Synergistic extraction of cobalt(II) with resacetophenone oxime in the presence of heterocyclic nitrogen and organophosphorous compunds

Equilibrium distribution coefficients have been determined, for the extraction of cobalt(II) with resacetophenone oxime as a function of pH and reagent concentration at ambient temperature. RAPOX forms simple 12 chelate with cobalt(II). Synergistic extraction was observed with pyridine and its methyl derivatives and some organophosphorous compounds. From the extraction equilibrium data, the adduct formation constants of 12 chelate to adducting ligand adducts were evaluated.     

EPR-study of reversible oxygenation process of coordination compounds of cobalt(II) with S-substituted N1,N4-di(salicylidene)-isothiosemicarbazides

The reaction between molecular oxygen and coordination compounds of cobalt(II) with S-substituted N¹,N⁴-di(salicylidene)isothiosemicarbazides in dimethyl sulfoxide solution was studied by the EPR method. It was found that paramagnetic monomeric adducts and diamagnetic -peroxo-dimers are formed. The spin-Hamiltonian parameters of the EPR spectra of the initial cobalt complexes, as well as of the paramagnetic adducts were determined. The nature of the Co-O₂ bond is discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 2, pp. 230–234, March–April, 1987.     

Solvent extraction study of cobalt(II) with 8-mercaptoquinoline

Equilibrium distribution coefficients have been determined for the extraction of cobalt(II) with 8-mercaptoquinoline as a function of pH and reagent concentraton at ambient temperature. The extractable complex is a diadduct, i. e. two molecules of the reagent are coordinated to the cobalt(II) chelate. The adduct formation constant in chloroform and the overall formation constant in the aqueous phase have been determined. Pyridine and its methyl derivatives were found to enhance the extraction of Co(II) into chloroform in the presence of 8-mercaptoquinoline. From the extraction equilibrium data, the adduct formation constants of 12 chelate to nitrogen base adducts were evaluated. The special role of steric factors is discussed.     

Computational modeling of mixed-ligand cobalt complexes with <Emphasis Type="Italic">o</Emphasis>-quinone derivative of corannulene

The structure and energy characteristics of isomers of electrically neutral adducts of tetracoordinate cobalt complexes with o-quinone derivative of corannulene were studied quantum chemically within the density functional theory (DFT) in the UB3LYP*/6-311++G(d,p) approximation. It was shown that the framework rigidity of the redox-active ligand favors convergence of the energy levels of the high-spin and low-spin isomers of the complexes under study as compared to the o-benzoquinone-containing analogues. At the same time, steric strain in the corannulene moiety causes the stability of the adducts to reduce. A compound characterized by high stabilization energy and the ability to switch its spin states via valence tautomeric rearrangements was found by systematic variation of structural parameters of cobalt bis(chelate).     

Isonitrosopropiophenone as an ambidentate chelating agent in some transition metal complexes

Summary Isonitrosopropiophenonates of cobalt(III), cobalt(II), nickel(II) and palladium(II) have been synthesised and characterised. Isonitrosopropiophenonatonickel(II) exists as green and brown varieties, the green forming mono- as well as bispyridine adducts. The brown variety is obtained after removal of base from the adducts. I.r. data of the metal chelates suggest atrans-asymmetric structure involving N and O bonding for one form and atrans-symmetric structure involving either N or O bonding of the oximino-group for the other. The former is observed exclusively with isonitrosopropiophenonates of nickel(II) while the latter is common among the other metal chelates. The low magnetic moment of the mono-adduct is ascribed to super-exchange interaction between two metal ions through oxo-bridges in the dimer. Acis-octahedral structure has been assigned to the tris(isonitrosopropiophenonato) cobalt(III) on the basis of¹H n.m.r. data. Isonitrosopropiophenone forms mixed-ligand complexes of cobalt(III) with tetradentate Schiff bases such as SALEN,N,N-ethylenebis(salicylaldimine), and SALPN,N,N-1,3-propylenebis-(salicylaldimine), where the isonitrose group bonds through the nitrogen atom. These complexes have a N,N,N,O,O,O ligand environment. The imino-nickel(II) and -palladium(II) complexes are assigned atrans-symmetric square planar structure. Characterisation of the complexes was based upon elemental analyses, conductivity and magnetic moment, and i.r.,¹H n.m.r., and electronic spectra.     

High-spin adducts of redox active 2,4,6,8-tetrakis(<Emphasis Type="Italic">tert</Emphasis>-butyl)phenoxazin-1-one with tetrahedral cobalt(II) complexes

The complex formation between redox active 2,4,6,8-tetrakis(tert-butyl)phenoxazin-1-one (L) and four-coordinate Co(II) complexes, resulting in six-coordinate adducts (I) (C₇₇H₈₂N₁₂O₅Co) and (II) (C₃₈H₄₁NO₆F₁₂Co) was studied. High-spin structure of the formed cobalt adducts I and II (hs-Co^II–BQ) was established by X-ray diffraction analysis and magnetochemistry methods. Adducts I and II are stable over a wide temperature range (5–300 K) and are not involved in the redox process giving low-spin adducts (ls-Co^III–SQ) studied previously.     

Structure and magnetic properties of 2,4,6,8-tetra(<Emphasis Type="Italic">tert</Emphasis>-butyl)phenoxazin-1-one adducts with cobalt(II) salts

Complex formation reaction of redox-active 2,4,6,8-tetra(tert-butyl)phenoxazin-1-one with cobalt(II) chloride leading to the dimeric adduct has been studied. UV spectroscopy studies have revealed the equilibrium of the formed adduct with dissociated form of the complex in the acetonitrile solution. In the presence of ethylene glycol, the complex formation with cobalt(II) perchlorate has afforded the high-spin trimolecular adduct. Crystal structure of the obtained adducts has been studied by means of X-ray diffraction analysis.     

Computational modeling of mixed-ligand cobalt diketonate complexes with pyrene-4,5,9,10-tetraimine

Quantum-chemical modeling (DFT UB3LYP*/6-311++G(d,p)) of binuclear mixed-ligand cobalt diketonate complexes with pyrene-4,5,9,10-tetraimine has been performed. Equilibrium geometries and stabilization energies of all the electromeric forms of the studied adducts have been calculated, and the exchange spin coupling constants have been evaluated. Compounds capable of undergoing one- or two-step valence tautomeric rearrangements accompanied by a change in magnetic properties have been revealed by varying the substituents in the bis(chelate) moiety.     

Synthesis,characterization and a thermogravimetric study of copper,cobalt and tin mono- and bis-adducts with ethyleneurea,ethylenethiourea and propyleneurea

This paper describes the synthesis, characterization and a thermogravimetric (t.g.) study of 11 adducts of general formula MCl₂·nL (M = Cu, Co and Sn; n = 1 and 2 for Sn, and 2 for Cu and Co; L = ethyleneurea eu, ethylenethiourea etu, and propyleneurea pu). The i.r. results shows that the eu and pu adducts are coordinated through oxygen, whereas for etu nitrogen is the coordination site. The (C=O) or (C=S) trend is: Cu > Co > Sn. The t.g. curves show that the adducts release ligand molecules in a single mass loss step. As regards considering adducts with the same stoichiometry, the observed thermal stability trend is: etu > pu > eu.     

Metal complexes of phytohormones. Part IV. Interactions of tetrakis-μ-acetato dirhodium(II) with 6-furfurilaminopurine, 6-benzylaminopurine, 6-furfurilaminopurine riboside and 6-benzylaminopurine riboside

Summary Interactions of tetrakis--acetato-dirhodium(II) with purine-derived ligands of biological interest such as the cytokinins 6-furfurilaminopurine (K), 6-benzylaminopurine (BAP), 6-furfurilaminopurine riboside (KR) and 6-benzylaminopurine riboside (BAPR) have been studied by means of magnetic susceptibility measurements at room temperature, i.r. and electronic spectroscopy and thermogravimetric analysis 11 metal:ligand adducts were obtained with all ligands; in addition 12 adducts were obtained with KR and BAPR. The most plausible structure for the 11 adducts is a polymeric bridging one, involving both axial positions of the Rh^II dimer and two N-sites of the purine moiety; for the 12 adducts only one N-site is involved.     

Phasentransferkatalysatoren auf Basis von Saccharose-Ethylenoxid-Addukten

Sucrose ethyleneoxide adducts have been prepared by reaction of sucrose with various amounts of ethyleneoxide inDMSO. The resulting polypode molecules were found to be efficient phase transfer catalysts in nucleophilic substitutions, oxidation and dichlorcarbene generation. Polymerisable polypodes have been obtained by reaction of sucrose ethyleneoxide adducts with methacrylic anhydride or methacryloylchloride in pyridine. Free radical polymerisation of the resulting mixtures of mono- and polyfunctional methacrylic esters of sucrose ethyleneoxide adducts yielded crosslinked gels. These polymer-supported octopus-molecules were found to be efficient triphase catalysts.

     

Synthesis of nickel(II)-di(5-chloro-2-methylphenyl)carbazonate and its adduct formation with heterocyclic nitrogen bases

Summary The title complex has been synthesized and characterized by elemental and spectral analysis. The Ni^II chelate forms adducts with heterocyclic nitrogen bases, which were characterized spectrophotometrically in solution. Bidentate and unsaturated monodentate bases form hexacoordinate adducts with 11 and 12 metalligand stoichiometries, respectively, whilst saturated nitrogen bases form pentacoordinate adducts with 11 stoichiometry. The results are discussed in terms of basicities and steric properties of the bases.     

Styrene oxide DNA adducts: quantitative determination using <Superscript>31</Superscript>P monitoring

The reaction of styrene oxide, a potential carcinogen in humans, with DNA constituents has been used to develop an improved method for quantification of DNA adducts. To enable monitoring of DNA adducts caused by xenobiotics at physiological relevant levels, a robust, reliable and powerful method based on monitoring of phosphorus in nucleotides is described. An efficient enzymatic digestion step and a sample-preconcentration procedure are essential, and enable separation of alkylated nucleotides from the large excess of native nucleotides. The adducts are detected by means of the phosphorus signal measured at mass m/z=31 with an inductively-coupled-plasma mass spectrometer. Bis(4-nitrophenyl)phosphate (BNPP) serves as internal standard for quantification of the adducts. The absolute limit of detection, 45 fmol, corresponds to detection of three modified nucleotides among 10⁷ native nucleotides (the calculation is based on use of 50 g calf thymus DNA). An adduct formation ratio at the DNA of 3.6 adducts per 1000 nucleotides was measured, which is 75% lower than for reaction with monomeric 2-deoxy-nucleotides. In addition, a substantial amount of phosphate adducts were detected, but in DNA the rate of phosphate formation was lower than with monomeric nucleotides. Most probably these adducts escaped unnoticed when ³¹P-post-labelling was employed.     

High performance liquid chromatographic separation and UV determination of cobalt, copper iron and platinum in pharmaceutical preparations using bis(isovalerylacetone)ethylenediimine as complexing reagent

The reagent bis(isovalerylacetone)ethylenediimine(H₂IVA₂en) has been examined for HPLC separation and UV determination of cobalt, copper, iron and platinum using off-line precolumn derivatization and extraction in chloroform. The complexes of cobalt(II), cobalt(III), iron(II), iron(III) and the reagent have been subsequently separated on a Microsorb C-18 column. The complexes were eluted isocratically using ternary mixtures of methanol/water/acetonitrile. Detection was achieved by UV monitoring. Detection limits for Co(II), Co(III), Fe(II) and Fe(III) were 2.5–5.0 ng/injection, based on 0.5–1.0 g/ml with 5 l/injection. The concentration of cobalt(II) and cobalt(III) in aqueous solution have been determined. The presence of oxovanadium(IV), platinum(II), and nickel(II) did not affect the determinations. The HPLC method developed has been applied to the determination of cobalt, copper, iron and platinum in pharmaceutical preparations at the 30 g/g to 15 mg/g level and the obtained results were compared to those of atomic absorption spectrometry.     

Simultaneous determination of iron(III) and cobalt(II) withN-phenylcinnamohydroxamic acid and thiocyanate by extraction and spectrophotometry

Simple, precise, sensitive, and highly selective methods for the separate determination of iron(III) and cobalt(II) and for the simultaneous determination of both metal ions are described. Iron(III) and cobalt(II) react with thiocyanate in the presence ofN-phenylcinnamohydroxamic acid (PCHA) to form pinkish red and blue coloured complexes, respectively. Both the iron(III) and cobalt(II) complexes having stoichiometric composition of 122 (FeSCN^–PCHA) and 14 (CoSCN^–), respectively, are quantitatively extractable into ethylacetate from 0.5–1.5 M hydrochloric acid solutions. The spectra of iron(III) and cobalt(II) complexes in the visible region exhibit absorption maxima at 495 and 625 nm, respectively. The coloured systems obey Beer's law in the concentration range of 0.2–4.0g/ml of iron and 2–40g/ml of cobalt. The effects of foreign ions and of various experimental parameters were studied to establish the optimum conditions for the extraction and determination of iron and cobalt. The methods have been applied successfully to the analysis of blood, vitamin B₁₂, and standard steels for iron and cobalt.     

Adducts of methyl β,β-bis(trifluoromethyl)acrylate with nucleophiles and allylic rearrangement during their dehydrofluorination

A number of adducts of methyl ,-bis(trifluoromethyl)acrylate with various nucleophiles were synthesized. The boundaries of the allylic rearrangement of 2-substituted 3-trifluoromethyl-4,4-difluoro-3-butenoates, obtained by dehydrofluorination of the cited adducts, were investigated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1359–1362, October, 1985.     

Formation of Metal-Related Ions in Matrix-Assisted Laser Desorption Ionization

In a study of the metal-related ion generation mechanism in matrix-assisted laser desorption ionization (MALDI), crystals of matrix used in MALDI were grown from matrix- and salt-containing solutions. The intensities of metal ion and metal adducts of the matrix ion obtained from unwashed crystals were higher than those from crystals washed with deionized water, indicating that metal ions and metal adducts of the matrix ions are mainly generated from the surface of crystals. The contributions of preformed metal ions and metal adducts of the matrix ions inside the matrix crystals were minor. Metal adducts of the matrix and analyte ion intensities generated from a mixture of dried matrix, salt, and analyte powders were similar to or higher than those generated from the powder of dried droplet crystals, indicating that the contributions of the preformed metal adducts of the matrix and analyte ions were insignificant. Correlation between metal-related ion intensity fluctuation and protonated ion intensity fluctuation was observed, indicating that the generation mechanism of the metal-related ions is similar to that of the protonated ions. Because the thermally induced proton transfer model effectively describes the generation of the protonated ions, we suggest that metal-related ions are mainly generated from the salt dissolution in the matrix melted by the laser.

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Triphenylmethane Dye of Sulfophthalein Series Adducts with Polyvinylpyrrolidone and Their Use in Chemical Analysis

The reaction of polyvinylpyrrolidone with sulfophthalein dyes was studied by spectrophotometry. The dependence of pH_1/2of the formation of adducts on the concentration and molecular mass of polyvinylpyrrolidone was determined. The ratio of components in adducts was determined. The effect of electron-donor and electron-acceptor substituents in dyes on pH_1/2was studied. A procedure for determining polyvinylpyrrolidone in the Gemodez-H pharmaceutical was proposed.     

One-milliliter wet-digestion for inductively coupled plasma mass spectrometry (ICP-MS): determination of platinum-DNA adducts in cells treated with platinum(II) complexes

Platinum (Pt)–DNA adducts formed by the anti-tumor agent cisplatin are recognized by the DNA mismatch repair (MMR) system. To investigate the involvement of MMR proteins including hMLH1 in the removal of these adducts, we developed a mL-scale wet-digestion method for inductively coupled plasma mass spectrometry (ICP-MS). The detection limit was 0.01 ng mL^–1 Pt, which corresponded to 2 pg Pt/g DNA when 10 g of DNA was used. The mean relative errors were 5.4% or better for a dynamic range of 0.01–10 ng mL^–1 Pt. DNA (~500 g) had no matrix effect. To improve the accuracy, DNA preparations were treated with ribonuclease and the apparent reduction in the concentration of Pt was corrected using cellular DNA levels, which were determined with Hoechst 33258. No significant differences were observed, in terms of the formation of Pt–DNA adducts or their removal over 6 h, between hMLH1-deficient HCT116 cells, a human colorectal cancer cell line, and hMLH1-complemented HCT116+ch3 cells (n=5; P>0.05), indicating that the hMLH1-dependent DNA repair systems contribute to neither the formation nor the removal of the adducts at detectable levels. In addition, approximately 19% of the adducts were removed within 6 h in both cell lines. A time course analysis (~24 h) suggested that the removal of cisplatin-generated Pt–DNA adducts follows first-order kinetics (t_1/2=32 h). The amount of Pt–DNA adduct formed by oxaliplatin in 1 h was 56% (ratio of means) of that generated by an equimolar concentration of cisplatin in HCT116. The proposed procedure could be useful for determining Pt–DNA adducts formed by Pt(II) complexes.     

Synthesis and Polymerization in Unsaturated Co β-Diketonates

Polymerization of some unsaturated -diketonates of cobalt containing double bonds both unconjugated and conjugated with a metal cycle. Unlike monomeric complexes, cobalt in metal-containing polymers was shown to have tetrahedral structure of the coordination polyhedron. The kinetic parameters of polymerization depend on electronic and steric properties of -diketonates.