Determination of Polyligand Complexes of Cobalt (II) with Citrate and Pyrophosphate Ions (original) (raw)
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Synthesis and Study of Cobalt Complexes
Journal of emerging technologies and innovative research, 2020
The origin of the name Cobalt is thought to stem from the German kabold for "evil spirits or goblins", who were superstitiously though to cause trouble for mines, since the cobalt minerals continued arsenic that injured their health and the cobalt ores did not yeild metals when treated using the normal methods. Metal ion complexes are playing an increasing role in the development of antimicrobials. In this research paper we study the antimicrobial properties of cobalt coordination complexes in oxidation state 3+. All complexes are found active when screen for their antimicrobial activity In UV-Vis spectrophotometeric study it is found that the, Hexamine cobalt (III) chloride absorbs at 240nm, Hexanitro cobaltate (III) absorbs at 228nm and hexanitro Co(III) absorbs at 222nm. Thermogravimetric analysis of Co(III) complex of Hexamine cobalt (III) chloride show mass at 80°c to 100°c is due to water lattice weight losses upon decomposition point shows thermal stability. In sodi...
Eclética Química Journal, 2019
Binary complexes of general formula CoCl2L2, where L = triphenylphosphine oxide (TPPO), benzyldiphenylphosphine oxide (BDPPO), dibenzylphenylphosphine oxide (DBPPO) and tribenzylphosphine oxide (TBPO) were considered concerning X-ray structural data for the complexes in the solid state and their stability constants in acetone solution. Compatibility between structural data and stability constants are pointed out. Previous investigations showed that in acetone medium, with CoCl2 as reference acceptor, the following basicity order is obeyed: TBPO > DBPPO > BDPPO > TPPO. This sequence is supported by X-ray diffraction data of the solid complexes and by electrolytic conductance values for these complexes both in acetone and in nitromethane media.
Journal of the Serbian Chemical Society, 2008
Four mixed-ligand cobalt(III) complexes (1-4) of the general formula [Co(Rdtc)cyclam](ClO 4 ) 2 and [Co(Rac)cyclam](ClO 4 ) 2 (cyclam = 1,4,8,11-tetraazacyclotetradecane; Rdtc = thiomorpholine-(Timdtc) or 2-methylpiperidine--(2-Mepipdtc) dithiocarbamates; Rac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionato (Hfac) or 2,2,6,6-tetramethyl-3,5-heptanedionato (Tmhd), respectively) were electrochemically examined on a glassy carbon and an iron electrode in perchloric acid solution. The obtained results showed the influence of these complexes on hydrogen evolution, the oxygen reduction reaction and iron dissolution. The exhibited effects of the complexes on these reactions depend on structure related to the bidentate dithiocarbamato or β-diketonato ligand. The electrochemical properties of the complexes were correlated with molecular structure and parameters derived from spectral analysis and molecular modeling.
Synthesis and Characterisation of Poly(Vinyl Pyrrolidon)-Cobalt(II) Complexes
The biological and industrial importance of many transition metals like iron, cobalt, copper etc., has been well studied. However, the attempts to employ inorganic salts of these metals in medical practice were not successful as most of them are highly toxic. In such cases Polymer-Metal Complexes can be used as substitutes both for addition and removal of metal ions into and out of a system. The use of water soluble polymer like poly (vinyl pyrrolidone), as a ligand, broadens the applications of these complexes. Polymer-metal complexes of poly (vinyl pyrrolidone) and cobalt were prepared by using aqueous solution of PVP (30K) and alcoholic solution of cobalt chloride hexahydrate (CoCl 2 • 6H 2 O) at room temperature with different molar compositions. The polymer-metal complexes were obtained in crystalline form by evaporation of the solvent. They were characterized by FTIR, 1 H-NMR with DMSO as solvent and 13 C-NMR. Procedure was repeated with aqueous solution of the salt also. The extent of complex formation was predicted by comparing the spectral data of the complexes with that of pure poly (vinyl pyrrolidone). The conditions for better complexation were optimized.
Journal of Molecular Structure, 2007
(2) [dpc is dipicolinate or pyridine-2,6-dicarboxylate, na is nicotinamide and ina is isonicotinamide], have been prepared and characterized by thermal analysis, IR spectroscopy and X-ray diffraction techniques. The complex (1) crystallizes in triclinic system, whereas the complex (2) crystallizes in monoclinic system. The Co(II) ion in both complexes is bonded to dpc ligand through pyridine N atom together with one O atom of each carboxylate group, two aqua ligands and N pyridine atom of na (1) or ina (2), forming the distorted octahedral geometry. The complex molecules (1) and (2) are connected via NAHÁ Á ÁO and OAHÁ Á ÁO hydrogen bonds. The voltammetric behaviour of complexes (1) and (2) was also investigated in DMSO (dimethylsulfoxide) solution by cyclic voltammetry using n-Bu 4 NClO 4 supporting electrolyte. The complexes exhibit only metal centered electroactivity in the potential ±1.25 V versus Ag/AgCl reference electrode.
Journal of the Serbian Chemical Society, 2003
The electrochemical properties of eight mixed-ligand cobalt(III) and cobalt(II) complexes of the general formulas [Co III (Rac)cyclam](ClO 4 ) 2 (1)-(4) and [Co 2 II (Rac)tpmc](ClO 4 ) 3 (5)-(8) were studied. The substances were investigated in aqueous NaClO 4 solution and non-aqueous LiClO 4 /CH 3 CN solution by cyclic voltammetry at a glassy carbon electrode. In aqueous solution, cyclam and Rac ligands being soluble in water undergo anodic oxidation. Coordination to Co(III) in complexes 1-4, stabilizes these ligands but reversible peaks in catohodic region indicate the redox reaction Co III /Co II ion. In the case of the binuclear Co(II) complexes 5-8, peaks recorded on the CVs represent oxidation of the bridged Rac ligand. The complexes examined influence the cathodic reaction of hydrogen evolution in aqueous solutions by shifting its potential to more negative values and its current is increased. In non-aqueous solution the CVs of the ligands show irreversible anodic peaks for cyclam, tpmc and for the Rac ligands soluble in acetonitrile. The absence of any peaks in the case of the investigated complexes 1-4 indicates that coordination to Co(III) stabilizes both the cyclam and Rac ligands. Cyclic voltammograms of the complexes 5-8 show oxidation processes of the Rac ligand and Co(II) ions but the absence of a highly anodic peak of the coordinated macrocycle tpmc shows its stabilization. Contrary to in aqueous solution, the redox reaction Co(III)/Co(II) does not occur in acetonitrate indicating a higher stability of the complexes 1-4 in this media in comparison with the binuclear cobalt(II)-tpmc complexes 5-8.
African Journal of Pure and Applied Chemistry, 2013
The preparation and isolation of complexes trans 1,2 diaminocyclohexane N, N, N', N'tetraacetato cobalt (III) [Co(CDTA)]-and ethylenediamine-tetraacetato cobaltate (III) [Co(EDTA)]-by direct oxidation of cobalt (II) with peroxodisulfate ion in the presence of Ag+ ion as a catalyst is being reported. The stoichiometry of the complexes has been confirmed through spectroscopic techniques i.e. UV-Visible, Infrared and Atomic Absorption Spectroscopy. The complexes were found to have similar analytical values, further to confirm the procedure the complex of Co (III) EDTA was first prepared, isolated and analyzed to confirm the structural formula, Co (CDTA)-was also studied as comparatively. The approach was set to characterize compounds as expected to have the molecular formula, K[Co(CDTA)}-xH 2 O in crystal form and [Co(CDTA}-in ionic form.
Journal of Molecular Structure, 2008
Cobalt(II) complexes of 6-hydroxypicolinic acid (6-OHpicH), namely [Co(6-OHpic) 2 (H 2 O) 2 ] (1) and [Co(6-OHpic) 2 (4-pic) 2 ]AE4-pic (2), and of 2-hydroxynicotinic acid (2-OHnicH), [Co(2-OHnic) 2 (H 2 O) 2 ] (3) were prepared. The crystal structures of free 6-hydroxypicolinic acid monohydrate 6-OHpicHAEH 2 O (4), and the novel polymorph of 2-hydroxynicotinic acid 2-OHnicH (5) and complex 2 were determined by X-ray crystal structure analysis. All compounds were characterized by IR-spectroscopy and thermal methods (TGA/DSC) and data are in agreement with the structure analysis. It was established that 4 and 5 exist in solid state in keto tautomeric form. For 2, structure analysis revealed N,O-chelating mode of 6-hydroxypicolinic acid.
Polyhedron, 2000
Several complexes with tosylamides were synthesised by the electrochemical oxidation of cobalt in an acetonitrile solution of [(4-methylphenyl)sulfonyl]-imino-1H-pyridine (HL) and the appropriate neutral coligand: L% (pyridine, 2,2%-bipyridine, 1,10phenanthroline or N,N-dimethylformamide). The structures of bis-(N,N-dimethylformamide)bis{[(4-methylphenyl)sulfonyl]-2pyridyl-amide}cobalt(II), bis-(pyridine)bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cobalt(II), 2,2%-bipyridine bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cobalt(II) and 1,10-phenanthroline bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cobalt(II) were determined by X-ray diffraction methods. In these monomeric complexes, the cobalt atom is in a distorted octahedral environment. The vibrational and electronic spectra of the complexes are discussed and are shown to agree with the structures.