Formation Of Cobalt Complexes Research Articles

DETERMINATION OF THE COMPOSITION AND STABILITY CONSTANT OF COBALT (II) POLYLIGAND CITRATE-MOLYBDATE COMPLEXES

The complex formation of cobalt (II) with citrate (cit3–) and molybdate (MoO42–) ions in 0.3 mol·l-1 Na2SO4 solution at 20°C was studied by spectrophotometric method. It has been established that in a citrate-molybdate electrolyte at pH 9.0, cobalt (II) ions form, depending on the ratio of the equilibrium concentrations of ligands: molybdate [Co(MoO4)2]2–, citrate [Co(cit)2]4– and polyligand complexes [Co(cit)m(MoO4)n]+2-(3m+2n). The composition of [Co(cit)(MoO4)]3– polyligand complexes was determined, the equilibrium constant Ke of the reaction of their formation and their stability constant (lgβMLX = 5.86) The dependence of the degree of formation of molybdate, citrate and polyligand complexes of cobalt (II) in citrate-molybdate electrolyte on the logarithm of the ratio of equilibrium concentrations of ligands was calculated.

Complex Formation of Cobalt(II) Ions with 4,4′-Bipyridine in Non-Aqueous Solvents

Complex Formation of Cobalt(II) Ions with 4,4′-Bipyridine in Non-Aqueous Solvents

Effect of cobalt complexes on cobalt oxide particles for the activation of peroxymonosulphate in textile wastewater treatment

This study provides a comparison of the chloride and nitrate anions, water and alcohol solutions in the formation of cobalt complexes, and their effect on the cobalt hydroxide polymorph formed and the subsequent impact on the catalytic performance of the resulting cobalt oxide. The formation of α- and β-cobalt hydroxide polymorphs as precursors to Co3O4 nanoparticles depended on the cobalt complex formed. In water only, the role of the anion on the phase of hydroxide polymorph is negligible. Annealed Co3O4 nanoparticles derived from the solvothermal synthesis of β-cobalt hydroxide using cobalt chloride hexahydrate dissolved in 100% alcohol performed better in sulphate radical-advanced oxidation of methylene blue than annealed Co3O4 particles derived from the hydro/solvothermal synthesis of α-cobalt hydroxide using cobalt nitrate hexahydrate dissolved in 50% alcohol. However, when impurities exist in samples produced from nitrate precursor salts, the performance of the α-cobalt hydroxide-derived Co3O4 noticeably improves. This study shows, for the first time, the relationship between the cobalt hydroxide polymorph and the catalytic performance of the resulting Co3O4.

Synthesis and X-ray crystallography of nonanuclear cobalt cluster and mononuclear cobalt complex: Effect of phosphine on the formation of cobalt complexes

Nonanuclear complex [Co{Co4(µ4-O)(1-methylimidazole-2-thiolate)6}2](BF4)2 and mononuclear complex [Co(bis(1-methyl-imidazol-2-yl)disulfide)2](BF4)2 were synthesized using almost the same method and characterized by X-ray diffraction study. Although almost the same method was used during synthesis, the presence and absence of phosphine produced the nonanuclear complex and mononuclear complex, respectively. In addition, the mononuclear complex has bis(1-methyl-imidazol-2-yl)disulfide that can be obtained from the oxidation of 1-methylimidazole-2-thiolate ligand. Therefore, phosphine ligand could prevent the oxidation of 1-methylimidazole-2-thiolate ligand.

Thiocyanate precursor impact on the formation of cobalt complexes: Synthesis and characterization

Two new thiocyanate complexes have been synthesized with two different thiocyanate anion sources using 1-(2-pyrimidyl)piperazine and CoCl2·H2O. These compounds were characterized by single X-ray diffraction, FTIR, UV–Vis and TGA–DTA. The antibacterial activity was also examined. The XRD showed that compounds 1 and 2 crystallized into monoclinic and orthorhombic systems, respectively. In compound 1, cobalt is surrounded by two isothiocyanate anions and two nitrogen-amides, while in compound 2 it is surrounded by four isothiocyanate ligands and a separate protonated amide. Different interactions packed the system through NH⋯S, NH⋯O and OH⋯S hydrogen bonds forming a ring. Gap energy determination revealed two diverse behaviors, the first being characteristic of a semiconductor and the second of an insulator. In the 10–500 °C range, the thermal behaviors were investigated and showed the decomposition of the two complexes with metal complexes residues. The antibacterial analysis presented a weak performance.

Kinetics, mechanism and synthesis of adduct formation of tetraaza Schiff base cobalt(II) complexes as donor with diorganotin(IV)dichlorides as acceptor

The kinetics and mechanism of the adduct formation of diorganotin(IV)dichlorides (R2SnCl2), where R = Ph, Me, Bu, with Co(II) tetraaza Schiff base complexes such as: [Co(appn)][N,N′-1,2-propylenebis(o-amino-α-phenylbenzylideneiminato) cobalt(II)] and [Co(cappn)]{[N,N′-1,2-proylenebis(5-chloro-o-amino-α-phenylbenzylideneiminato)cobalt(II)]}, were studied spectrophotometrically. The kinetic parameters and the rate constant values show the acceptor tendency trend for the diorganotin(IV)dichlorides as follows: Ph2SnCl2 > Me2SnCl2 > Bu2SnCl2. Adducts were separately synthesized and fully characterized by 119Sn NMR, IR, UV-Vis spectra and elemental microanalysis (C.H.N) methods. The trend of the rate constants for the adduct formation of the cobalt complexes with a given tin acceptor decreased as follows: Co(appn) > Co(cappn). The linear plots of kobsvs. the molar concentration of the diorganotin(IV)dichlorides, the high span of the second order rate costant k2 values and the large negative values of ΔS‡ suggest an associative (A) mechanism for the acceptor-donor adduct formation.II Moreover, [Co(aptn)][N,N′-1,3-propylenebis-(o-amino-α-phenylbenzylideneiminato)cobalt(II)] and [Co(captn)][N,N′-1,3- proylenebis-(5-chloro-o-amino-αphenylbenzylideneiminato)cobalt(II)] were synthesized and characterized but, their kinetics with R2SnCl2 were so fast that it was impossible to follow them using the conventional methods.

Complex Formation of Cobalt(II) and Nickel(II) with 2-Hydroxypropylene-1,3-diamine-N,N,N',N'-tetraacetic Acid

The complex-formation equilibria of 2-hydroxypropylene-1,3-diamine-N,N,N',N'-tetraacetic acid (H4L) with Co2+ and Ni2+ ions were studied. The stability constants of the complexes CoL2-, CoHL-, NiL2-, and NiHL- were estimated; the resulting data were compared with respective data for related compounds.

Transition Metal Complexes with Pyrazole Based Ligands

Abstract The complex formation of cobalt(II)-, nickel(II) and copper(II) sulphate hydrates with 3,5-dimethyl-1-thiocarboxamidepyrazole (HL) was studied. The influence of the anions on the course of the reactionwas also examined, using nickel(II) salts with various anions. Beside the NiSO 4 ·7H 2 O the reaction hasbeen carried out with Ni(OAc) 2 , Ni(CF 3 COO) 2 and Ni(SCN) 2 . Compounds with the following compo-sition were obtained: Co(L) 3 , Ni(L) 2 and [Cu(SCN)L] 2 . The structure of the ligand and the Co(L) 3 complex was determined by single crystal X-ray analysis, while that of the Ni(L) 2 was solved by anal-ysis of powder diffraction X-ray data. The most probable structure of the copper(II) complex is pro-posed on the basis of the elemental analyses data, FT-IR spectrometry and magnetic measurement.The thermal decomposition of the complexes was investigated by thermogravimetry, DSC andcoupled TG-MS measurements. In the case of the nickel(II) compound, a relatively stable intermedi-ate was detected in the 550–650 K temperature range. The composition of the intermediate,Ni(SCN)(NCS), was determined by FT-IR-spectrometry.

Investigation of A New Catalytic Reaction of Complex Formation of Cobalt (III) With Nitroso-R-Salt for the Determination of Microquantities of Phosphate-Ions

ABSTRACT The catalytic action of phosphate-ions on the reaction of complex formation of cobalt (III) with nitroso-R-salt in a weakly acid medium has been found. The dependence of the rate of the catalytic reaction on temperature, concentrations of reagents and catalyst, pH of the medium, as well as on the presence of some anion and non-ion surface-active substances and accompanying inorganic minerals was studied. The optimum conditions for the determination of 0.1 μg/ml PO3- 4 in water were determined. A technique for the determination of phosphate-ion impurity up to 9×10-5% in the high-purity sodium iodide and 2×10-4% cesium iodide used for the single crystals growth is suggested.

Metal Ion Interactions with some Antibiotic Drugs of Penicillin Family. Part-IV. Equilibrium Study on the Complex Formation of Cobalt(II), Nickel(II) and Zinc(II) with Ampicillin

Metal Ion Interactions with some Antibiotic Drugs of Penicillin Family. Part-IV. Equilibrium Study on the Complex Formation of Cobalt(II), Nickel(II) and Zinc(II) with Ampicillin

Studies on the Interactions of Biological Metal Ions with some Sulphonamide Drugs. Part-I Equilibrium Study on the Complex Formation of Cobalt(II), Nickel(II), Copper(II) and Zinc(II) with Sulphapyridine, Sulphadiazine and Sulphathiazole

Studies on the Interactions of Biological Metal Ions with some Sulphonamide Drugs. Part-I Equilibrium Study on the Complex Formation of Cobalt(II), Nickel(II), Copper(II) and Zinc(II) with Sulphapyridine, Sulphadiazine and Sulphathiazole

Metal lon Interaction with some Antibiotic Drugs of Penicillin Family. Part-1. Equilibrium Study on the Complex Formation of Cobalt(II), Nickel(II), Copper(II) and Zinc(II) with 6-Aminopenicillanic Acid

Metal lon Interaction with some Antibiotic Drugs of Penicillin Family. Part-1. Equilibrium Study on the Complex Formation of Cobalt(II), Nickel(II), Copper(II) and Zinc(II) with 6-Aminopenicillanic Acid

Complex formation of cobalt(II) and copper(II) with macrocyclic polyethers in propylene carbonate

Abstract By means of potentiometric and calorimetric titrations, the complex formation of Co 2+ and Cu 2+ with different crown ethers has been studied in propylene carbonate. 15C5-crown ethers form the most stable complexes with both cations. The reaction enthalpies and entropies measured for the complexation of both cations by different 18-crown-6 ligands were quite unusual. One possible explanation is the differences in the fluctuations of these ligands around the complexed cations.

Metal Complexes of some Peptide Derivatives. Part-VIII. Equilibrium Study on the Complex Formation of Cobalt(II), Nickel(II) and Zinc(II) with some Salicyloylamino Acids

Metal Complexes of some Peptide Derivatives. Part-VIII. Equilibrium Study on the Complex Formation of Cobalt(II), Nickel(II) and Zinc(II) with some Salicyloylamino Acids

Complex Formation of Cobalt(II), Nickel(II) and Zinc(II) with some Sulphonamides derived from Amino Acids

Complex Formation of Cobalt(II), Nickel(II) and Zinc(II) with some Sulphonamides derived from Amino Acids

Potentiometric Study on the Complex Formation of Cobalt(II) Ion with Ethylenediamine-N-acetic Acid, Diethylenetriamine, and Iminodiacetic Acid

Abstract The formation constants of Co(II)–ethylenediamine-N-acetate (edma), –diethylenetriamine (dien) and –iminodiacetate (ida) complexes were determined by potentiometric titration in 1.0 M NaClO4 solution at 25 °C. The following results were obtained. Edma: logβ101=7.51, logβ102=14.05: dien: logβ101=9.34, logβ102=16.89; ida: logβ101=6.54, logβ102=11.95, βpqr being the overall formation constant defined in the text. The relative effects of amino and carboxyl groups on the affinity of ligands to Co(II) ion are discussed.

Study of structure and activity of cobalt bromide complexes in the oxidation of alkylaromatic hydrocarbons

Catalytic activity of tetrabromocobalt(II) complexes and halo complexes of the type CoX2L2 respectively with ligands involving as donor atom, nitrogen, sulphur, phosphorus, arsenic, or antimony was studied in oxidation of alkylaromatic hydrocarbons. The preparation of the nitrogen compounds in the complex formation and in the elementary reaction stages was investigated. Highly catalytically active tetrahedral complexes of the types CoBr2-4 and (CoBr3OAc)2-. Triethanolamine-coordinated cobalt bromide and chloride complexes react in acetic acid or its anhydride with oxygen, the triethanolamine ligand being oxidized as well. In addition to their participation in the cobalt complex formation, nitrogen compounds influence the recovery of the active forms of the catalyst; they do not, however, affect the rate of dehalogenation of organic bromides.

Formation of cobalt complexes resulted from hydrogen abstraction from solvent by oxygen dependent homolysis of phenylethylcobaloxime

Formation of cobalt complexes resulted from hydrogen abstraction from solvent by oxygen dependent homolysis of phenylethylcobaloxime

Studies in the complex formation of metal ions with sugars : Part I. The complex formation of cobalt(II), cobalt(III), copper(II) and nickel(II) with mannitol

The complex formation of mannitol with cobalt(II), cobalt(III), copper(II) and nickel(II) in alkaline media (0.1 to 4 M potassium hydroxide) was studied by spectrophotometry. Cobalt(II) and cobalt(III) reacted with mannitol to form 1:1 complexes; the conditional constant (in 4 M potassium hydroxide) of the former complex was found to be 2.2·105. The reaction of copper(II) with the sugar gave two complexes. In the range 0.5–4 M potassium hydroxide and with the ligand in large excess, a CuM compound was formed; in mixtures with a small excess or with the reactants present in equimolar amounts, the species Cu 2M predominated. In 0.5 M potassium hydroxide, the conditional constant of the latter compound was found to be 6.3·10 7. The low stability of the nickel(II) complex(es) with mannitol made it impossible to draw any definite conclusions as to the composition of the species formed in alkaline medium.

The Composition and Formation of Cobalt Complexes with 1-Nitroso-2-naphthol

The Composition and Formation of Cobalt Complexes with 1-Nitroso-2-naphthol