Ligand Complexes Of Co Research Articles

Preparation and Antibacterial Activity of Mixed Ligand Complexes of Co(II), Ni(II), Cu(II) and Cd(II) Derived from 1‐Phenylazo‐2‐naphthol and Salicylaldehyde

The mixed ligand complexes of Co(II), Ni(II), Cu(II) and Cd(II) have been synthesized by using 1‐phenylazo‐2‐naphthol as primary ligand and salicylaldehyde as secondary ligand. All the prepared complexes were identified and confirmed by elemental analyses (C, H and N), molar conductance measurements, infrared, electronic absorption and electron paramagnetic resonance. The elemental analysis data suggest that the stoichiometry of the complexes to be 1:1:1[M: L1: L2] ratio. The molar conductance measurements of the complexes indicate their non‐electrolytic nature. The infrared spectral data showed the coordination sites of the free ligand with the central metal ion. The electronic absorption spectral data revealed the existence of an octahedral geometry for Co(II) and Cd(II) complexes and a square planar geometry for Ni(II) and Cu(II) complexes. The electron paramagnetic resonance spectra of the Co(II) and Cu(II) complexes showed the existence a paramagnetic phenomenon and supported their geometrical structures which confirmed by the electronic absorption spectra. The ligands and mixed ligand complexes have been tested on antibacterial activity against three strains of pathogenic bacteria such as Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa

Synthesis and characterization of mixed ligand complexes of cobalt(II) with some nitrogen and sulfur donors

Mixed ligand complexes of Co(II) with nitrogen and sulfur donors, Co(OPD)(S–S) · 2H2O and Co(OPD)(S–S)L2 [OPD = o-phenylenediamine; S–S = 1,1-dicyanoethylene-2,2-dithiolate (i-MNT2−) or 1-cyano-1-carboethoxyethylene-2,2-dithiolate (CED2−); L = pyridine (py), α-picoline (α-pic), β-picoline (β-pic), or γ-picoline (γ-pic)], have been isolated and characterized by analytical data, molar conductance, magnetic susceptibility, electronic, and infrared spectral studies. The molar conductance data reveal non-electrolytes in DMF. Magnetic moment values suggest low-spin and high-spin complexes. The electronic spectral studies suggest distorted octahedral stereochemistry around Co(II) in these complexes. Infrared spectral studies suggest bidentate chelating behavior of i-MNT2−, CED2−, or OPD while other ligands are unidentate in their complexes.

Synthesis, characterization and antimicrobial activities of some mixed ligand complexes of Co(II) with thiosemicarbazones and N-protected amino acids

The reaction of cobalt(II) chloride with a new class of thiosemicarbazones viz; cis-3,7-dimethyl-2,6-octadienthiosemicarbazone(CDOTSC; L1H) and 3,7-dimethyl-6-octenethiosemicarbazone (DOTSC; L2H) and N-phthaloyl derivative of DL-glycine(A1H), L-alanine(A2H) or L-valine(A3H) in 1:1:1 molar ratio in dry refluxing ethanol have been studied. All the isolated complexes have the general composition [Co(L)(A)]. Tentative structures are proposed for these complexes based upon elemental analysis, electrical conductances, magnetic moment, molecular weight determination and spectral (IR, electronic) studies.The ligands and Co(II) complexes have been tested for their antibacterial and antifungal activities against three bacterial strains S. aureus, B. subtilis, E. coli and two fungal strains F. moniliformae and M. phaseolina. Attempts have been made to establish a correlation between the antibacterial and antifungal activity and the structures of products.

Structural and equilibrium studies on mixed ligand complexes of Co(II), Ni(II), Cu(II) and Zn(II) with N-(2-benzimidazolyl)methyliminodiacetic acid and typical N, N donor ligands

Mixed ligand complexes: [Co(L)(bipy)] · 3H 2O ( 1), [Ni(L)(phen)] · H 2O ( 2), [Cu(L)(phen)] · 3H 2O ( 3) and [Zn(L)(bipy)] · 3H 2O ( 4), where L 2− = two –COOH deprotonated dianion of N-(2-benzimidazolyl)methyliminodiacetic acid (H 2bzimida, hereafter, H 2L), bipy = 2,2′ bipyridine and phen = 1,10-phenanthroline have been isolated and characterized by elemental analysis, spectral and magnetic measurements and thermal studies. Single crystal X-ray diffraction studies show octahedral geometry for 1, 2 and 4 and square pyramidal geometry for 3. Equilibrium studies in aqueous solution (ionic strength I = 10 −1 mol dm −3 (NaNO 3), at 25 ± 1 °C) using different molar proportions of M(II):H 2L:B, where M = Co, Ni, Cu and Zn and B = phen, bipy and en (ethylene diamine), however, provides evidence of formation of mononuclear and binuclear binary and mixed ligand complexes: M(L), M(H −1L) −, M(B) 2+, M(L)(B), M(H −1L)(B) −, M 2(H −1L)(OH), (B)M(H −1L)M(B) +, where H −1L 3− represents two –COOH and the benzimidazole N 1–H deprotonated quadridentate (O −, N, O −, N), or, quinquedentate (O −, N, O −, N, N −) function of the coordinated ligand H 2L. Binuclear mixed ligand complex formation equilibria: M(L)(B) + M(B) 2+ ⇌ (B)M(H −1L)M(B) + + H + is favoured with higher π-acidity of the B ligands. For Co(II), Ni(II) and Cu(II), these equilibria are accompanied by blue shift of the electronic absorption maxima of M(II) ions, as a negatively charged bridging benzimidazolate moiety provides stronger ligand field than a neutral one. Solution stability of the mixed ligand complexes are in the expected order: Co(II) < Ni(II) < Cu(II) > Zn(II). The Δ log K M values are less negetive than their statistical values, indicating favoured formation of the mixed ligand complexes over the binary ones.

Synthesis of mixed ligand complexes of CoIII

The synthesis and characterization of a series of mixed ligand complexes of Co I I I incorporating 1,3-diketones and the Schiff base derived from ethylenediamine and salicylaldehyde (H 2 Salen) have been reported. The complexes prepared are of the types 1,3-deketonato-OO'-[N,N'-ethylenebis(salicylideneiminato)]cobalt(III). The complexes have been assigned octahedral geometry on the basis of analytical and spectral data.

Synthesis and Spectral Characterization of Mixed Ligand Complexes of Co(II), Ni(II), and Cu(II) with 5‐Methyluracil, Amino Acids, and N‐(2‐Acetamido)iminodiacetic Acid

Mixed ligand ternary metal complexes of some divalent transition metal ions [Co(II), Ni(II), and Cu(II)] with 2,4‐dihydroxy‐5‐methylpyrimidine (5‐methyluracil, HL1) and some dicarboxylic amino acids (aspartic and glutamic, H2L2) or basic amino acids (asparagine and glutamine, HL2) as well as N‐(2‐acetamido)iminodiacetic acid as disodium salt (Na2ADA, H2L2) were prepared. The structure of the complexes was characterized by the elemental and thermal analyses, IR, and electronic spectra as well as the conductivity measurements. Six‐coordinated metal complexes were suggested for the various isolated ternary complexes of Co(II), Ni(II), and Cu(II), with molecular formulas dependent on the nature of amino acids or Na2ADA ligands (L2) present.

Electrochemical Study of the Mixed Ligand Complexes of Co(II) and Ni(II) with Acetylsalicylic Acid and Nicotinamide

The interaction of acetylsalicylic acid (aspirin, aspH) and nicotinamide (NA) with Co(II) and Ni(II) ions was investigated using square-wave and cyclic voltammetry techniques. In the presence of Ni(II)/Co(II),nicotinamide gave new peaks at -0.85V and soh.12 V, corresponding to the reduction of Ni(II)-nicotinamide(log β1:2 =5.97) and Co(II)-nicotinamide (log β1:2 =5.19) complexes, respectively. In the presence of Ni(II)/Co(II), acetylsalicylic acid gave new peaks at -0.91V and -1.19 V, respectively, corresponding to the reductionof Ni(II)-salicylate (log β1:2 =8.48) and Co(II)-salicylate (log β1:2 =8.14) complexes. In the presence of nicotinamide, Ni(II)-salicylate and Co(II)-salicylate form mixed ligand complexes, reducing at -0.78V (log β1:2:2 =9.68) and -1.14V (log β1:2:2 =8.64), respectively.

Snythesis, characterization and thermal dissociation of cobalt(II) complexes of the photoproducts of octacyanomolybdate(IV) and -tungstate(IV) with ethylenediamine

Photosubstituted mixed ligand complexes of Co(II) with irradiated solutions of Mo(CN) 8 4− and W(CN) 8 4− with ethylenediamine have been synthesized. The complexes have been isolated and characterized by their elemental analysis and IR spectroscopy. The assigned formulae are Co 2[Mo(CN) 2(C 2H 8N 2) 2(OH) 2]Cl 4.2H 2O I and Co[W(CN) 2(C 2H 8N 2) 2(OH) 2]Cl 2.2H 2O II for Mo(IV) and W(IV) complexes, respectively. The IR peaks observed for both the complexes show N–H stretching, H–N–H bending and stretching vibrations of the C–N and C–C bonds. Depending on the nature of the absorption bands, complex I is assigned as - trans and complex II as - cis configuration. The thermal decomposition of these complexes has been studied by TG and DSC techniques. The reaction scheme for decomposition of each complex has been proposed. The activation energy ( E a), pre-exponential factor ( A) and entropy of activation (Δ S #) have been calculated by employing the integral methods like Arrhenius, Coats–Redfern and Doyle. Enthalpy (Δ H) values for each transition are obtained from DSC data.

Some Biologically Active Mixed Ligand Complexes of Co(II), Cu(II) and Ni(II) with ONO, NNO and SNO Donor Nicotinoylhydrazine-Derived Ligands

Abstract A series of new biologically active mixed ligand complexes of Co(II), Cu(II) and Ni(II) with nicotinoylhydrazine-derived ONO, NNO and SNO Schiff base ligands (L1, L2 and L3) have been synthesised and characterised on the basis of conductance and magnetic measurements, elemental analyses and 1H NMR, IR and electronic spectral data. The synthesised ligands and their complexes have been screened for their antibacterial activity against bacterial species Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The activity data show the metal complexes to be more active than the parent free ligands against one or more bacterial species.

Synthesis and Characterization of M(II) Acetylacetonate-Imidazole Mixed Ligand Complexes

Abstract Mixed ligand complexes of Co(II), Ni(II) and Cu(II) with acetylacetone as a primary ligand and imidazole or substituted imidazole as a secondary ligand were synthesized and characterized by microchemical analyses, conductance, electronic and infrared spectral measurements. It is concluded that the acetylacetonate ligand coordinates to the metal ion as a monovalent bidentate ligand while the imidazole or substituted imidazole coordinates to the metal ion as a monodentate ligand.

Spectral and Thermal Studies on Some New Anionic Mixed Alkyldithiocarbonato-Oxinato Transition Metal Complexes

The preparation and characterization of some anionic mixed ligand com plexes of Co(II), Ni(II) and Cu(II) containing the two anionic ligands alkyldithiocarbonate and oxinate are reported. The ionic nature of the complexes was inferred from the conductivity data. Alkyldithiocarbonates act in these complexes as bidentate ligands. Based on the spectroscopic and magnetic data the complexes appear to possess pseudo-octahedral metal coordination.

Thermal and spectral studies of some mixed ligand complexes of Co(II), Ni(II) and Cu(II) involving aliphatic and heterocyclic β-diketone

Mixed Ligand complexes of the type MLL'· nH 2O, where M = Co(II), Ni(II) or Cu(II), L = acetylacetone, benzoylacetone or dibenzoylmethane and L' = 1-phenyl-3-methyl-4-benzoyl-2-pyrazoline-5-one, have been synthesized by the reactions of two different ligands L and L' in aqueous alcoholic medium. The pyridine adducts of the mixed ligand complexes [MLL'(py) 2] have also been synthesized and all complexes are suitably characterized. Thermal studies of the mixed ligand complexes and their pyridine adducts have been carried out to determine their mode of decomposition, apparent activation energy and the order of each thermal reaction. Infrared and thermogravimetric analyses suggest that two water molecules are present in the coordination sphere of the Co(II) and Ni(II) mixed ligand complexes showing that they are paramagnetic and octahedral in geometry.

Characterisation of Mixed Ligand Complexes of Cobalt(II) and Nickel(II) with Diphenic Acid As Primary and Heterocyclic Bases as Secondary Ligands

Abstract The mixed ligand complexes of Co(II) and Ni(II) with diphenic acid as primary and quinoline, isoquinoline, pyridine, 8-hydroxy quinoline and 2-amino pyridine as secondary ligands were prepared and characterised on the basis of elemental analysis, conductivity measurements, magnetic, infra-red and electronic spectral studies. The complexes of Co(II) with quinoline and pyridine were octahedral, with 8-hydroxy quinoline and 2-amino pyridine were tetrahedral and with isoquinoline was square planar. The NI(II) complexes were octahedral except for that with isoquinoline which was square planar.

Some Structural Aspects of Pyrrolidinate Mixed Ligand Complexes of Co(II), Ni(II) and Cu(II) and their Antifungal Activity

Some Structural Aspects of Pyrrolidinate Mixed Ligand Complexes of Co(II), Ni(II) and Cu(II) and their Antifungal Activity

Some Studies on Mixed Ligand Complexes of Co(II), Ni(II) and Zn(II) with Hydrazine and Oxalic Acid

Some Studies on Mixed Ligand Complexes of Co(II), Ni(II) and Zn(II) with Hydrazine and Oxalic Acid

Mixed Ligand Complexes of Co(II) with Pyrocatechol Violet and Xylenol Orange as Primary and Amino Acids as Secondary Ligands

Mixed Ligand Complexes of Co(II) with Pyrocatechol Violet and Xylenol Orange as Primary and Amino Acids as Secondary Ligands

Chelating Behaviour of A Substituted Pylwzolecarboxylic Acid, A Potential Lisand of Biclogical Interest: Mixed Digand Complexes of Cobalt(II), and Nickel(II) with 1,5-Dimethylpyrazole-3-Carboxylic Acid and Heterocyclic Amines

Abstract Mixed ligand complexes of Co(II) and NI(II) with 1,5-dirhethylprrrezole-3-carboxvlic mid (dmpcH) and heterocyclic amines are reported. Structural characterisation of the complexes M(dmpc)2.B.nH2O [M = CO or Ni, 3 = Pyridine,β - or γ-picoline, ½ o-phenanthroline, ½ bipyridyl, n = 0,2], is made from electronic and vibrational spectra, magnetic susceptibility measurements in the solid state and conductivity measurements in solution. The ‘dmpc’ anion functions as a monoacidic bidentate ligand.

Mixed Ligand Complexes of Co(II), Ni(ll), Cu(ll) and Zn Salts with o-Hydroxy Propiophenone and Quinoline

Mixed Ligand Complexes of Co(II), Ni(ll), Cu(ll) and Zn Salts with o-Hydroxy Propiophenone and Quinoline

Ternary Complexes in Solution: Mixed Ligand Complexes of Co(lI), Ni(ll), Zn(lI), or Cd(lI) with N, S Donor Ligands

Abstract The stability constants of ternary Co(II), Ni(II), Zn(II), or Cd(II) complexes containing 2,2′-bipyridyl (bipy) or 1,10-phenanthroline (phen) as a primary ligand and N-phenyl-2-mercaptopropion-amide (PMP) as a secondary ligand in a 1:1:1 molar ratio were determined using the Irving-Rossotti pH-titration technique in a 70% (v/v) dioxane-water mixture (I=0.1 M NaC104; 30 ± 1°C) in an inert atmosphere. The stability of these ternary complexes is discussed on the basis of π -accepting qualities of the sulfur ligand and the participating heteroaromatic N-base.

New mixed ligand complexes of Co(III) containing ethylenediamine, propylenediamine and some bidentate NN, OO and NO donor ligands

New mixed ligand complexes of Co(III) containing ethylenediamine, propylenediamine and some bidentate NN, OO and NO donor ligands