Substitutions of copper(II) carboxylates with Schiff bases

Substitutions of anhydrous copper(II) acetate with higher carboxylic acids in an equimolar ratio in refluxing toluene yield monosubstituted soluble derivatives, which undergo substitutions with Schiff bases (derived from salicylaldehyde and aniline or p-chloroaniline) to give mixed complexes of the general formula [Cu(OOCR)- (SB)] (HSB = Schiff base and R = C13H27, C15H31, C17H35 and C21H43). The products have been characterized by elemental analyses, electrical conductance, magnetic moment and spectral (i.r. and electronic) data. Cryoscopic molecular weight determinations indicate that the derivatives are dimers. The complexes are e.p.r. silent.     

Electrochemical synthesis of copper(II) carboxylates

A number of copper(II) carboxylates have been synthesized by anodic oxidation of copper. The reactions were found to proceed with current efficiencies of 0.95 to 1.00 eq./Faraday. Reaction products have been characterized by infrared spectral studies and analysis of copper.     

Extraction of bismuth in substoichiometric conditions

The extraction of bismuth has been investigated in dependence of dilution and stoichiometry, using the reagents 8-hydroxyquinoline, N-benzyl-N-phenylhydroxylamine, diphenylthiocarbazone and substituted carbamates. Stripping of bismuth from organic solutions of the respective chelates using ligands such as EGTA, thioglycollic acid and 2,3-dimercaptopropane-1-sulfonate was also studied. It has been demonstrated that the equations proposed for determining the range of quantitative substoichiometric extraction are valid in the case of bismuth only at concentrations above 10⁻⁵ M Bi. At further dilutions (10⁻⁶–10⁻⁸ M), which would be of major interest in devising analytical methods based on the substoichiometric radioisotope dilution technique for determining bismuth at the trace level, the equilibria are shifted in favour of the competing hydrolytic reactions, so that the extraction is quantitative only with ammonium tetramethylenedithiocarbamate present in excess.     

Structures of copper(II) complexes with dihydrobenzoxazine derivatives in chloroform

Copper(II) complexes CuL₂ (HL = 2-(2-hydroxyphenyl)-4,4-diphenyl-1,2-dihydro-4H-3,1-benzoxazine and 2-(2-hydroxy-5-nitrophenyl)-4,4-diphenyl-1,2-dihydro-4H-3,1-benzoxazine) in chloroform were studied by EPR and electronic absorption spectroscopy. It was found that the complexation involves the azomethine forms of the ligands, which are coordinated by the Cu atom through the phenol and azomethine fragments of both ligands. The electronic absorption spectra were decomposed into Gaussian components to determine the d-d transition energies. The parameters of the complexation were calculated in terms of the angular overlap model. The order of energy arrangement of the orbitals of the central atom was determined: $d_{x^2 - y^2 } \gg d_{xy} > d_{z^2 } > d_{xz} > d_{yz} $ .     

Self-assembled hydrogen-bonded coordination networks in two copper(II) carboxylates with 4-pyridylmethanol

The crystal and molecular structure of [Cu(nif)₂(4-PM)₂]·CH₃OH (1) and [Cu(2-Clbz)₂(4-PM)₂(H₂O)] (2), (where nif = niflumate anion, 2-Clbz = 2-chlorobenzoate anion and 4-PM is the 4-pyridylmethanol), have been determinated by X-ray crystallography. The Cu²⁺ cation in (1), is coordinated by two pairs of oxygen atoms from asymmetric bidentate niflumate anions and by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands in trans position forming an extremely elongated bipyramid. The Cu²⁺ cation in (2), is coordinated by a pair of oxygen atoms from monodentate 2-chlorobenzoate anions, further by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands and finally by a water oxygen atom forming a tetragonal-pyramidal coordination polyhedron. The molecules of both complexes in crystal structures are linked by O-H…O hydrogen bonds, which created a three-dimensional hydrogen-bonding networks. The Π-Π stacking interactions are also observed in crystal structures of complex 2. The spectral properties (IR and electronic spectra) of both complexes were also investigated.     

Pyrolytic decomposition of some even chain length copper (II) carboxylates

The products of the pyrolytic decomposition of some even chain-length copper (II) carboxylates from decanoate to octadecanoate inclusive have been identified, using a flow system, to be copper, carbon dioxide, a carboxylic acid and an odd chain-mength alkene. These products are similar to those reported for the decomposition of mercury (II) carboxylates. The unexpectedly low (less than unity) CO₂/soap ratio was attributed to the reduction of the CO₂ to carbon monoxide. The carboxylic acid was characterised by wet chemical tests, determining the melting points of the acid and its amide derivative and matching its IR spectrum with that of the authentic acid. Elemental analysis and wet chemical tests were employed for the identification of the alkene.The products of decomposition and mechanism proposed to account for the degradative route of the systems show that good quality thin solid copper oxide films may only be obtained from the decomposition of copper (II) carboxylates if the carrier gas is non-inert (e.g. oxygen).

---

Zusammenfassung Als Produkte der pyrolytischen, in einem Gasstrom vorgenommenen Zersetzung einiger Kupfer (II) -Karboxylate mit geradzahliger Kohlenstoffatomzahl der Kette (Dekanoat bis einschließlich Octadekanoat) wurden Kupfer, Kohlendioxid, eine Karbonsäure und ein Alken mit ungerader Kohlenstoffatomzahl identifiziert. Diese Produkte sind ähnlich denen, die bei der Zersetzung von Quecksilber (II) -Karbcxylaten auftreten. Das unerwartet niedrige CO₂/Seife-Verhältnis (kleiner als 1) wurde der Reduktion von CO₂ zu Kohlenmonoxid zugeschrieben. Die Karbonsäure wurde durch naße chemische Tests, durch Bestimmung des Schmelzpunktes der Säure und dem des Amidderivats und durch Vergleich des IR-Spektrums mit dem der authentischen Säure identifiziert. Elementaranalyse und naße chemische Tests wurden zur Identifizierung der Alkene herangezogen. Die Zersetzungsprodukte und der zur Erklärung des Abbaus des Systems vorgeschlagene Mechanismus zeigen, daß dünne feste Kupferoxidschichten in guter Qualität nur bei der Zersetzung von Kupfer (II) -Karboxylaten in nichtinertem Trägergas (z. B. in Sauerstoff) erhalten werden.

---

, , . , , . , . ( ) — . , , . . , , , , - - , , .

     

Thermal decomposition of some N-oxide complexes of cobalt(II), nickel(II) and copper(II) carboxylates

Thermal decomposition of mono pyridine N-oxide complexe; of cobalt(II), nickel(II) and copper(II) propionates and mono quinoline N-oxide complex of copper(II) ben zoate has been studied by TG and DTA techniques. These dimeric complexes are stable upto 350–380 K and decompose in two stages: (i) successive elimination of the two ligand molecules (mostly endothermic); and (ii) decomposition of the resulting anhydrous metal(II) carboxylates by an exothermic multistep process in air.

---

Zusammenfassung Die thermische Zersetzung der Monopyridin N-oxidkomplexe der Kobalt(II)-, Nickel(II) und Kupfer(II)-propionate sowie des Monochinolin N-oxidkomplexes von Kupfer(II)-benzoat wurden durch TG und DTA-Methoden untersucht. Diese dimeren Komplexe sind bis zu 350–380 K stabil und werden in zwei Stufen zersetzt: (i) sukzessive Eliminierung der zwei Ligandmoleküle (hauptsÄchlich endotherm); und (ii) Zersetzung der entstehenden wasserfreien Metall(II)carboxylate durch einen mehrstufigen exothermen Vorgang in Luft.

---

Résumé On a étudié, par TG et ATD, la décomposition thermique des propionates des complexes mono-pyridine N-oxyde de cobalt(II), de nickel(II) et de cuivre(II) ainsi que du benzoate mono-quinoline N-oxyde de cuivre(II). Ces complexes dimères sont stables jusqu'à 350–380 K et se décomposent en deux étapes: (i) élimination successive des deux moléculesligands (la plupart du temps endothermique); et (ii) décomposition des carboxylates anhydres des métaux(II) formés par un processus en plusieurs étapes dans de l'air.

---

-N- (II), (II) (II), -N- (II). 350–380 : (1) (2) .

---

---

The authors are thankful to Dr. R. K. Dewan, Head of the Chemistry Department, University of Jammu, Jammu for providing necessary facilities in the department. The authors are also indebted to Dr. O. P. Vig, Head of the Chemistry Department, Panjab University, Chandigarh for assistance provided. One of the authors (R. K.) is grateful to University Grants Commission, New Delhi for the award of Junior Research Fellowship.     

The zero-field-splitting parameter D in binuclear copper(II) carboxylates is negative

High-field, high-frequency electron paramagnetic resonance measurements performed on two binuclear copper complexes, [Cu(CH3COO)2]2(H2O)2 (1) and [Cu(CH3COO)2]2(pyrazine) (2), allowed a definitive determination of the sign of the zero-field-splitting parameter D. Contrary to literature reports, that parameter is negative in each complex.     

Extraction of cobalt(II) with 7-(1-decenyl)-8-quinolinol into chloroform

Extraction of cobalt(II) with 7-(1-decenyl)-8-quinolinol (HRql) into chloroform was examined. The best cobalt extraction occurs in the pH region 5.5–9. In this region several other cations are extracted. The values of K_ex and pH_0.5 for cobalt extraction were found to be ?8.6 and 3.19 respectively. The composition of the extracted complex was found to be Co(Rql)₃. Cobalt is poorly reextracted from Co-HRql complex into the aqueous phase, the best results were obtained using HCl as a stripping agent.     

Synthesis, characterisation and thermal analysis of copper (II) and chromium (II, III) hydrazine carboxylates

Copper(II) hydrazine carboxylate monohydrate, Cu(N₂H₃COO)₂·H₂O and chromium (II, III) hydrazine carboxylate hydrates, Cu(N₂H₃COO)₂·H₂O and Cu(N₂H₃COO)₂·3H₂O have been prepared and characterised by chemical analysis, IR, visible spectra and magnetic measurements. Thermal analysis of the copper complex yields a mixture of copper metal and copper oxide. Chromium complexes on thermal decomposition yield Cr₂O₃ as residue. Decomposition of chromium(HI) complex under hydrothermal conditions yield CrOOH, a precursor to CrO₂.     

Separation and determination of bismuth(III) and copper(II) diethyldithiocarbamates in chloroform with hydrobromic acid

Bismuth and copper diethyldithiocarbamates are extracted into chloroform. Bismuth is selectively re-extracted with 3 M hydrobromic acid and determined spectrophotometrically as a bromide complex at 376 nm. Bismuth can be determined in the presence of large quantities of copper and iron.     

Extraction of copper(II) and nickel(II) by nopinoquinone dioxime

In the research for a selective extractant for nickel a strained dioxime, β-nopinoquinone dioxime, has been studied in its extraction properties for copper(II) and nickel(II). Spectroscopic investigations (ESR and NMR) showed that both copper and nickel are extracted as a N,N-coordinated chelate. The extraction studies showed that the use of strained instead of aliphatic dioximes makes the extraction more convenient because of the higher extraction rate, but the selectivity for nickel above copper disappears.δ-nopinoquinone dioxime is easily converted into its furazan by treatment with 1N NaOH. This furazan is a rather weak ligand without significant extraction capacities.     

A convenient synthesis of copper(I) carboxylates

A simple procedure is described for the synthesis of aliphatic and aromatic copper(I) carboxylates by the reduction of copper(II) carboxylates with commercially available tin(II) 2-ethylhexanoate. In this way copper(I) acetate, benzoate and stearate have been prepared in good yield and purity from the corresponding copper(II) carboxylates.     

Interaction of copper(II) oxide with monobasic mineral acids under model conditions and in the presence of metallic copper

It was determined that the heterogeneous heterophase interaction of copper(II) oxide with concentrated solutions of mineral acids occurs under diffusion control and involves dissolution of the product (rate-limiting stage), imitation of the behavior of homogeneous reactions of simple types, and self-termination once the liquid phase of the system transforms to a saturated solution of the dominant product. The forming basic and neutral copper(II) salts in acidified solutions or suspensions easily and rapidly oxidize copper and its alloys.     

Extraction of copper(II) and nickel(II) by long-chain aliphatic dioximes

In the search for a selective nickel extractant symmetric dialkyl dioximes have been studied in the extraction of copper and nickel ions from ammoniaca     

Spectral and thermal characteristics of copper(II) carboxylates with fatty acid chains and their benzothiazole adducts

The carboxylato–Cu(II) complexes of type [Cu₂(RCOO)₄] and their benzothiazole adducts [Cu₂(RCOO)₄bt₂] (bt = benzothiazole, R = CH₃(CH₂) _n?2, n = 12, 14, 16, 18) form the main objectives of this study. The studied carboxylato–Cu(II) complexes are formed from dimeric units to polymeric chains (chromofor CuO₅). The structural changes are due to coordination of ligand (benzothiazole). The polymeric chains of carboxylato–Cu(II) complexes degraded to discrete centrosymetric tetracarboxylate-bridged dimmers (chromofor CuO₄N). These prepared compounds [Cu₂(RCOO)₄] and [Cu₂(RCOO)₄L₂] were submitted to measurements relating to spectral (IR, UV–Vis) and thermal properties (TG, DTA, DSC).     

Lewis acid-catalyzed, copper(II)-mediated synthesis of heteroaryl thioethers under base-free conditions

A Lewis acid (Ag(I), Ni(II), or Fe(II)) catalyzed, Cu(II)-mediated thiolation reaction between heteroarenes and thiols was achieved with good yield under base-free conditions. DMSO could serve as an effective methylthiolation reagent for the synthesis of heterocyclic methyl thioethers.     

Polynuclear Cu(II) complexes with hyperbranched polyester carboxylates

Polydentate carboxylate platforms based on polyester polyol Boltorn H, containing from 8 to 14 carboxy groups in terminal positions were obtained. A method of synthesis of Cu(II) polynuclear complexes with polyester carboxylates Boltorn H with a degree of substitution of 65 and 90% was developed.     

Effect of the type of crystal lattice in nickel(II) and copper(II) macrocyclic carboxylates on absorption of copper amine complexes from solutions

We have established that crystalline nickel-containing metal–organic frameworks (MOFs) bind the complex [Cu(NH₃)₄](ClO₄)₂ from acetonitrile solutions and do not react with [Cu(en)₂](ClO₄)₂. The MOF/copper ammine complex ratio in the products after reaching saturation is determined by the crystal lattice structures of the compounds, and increases from 1.2 (one-dimensional coordination polymer, 1D CP) to 3.2 (2D CP)and 3.9 (ionic MOF) moles of copper ammine complex per formula unit of sorbent. We have shown that it is possible to convert the bound ammine complex to nanosized copper(II) sulfide by treatment with sodium sulfide.