III), Zn(II) and Pb(II) is also studied. Received: 6 April 1999 / Accepted: 20 August 1999