Copper(II) and nickel(II) complexes of a neutral pentadentate Schiff base

A new pentadentate Schiff base 2,6,10-triaza-1,11-bis(2′-aminophenyl)-undeca-1,10-diene, abaDPT, and its complexes of general formula M(abaDPT)X₂ where M = Cu(II), Ni(II), X = Cl, Br, I, NO₃ and ClO₄, have been prepared. The complexes have been characterized by electronic and IR spectra, EPR, magnetic moments, molar conductances, and elemental analysis. IR data show an interaction between halide anion of the outer coordination sphere and the complexed amino group. EPR and spectrophotometric data of most of the copper compounds are consistent with a distorted square pyramidal geometry. Single crystal EPR studies of Cu(abaDPT)(NO₃)₂ and Cu(abaDPT)Br₂ revealed that copper atoms in the former compound occupy two magnetically inequivalent places in the lattice while copper atoms in the latter compound take identical sites. Principal g tensor axes of the two compounds have been determined.     

Studies on novel unsymmetrical azomethines—III : Copper(II) complexes of unsymmetrical tetradentate azomethines

Copper(II) complexes of unsymmetrical bifunctional tetradentate azomethines having the general formulae, (OC₁₀H₆CH:NXN:C(R)C₆H₄O)Cu, (OC₁₀H₆CH:NXN:C(CH₃)CHC(CH₃)OCu, (OC₆H₄CH:NXN:C(CH₃)C₆H₄O)Cu, (OC₆H₄C(R);NXN:C(CH₃)CHC(CH₃)O)Cu (where R = H or CH₃, X = (CH₂)₃, (CH₂)₄, (CH₂)₆ or -oC₆H₄) have been synthesized by the reactions of preformed mixed imine complexes of the type, CuLL′ (where L and L′ are two different imines such as 2-hydroxy-1-naphthaldimine, salicylaldimine, o-hydroxyacetophenonimine or acetylacetonimine) with diamines such as 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane or o-phenylenediamine. These complexes have been characterized by elemental analyses, TLC, conductance, magnetic measurements, IR and electronic spectra.     

Kinetics of the reaction of aluminum EDTA and cobalt(II) EDTA with calmagite

The reaction of aluminum EDTA with calmagite was found to be first-order in calmagite, half-order in aluminum EDTA, and zero-order in excess EDTA. The three-halves-order apparent rate constant at pH 9.48 and 20°C with ionic strength 0.30 was 0.232 ± 0.0141^{$\text{1}\text{2}$} · mol^{$\text{1}\text{2}$} · s^?1. The activation energy was 3.2 ± 0.3 kcal/mol. The pH dependence was complex between 8 and 10. The mechanism proposed is a rapid dissociation of a dimer of aluminum EDTA to a monomer followed by a rate-determining displacement of the EDTA by calmagite. The reaction of Co(II) EDTA with calmagite was confirmed to be first-order in Co(II) EDTA and first-order in calmagite with an activation energy of 7.5 ± 0.6 kcal/mol.     

Some complexes of nickel (II) with morpholine

The compounds NiX₂M_x[M = morpholine; X = C₆F₅ (x = 2), NO₃(x = 3), Br(x = 2 or 3), and I(x = 4)] have been prepared and investigated. Magnetic and spectral studies have been carried out to determine the mode of coordination and stereochemistry of the complexes. Except for NiBr₂M₃, which appears to contain bridging morpholine, in all other compounds the neutral ligand acts as a monodentate N-donor group.     

Kinetics of the reaction of Di-μ-acetatodi-μ-oxalatodiaquodiruthenium(II,III) anion with N-(2-hydroxyethyl)-ethylenediaminetriacetatoaquotitanium(III)

Reduction of [Ru₂(CH₃COO)₂(C₂O₄)₂(H₂O)₂]^? by N-(2-hydroxyethyl)-ethylenediaminetriacetatoaquotitanium(III) [Ti(HEDTA)] involves several distinct stages. The first stage has a half-time of less than 1 ms, and is interpreted as a substitution reaction leading to a multinuclear intermediate. The second stage has a second-order rate constant of 5 x 10₃M^?1s^?1 [25°C, μ = 0.1 m (LiCF₃SO₃)]. The rate-limiting process for the second stage is electron transfer within the assembled multinuclear complex. Subsequent slower stages correspond to breakup of the multinuclear Ru(II)₂-Ti(IV) complex formed by electron transfer. The overall rate of reduction of this oxidant by Ti(HEDTA) is less than the corresponding rate for the reaction in which Ti³⁺ acts as reductant, mainly because the stability of the binuclear complex is reduced by the presence of the aminoacid ligand. The data are consistent with the conclusion that the ligand increases the rate of intramolecular ET, probably by reducing geometric change associated with oxidation of Ti(III) to Ti(IV).     

Binuclear complexes of silicon(IV) chloride with nickel(II) salicylaldoximates

Some binuclear complexes of silicon(IV) chloride and nickel(II) salicylaldoximates were synthesized and characterised by elemental analyses, conductivity measurements, magnetic and spectral data. The complexes were proved to be 1:1 SiCl₄ adducts. The resulting complexes were amorphous in nature and electrolytes in solution.     

New nickel(II) chloride-morpholine complexes

The compounds [NiCl₂(Morph)₃(H₂O)₂] and [NiCl₂(Morph)₃] have been prepared by treating NiCl₂·6H₂O with morpholine (Mo     

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.     

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     

Preparation and characterization of copper(II) and nickel(II) complexes with novel tetraaza-macrocyclic schiff bases

Novel tetraaza-macrocycles with N-substituted carbamoyl groups were prepared by the reaction of 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,5,7,12-tetraene with isocyanates (RNCO, R = Ch₃ and C₆H₅). Their copper(II) and nickel(II) complexes were characterized by magnetic susceptibilities, electronic absorption spectra, and electrochemical properties. The complexing abilities and extractabilities of the ligands for the metal ions were investigated.     

A potentiometric study on the complex equilibria between nickel(II) and 2-mercapto-2-phenylacetic acid

Complex formation between nickel(II) and 2-mercapto-2-phenylacetic acid (H₂MPA) has been studied at 25°C and 1 mol dm^?3 ClO₄^? in     

Spectral and magnetic studies of tin(IV) complexes with nickel(II) thiocarbohydrazones

Tin(IV) chloride derivatives of nickel(II) thiocarbohydrazones were obtained by reacting tin(IV) chloride with nickel(II) thiocarbohydrazones in chloroform medium. All the complexes are greenish coloured solids and appear to be non-electrolytes in DMF. Elemental analyses conform to the 1:1 stoichiometry. Magnetic, electronic and IR spectral information suggest that square planar nickel(II) thiocarbohydrazones have changed their configuration to octahedral as a result of reaction with tin (IV) chloride.     

Reduction of the copper(II) cation in acetonitrile by trimethyl phosphite. Evidence for an intermediate copper(II) complex

Reduction of the solvated copper(II) cation by trimethyl phosphite in acetonitrile occurs via a short-lived purple intermediate believed to be a copper(II)-phosphite complex.     

Kinetics of the photoaquation of Hexacyanoferrate(II) ion

Kinetics of the photoaquation of hexacyanoferrate(II) ion in aqueous solution were studied potentiometrically and spectrophotometrically. Supposing the simplest mechanism (see Fig. 3. in text), the photoaquation in alkaline medium can be well described. The value of the constants at pH = ll.0 are: ø = 0.8-1.0, k₆ = (3.0 ± 0.5) × 10^?8 s^?1 and k_?6 = 1.5 ± 0.2 mol^?1 dm₃ s^?1. To describe the photoaquation in neutral medium t was extended (k′ = 3.33 x 10² mol^?1 dm³s^?1). The quantum yield in acidic medium can be calculated by combination of ø values of different protonated complexes. The reversibility of photoaquation in alkaline medium is also explained by the scheme.     

A new example of ligand-to-metal electron-transfer process : one-electron reduction products of nickel(II)-tetradentate schiff base complexes

The reduction of three nickel(III) complexes involving two symmetrical N,N′-ethylenebis (acetylacetoneiminato) and N,N′-ethylenebis (salicylideneiminato) and one non-symmetrical N,N′-ethylene (acetylacetoneiminatosalicylideneiminato) and Schiff bases has been investigated by electrochemistry and ESR spectroscopy. In all cases, exhaustive reduction results in the formation of nickel(I) complexes. However, ESR data support the formation of a nickel(II)-stabilized ligand radical species at the early stage of the reduction of the non-symmetrical Schiff base complex.     

A four-membered chelate complex of Cu(II) with creatinine

The complex formation between Cu(II) and creatinine was studied by means of electronic, IR and EPR spectroscopy. The spectral data show the formation of a Cu(II) four-membered chelate with distorted rhombic structure.     

Tetragonal distortions and vibronic coupling in hexaflouro nickel(II) and copper (II) complexes

Two parameters, axial (R_a) and equatorial (R_e) metal-ligand distances, describe the tetragonal distortions of the NiF^4?₆ and CuF^4?₆ complexes under study. The experimental values of R_a plotted vs R_e exhibit a smooth curve type dependence valid for MF₆ chromophore of solid state compounds. In the model study it becomes explained by analyzing the shape of the adiabatic potential surface (APS) of the form of E_T(R_a, R_e). Around the energy minima the map of numerical values (obtained by the quantum-chemical CNDOUHF and INDOUHF methods) was transformed to an analytic form from which the quantitative characteristics of APS were obtained in a new, simple way. The set of equatorial-axial parameters as well as the set of vibronic parameters were evaluated and discussed in more detail.     

A reappraisal of the nature of the product from the reaction of bis(methylcyclopentadieny)tin(II) with tungsten(cyclopentadienyl) (tricarbonyl) hydride

The nature of the product obtained from the title reaction has been reexamined, and identified as ClSn[W(CO)₃C₅H₅)]₃.     

Solvent extraction of copper(II), nickel(II), cobalt(II), zinc(II), and iron(Ill) by high molecular weight hydroxyoximes

The effects of pH have been examined on the extraction of the title ions by complexing with LIX-64N in kerosene. The extent of metal extraction as a function of pH is: Cu(II) < Fe(III) < Ni(II) < Zn(II) < Co(II). Stripping of all metal ions but cobalt with sulphuric acid from loaded kerosene complexing solutions is easily accomplished. Oxidation of Co(II) to Co(III) in the organic phase prevents stripping of this metal ion.     

Thermal reaction of aquaammineruthenium(III) complex with amino acid or imidazole derivative in the solid state

Intermolecular thermal-substitution reaction between aquaammineruthenium(III) complex and amino acid or imidazole derivative has been investigated in the solid state by the TG-DTA method. Pentaammineruthenium(III) complexes containing amino acid or imidazole derivative have been obtained directly by the thermal reactions. Glycine, β-alanine, and γ-aminobutyric acid coordinate to Ru(III) through their carbonyl oxygen, and imidazole does through its N(3) atom. Distinct coordination site is provided in the complex with histidine and/or adenine: the bonding site depends on the outer-sphere anion of aquaammine complex. The N(3) atom of the histidine and N(7) atom of the adenine coordinate to Ru(III) taking the paratoluenesulphonate salt of aquaammineruthenium(III) into the reaction. When the methanesulphonate salt is used, the nitrogen atom in the side-chain amino-group participates in complexation. Direct chelation of the glycine, histidine, and adenine to the deaquated cis-diaquatetraammineruthenium(III) complex has been confirmed.