Iron(II), cobalt(III), nickel(II) and copper(II) chelates of furan and thiophene azo-oximes

Summary Complexes of furan and thiophene azo-oximes with iron(II), cobalt(III), nickel(II) and copper(II) have been prepared and characterised. Iron(II), cobalt(III) and copper(II) complexes are diamagnetic in the solid state. The diamagnetism of the copper(II) chelates is suggestive of antiferromagnetic interaction between two copper centres.¹H n.m.r. spectral data suggest atrans-octahedral geometry for the tris-chelates of cobalt(III). Nickel(II) complexes are paramagnetic, in contrast to the diamagnetism of the analogous complexes of arylazooximes. The electronic spectra are suggestive of octahedral geometry for the iron(II), cobalt(III) and nickel(II) complexes, andD _4h -symmetry for copper(II). Infrared data indicate N-bonding of the oximino-group to the metal ions.     

A new selective and high affinity polymeric complexing agent for transition metal ions

Summary The synthesis and characteristics of a new chelating glycinohydroxamate-containing polymer resin is described. The functionality of the polymer is 1.76 mmolg^–1. The hydrogen capacity, water regain and adsorption capacities for iron(III), cadmium(II), cobalt(II), copper(II), nickel(II) and zinc(II) were measured at various pH values; uptake of the metal ions increased with pH and was quantitative above pH 3 for most of the metal ions. All cations studied showed high exchange rates towards the resin. The half saturation times for iron(III), cadmium(II), copper(II) and zinc(II) were all less than 1 min. The coordination behaviour of the resin was studied with the help of e.p.r., i.r., u.v. and potentiometry. The pK _a of the resin is 10.70 and the log value of the stability constants for iron(III), copper(II), lead(II), zinc(II), cobalt(II), manganese(II), cadmium(II) and nickel(II) were measured as 21.81, 19.50, 19.20, 18.59, 18.51, 18.46, 18.37 and 18.36, respectively, at 25 ° C and I = 0.2M KCl.     

Synthesis,characterization, fluorescence and redox features of new <Emphasis Type="Italic">vic</Emphasis>-dioxime ligand bearing pyrene and its metal complexes

A new vic-dioxime ligand, N,N′-bis(aminopyreneglyoxime) (LH₂), and its copper(II), nickel(II) and cobalt(II) metal complexes were synthesized and characterized by elemental analyses, IR, UVVIS and ¹H and ¹³C NMR spectra (for the ligand). Mononuclear complexes were synthesized by a reaction of ligand (LH₂) and salts of Co(II), Ni(II), and Cu(II) in ethanol. The complexes have the metal-ligand ratio of 1: 2 and metals are coordinated by N,N′ atoms of vicinal dioximes. The ligand acts in a polydentate fashion bending through nitrogen atoms in the presence of a base, as do most vic-dioximes. Detection of a H-bonding in the Co(II), Ni(II), and Cu(II) complexes by IR revealed the square-planar MN₄ coordination of mononuclear complexes. Fluorescent properties of the ligand and its complexes arise from pyrene units conjugated with a vic-dioxime moiety. Fluorescence emission spectra of the ligand showed a drastic decrease in its fluorescence intensity upon metal binding. The electrochemical properties of the complexes were studied by the cyclic voltammetry technique. The nickel complex displayed an irreversible oxidation process while the copper complex exhibited a quasi-reversible oxidation and reduction processes based on the copper Cu(II)/Cu(III) and Cu(II)/Cu(I) couples, respectively.     

Ion/Molekülreaktionen negativ geladener KomplexeSchiffscher Basen mit potentiellen Ligandmolekülen in der Gasphase

Ion/molecule reactions of four coordinateSchiff base complexes under negative ion chemical ionization conditions have been studied. The complex metal ions consisted of cobalt(II), nickel(II) and copper(II).Schiff base ligands with different donor strengths were employed. The gas mixtures used contained 90% methane and 10% of the gases O₂, NO or CO. The spectra showed intense molecular negative ions, formed by secondary electron capture processes. Secondary ions were formed via ion/molecule reactions between the parent molecular negative ion and added gas molecules to giveMLX ^–,X=O₂, NO, CO;L=Schiff base ligand,M=Co(II) or Ni(II). Consistent with former investigations, secondary ion formation was not found for the copper compounds. Influence of the central metal ion as well as the ligand donor strength on the ion/molecule reactions are discussed. From the results obtained a mechanism of the secondary ion formation is suggested.

     

Preparation and properties of a chelating resin containing the nitrosoresorcinol group

A macroreticular polystyrene-based chelating resin with the nitrosoresorcinol group as the functional group has been synthesized. The resin shows selectivity for copper(II), iron(III), and cobalt(II). The sorption behaviour of cobalt(II) is examined in detail, with the intention of using the resin analytically. Iron(III) and cobalt(II) are separated in a column operation by stepwise elution with oxalic acid solution and hydrochloric acid respectively.     

Structural elucidation of manganese(II), iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of a new multidentate dihydrazino quinoxaline derivative

Summary Manganese(II), iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of a new multidentate oxygen-nitrogen donor, bis(N-salicylidene)-2,3-dihydrazino-1,4-quinoxaline (H₂BSDHQ) were prepared and characterised by elemental analysis, conductance, thermal, spectral and magnetic data. H₂BSDHQ deprotonates to give a dibasic ONNO donor set in a trivalent iron(III) complex, which binds to the divalent metal ions in a bis-tridentate fashion, using two monobasic ONN donor sets, and resulting in polymeric complexes. Octahedral geometries are proposed for all these complexes, and preliminary studies show that they possess potential antimicrobial activity.     

Synthesis, characterization and antimicrobial activity of 3d transition metal complexes of a biambidentate ligand containing quinoxaline moiety

A new series of oxovanadium(IV), chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), and copper(II) complexes of the 3-hydrazino quinoxaline-2-one (HQO) were prepared and characterized. The ligand exhibits biambidenticity. It behaves as a bidentate ON donor in oxovanadium(IV), iron(III) and copper(II) complexes and as a bis bidentate ONNN donor in chromium(III), manganese(II), cobalt(II) and nickel(II) complexes. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, thermal, infrared, ¹H NMR, electronic spectra, magnetic susceptibility and conductivity measurements. An octahedral geometry was suggested for all the complexes. All the complexes show subnormal magnetic moments. The ligand, HQO, and its complexes were tested against one strain Gram +ve bacteria (Staphylococcus aureus), Gram −ve bacteria (Escherichia coli). The prepared metal complexes exhibited higher antimicrobial activities than the parent ligand.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 7. Chemical and antifungal properties of 2-acetylpyridine4 N-ethylthiosemicarbazone and its metal complexes

Summary Spectral and thermal information, as well as activity againstAspergillus niger, have been obtained for 2-acetylpyridine⁴ N-ethylthiosemicarbazone and its iron(III), cobalt(II,III), nickel(II) and copper(II) complexes.     

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.     

Determination of iron and copper in seawater at pH 1.7 with a new commercially available chelating resin, NTA Superflow

The use of a commercially available chelating resin with NTA-type functional groups for concentration of trace metals from seawater is described. Trace metal recoveries from this NTA Superflow chelating resin are pH dependent. At a pH of ≤2 only iron(III) and copper are quantitatively recovered from the resin. Iron(II) cannot be quantitatively recovered from this resin below a pH of 5. However, oxidation of acidified seawater samples (pH 1.7) with H₂O₂ prior to loading onto the resin has been demonstrated to allow quantitative recovery of total dissolved iron. Deferrioxamine and Rhodoturlic Acid, two commercially available siderophores were used to investigate the effect of strong Fe(III)-binding organic ligands on the ability to retain iron at different pH values. Acidification of seawater samples to pH 1.7 dissociates the iron complexed to these organic ligands, thereby allowing total dissolved iron and copper to be determined. Acidified samples from Monterey Bay were analyzed by a flow injection method coupled to ICP-SFMS detection using the NTA Superflow resin in the pre-concentration step. Results from this study show that when seawater samples are stored acidified (pH 1.7) over time, a portion of iron(III) is reduced to iron(II), thus necessitating the use of H₂O₂ to reoxidize the Fe(II) to Fe(III) prior to analysis. Total dissolved concentrations of iron and copper can be directly obtained on seawater samples at pH 1.7 with this method, eliminating the need to buffer the sample to a higher pH prior to column loading. This resin has the potential to be used in shipboard or in situ flow injection methods.     

Reaction of 1-chloro-2-phenylethane-2,2-dithiol with divalent metal (Cu, Hg, Pb, Fe, Co, and Ni) salts

Reactions of 1-chloro-2-phenylethane-2,2-dithiol with lead(II) acetate and mercury(II) chloride lead to 1-chloro-2-phenylethane-2,2-dithiolates of lead and mercury. The reactions with copper(II) chloride, iron(II) sulfate hydrate, cobalt (II) chloride hydrate, and nickel(II) acetate give metal-containing compounds C₁₆H₁₈S₄M. The¹H NMR, IR, and ESR spectra of the obtained compounds were recorded; their specific dark electroconductivities and activation energies of dark conductivity were determined, and their film-forming ability was studied. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1224–1226, June, 1997.     

Transition metal complexes of novel tridentate S,N,O donor ligands

Summary Complexes of chromium(III), iron(III), cobalt(III), nickel(II) and copper(II) with salicylaldehyde N(1-piperidyl) thiocarbonyl hydrazone (spthH₂), salicylaldehyde N-(1-morpholyl) thiocarbonyl hydrazone (smthH₂), 2-hydroxy 4-methyl acetophenone N-(1-piperidyl) thiocarbonyl hydrazone (apthH₂) and 2-hydroxy 4-methyl acetophenone N-(1-morpholyl) thiocarbonyl hydrazone (amthH₂) have been prepared and characterized by analytical, spectral and magnetic measurements. Mixed ligand complexes of Cu^II-thiocarbonyl hydrazones and heterocyclic bases have been isolated. Depending on the nature of the metal salts used and the reaction conditions the thiocarbonyl hydrazones act as neutral or dibasic tridentate ligands.     

Non-isothermal dehydration and decomposition of <Emphasis Type="Italic">dl</Emphasis>-lactates of transition metals and alkaline earth metals

A comparative study of the non-isothermal decomposition of the dl-lactate hydrates of magnesium, calcium and strontium has been made with that of the dl-lactate hydrates chromium(III), manganese(II), iron(II), cobalt(II), nickel(II), copper(II) and zinc(II) keeping dry air as the purge gas and the heating rate maintained at 10 K min^-1. While the dl-lactates of manganese(II), cobalt(II) and copper(II) followed single step decomposition scheme suggesting that dehydration and decomposition steps overlapped, the dehydration steps of the other compounds were distinct. &agr;-T plots of none of the dehydration steps showed any induction period, indicating no physical desorption, nucleation or branching. Neither the &agr; _max-values nor the onset temperatures of the dehydration steps did show any pattern. The TG data of the dehydration steps have also been analyzed using the Freeman-Carroll, Horowitz-Metzger, Coats-Redfern, Zsak&oacute;, Fuoss-Salyer-Wilson and Karkhanavala-Dharwadkar methods. Values of order of reaction, activation energy and Arrhenius factor have been approximated and compared. There are similarities in the activation energy values for the dehydration steps (&lt; 60 kJ mol^-1 in general). It is higher with group 2 metals and lower in transition metals (maximum in magnesium and lowest in chromium and iron lactates). In cases of overlapping of dehydration and decomposition steps, the activation energy values are on the lower side with the same trend (lower in cobalt and copper cases).     

Synthesis and Characterization of a New (E,E)-Dioxime and its Homonuclear Complexes

N′-(4′-Benzo[15-crown-5]naphthylaminoglyoxime (H₂L) and its sodium chloride complex (H₂L·NaCl) have been prepared from 2-naphthylchloroglyoxime, 4′-aminobenzo[15-crown-5] and sodium bicarbonate or sodium bicarbonate and sodium chloride. Nickel(II), cobalt(II) and copper(II) complexes of H₂L and H₂L·NaCl have a metal–ligand ratio of 1:2 and the ligand coordinates through the two N atoms, as do most of the vic-dioximes. The BF₂⁺-capped Ni(II), Co(III) and mononuclear complexes of thevic-dioxime were prepared. The macrocyclic ligands and their transition metal complexes have been characterized on the basis of IR, ¹H NMR spectroscopy and elemental analyses data.     

Solid State Conductivity and Catalytic Activity of Hexacyanoferrate(II)–Thiosemicarbazide Complexes of 3d-Metals

The temperature dependence of the resistivity of tablets of hexacyanoferrate(II)–thiosemicarbazide complexes of chromium(III), manganese(II), iron(III), cobalt(III), nickel(II), copper(II), and zinc(II) was measured in the range 20-90 °C. A relationship between the conductivity of a substance and the rate constant for the catalytic decomposition of hydrogen peroxide is established.     

Synthesis,characterization and catalytic studies of iron(III), cobalt(II), nickel(II) and copper(II) complexes containing triphenylphosphine and β-diketones

A series of new β-diketonato complexes have been synthesized from the reactions of iron(III), cobalt(II), nickel(II) and copper(II) Ph₃P complexes with β-diketones (acetylacetone, benzoylacetone and dibenzoylmethane). All the complexes have been characterized by elemental analyses, spectral studies (i.r., electronic., magnetic., e.p.r., ¹H-n.m.r.) and cyclic voltammetry. The new complexes have been used as catalysts for aromatic coupling and oxidation reactions. Higher catalytic activity has been observed for the nickel(II) complexes compared to the other complexes.     

A new binucleating ligand incorporating four oxime groups and its copper(II), manganese(II) and cobalt(III) complexes

A new binucleating ligand incorporating four oxime groups, butane-2,3-dione O-[4-aminooxy-2,3-bis-(2-hydroxyimino-1-methyl-propylideneaminooxymethyl)-but-2-enyl]-dioxime, (H₄mto), has been synthesized and its dinuclear cobalt(III), copper(II), and homo- and hetero-tetranuclear copper(II)–manganese(II) complexes have been prepared and characterized by ¹H- and ¹³C-n.m.r., i.r., magnetic moments and mass spectral studies. Elemental analyses, stoichiometric and spectroscopic data indicate that the metal ions in the complexes are coordinated to the oxime nitrogen atoms (C=N) and the data support the proposed structure for H₄mto and its complexes. Moreover, dinuclear cobalt(III) and copper(II) complexes of H₄mto have a 2:1 metal:ligand ratio.     

Highly sensitive spectrofluorometry of europium(III) as its benzoyltrifluoroacetone complex with trioctylphosphine oxide by means of solvent extraction and vacuum sublimation

Summary A new method for the highly sensitive fluorometric determination of europium(III) as its benzoyltrifluoroacetone (BFA) complex with trioctylphosphine oxide (TOPO) without uncombined BFA in n-hexane has been established by means of solvent extraction and vacuum sublimation. The effect of various factors on the fluorescence intensity of europium(III) was investigated. The fluorescence intensity was measured at 620 nm against rhodamine B as an internal standard under the excitation at 335 nm. It was found that a heating treatment gave rise to the enhancement of the fluorescence intensity for about twice times compared with that without heating treatment. Excellent linearity of the calibration curve of europium(III) was obtained in the range of 0–100 ppb. A few ppb of europium(III) can still be detected with this method. All 13 rare earth metals and cobalt(II) tested gave a somewhat positive error. Aluminium(III), iron(III), and copper(II) caused a negative error. The interference of aluminium(III) and iron(III) was removed by extraction with 0.1 mol/l 8-quinolinol in chloroform at pH 4.0, while the problem of cobalt(II) and copper(II) was solved by masking with 0.1 mol/l Na₂S₂O₃ in aqueous solution.

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Hochempfindliche spektrofluorimetrische Bestimmung von Europium(III) als Benzoyltrifluoracetonkomplex mit Trioctylphosphinoxid mit Hilfe der Lösungsextraktion und Vakuumsublimation

     

Synthesis, characterization and analytical application of a hydroxamic acid resin

A chelating ion-exchange resin with hydroxamic acid functional groups was synthesized from styrene-maleic acid co-polymer cross-linked with divinylbenzene. A resin prepared from equimolar amounts of styrene and maleic anhydride with 0.75 mole% divinylbenzene gives the best sorption characteristics. The selectivity of the resin for metal ions is copper(II) > cobalt(II) > zinc(II) > nickel(II) > manganese(II) > chromium(III) > iron(III) > vanadium(V). Copper(II), chromium(III) and iron(III) in chromium plating baths can be separated by use of the resin and determined spectrophotometrically.