Spectral,thermal and magnetic investigations of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 4-methylphthalates

Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 4-methylphthalates were investigated and their composition, solubility in water at 295 K and magnetic moments were determined. IR spectra and powder diffraction patterns of the complexes prepared with molar ratio of metal to organic ligand of 1.0:1.0 and general formula: M [ CH₃C₆H₃(CO₂)₂]·nH₂o (n=1-3) were recorded and their decomposition in air were studied. During heating the hydrated complexes are dehydrated in one (Mn, Co, Ni, Zn, Cd) or two steps (Cu) and next the anhydrous complexes decompose to oxides directly (Cu, Zn), with intermediate formation of carbonates (Mn, Cd), oxocarbonates (Ni) or carbonate and free metal (Co). The carboxylate groups in the complexes studied are mono- and bidentate (Co, Ni), bidentate chelating and bridging (Zn) or bidentate chelating (Mn, Cu, Cd). The magnetic moments for paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.92, 5.05, 3.36 and 1.96 M.B., respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis, crystal structure, spectroscopic and photoluminescence studies of manganese(II), cobalt(II), cadmium(II), zinc(II) and copper(II) complexes with a pyrazole derived Schiff base ligand

Varying coordination modes of the Schiff base ligand H₂L [5-methyl-1-H-pyrazole-3-carboxylic acid (1-pyridin-2-yl-ethylidene)-hydrazide] towards different metal centers are reported with the syntheses and characterization of four mononuclear Mn(II), Co(II), Cd(II) and Zn(II) complexes, [Mn(H₂L)(H₂O)₂](ClO₄)₂(MeOH) (1), [Co(H₂L)(NCS)₂] (2), [Cd(H₂L)(H₂O)₂](ClO₄)₂ (3) and [Zn(H₂L)(H₂O)₂](ClO₄)₂ (4), and a binuclear Cu(II) complex, [Cu₂(L)₂](ClO₄)₂ (5). In the complexes 1-4 the neutral ligand serves as a 3N,2O donor where the pyridine ring N, two azomethine N and two carbohydrazine oxygen atoms are coordinatively active, leaving the pyrazole-N atoms inactive. In the case of complex 5, each ligand molecule behaves as a 4N,O donor utilizing the pyridine N, one azomethine N, the nitrogen atom proximal to the azomethine of the remaining pendant arm and one pyrazole-N atom to one metal center and the carbohydrazide oxygen atom to the second metal center. The complexes 1-4 are pentagonal bipyramidal in geometry. In each case, the ligand molecule spans the equatorial plane while the apical positions are occupied by water molecules in 1, 3 and 4 and two N bonded thiocyanate ions in 2. In complex 5, the two Cu(II) centers have almost square pyramidal geometry (τ = 0.05 for Cu1 and 0.013 for Cu2). Four N atoms from a ligand molecule form the basal plane and the carbohydrazide oxygen atom of a second ligand molecule sits in the apex of the square pyramid. All the complexes have been X-ray crystallographically characterized. The Zn(II) and Cd(II) complexes show considerable fluorescence emission while the remaining complexes and the ligand molecule are fluorescent silent.     

New Complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with 3,3-dimethylglutaric Acid

Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)3,3-dimethylglutarates were investigated and their quantitative composition, solubility in water at 293 K and magnetic moments were determined. IR spectra and powder diffraction patterns of the complexes prepared with general formula MC₇H₁₀O₄⋅nH₂O (n=0−2) were recorded and their thermal decomposition in air were studied. During heating the hydrated complexes of Mn(II),Co(II), Ni(II) and Cu(II) are dehydrated in one step and next all the anhydrous complexes decompose to oxides directly (Mn, Co, Zn) or with intermediate formation free metal (Ni,Cu) or oxocarbonates (Cd). The carboxylate groups in the complexes studied are bidentate. The magnetic moments for the paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II)attain values 5.62, 5.25, 2.91 and 1.41 M.B., respectively. This revised version was published online in August 2006 with corrections to the Cover Date.     

Spectral and Thermal Studies of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) Complexes with 3-methylglutaric Acid

Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 3-methylglutarates were prepared as solids with general formula MC₆ H₈ O₄ ×n H₂ O, where n =0–8. Their solubilities in water at 293 K were determined (7.0×10⁻² −4.2×10⁻³ mol dm⁻³ ). The IR spectra were recorded and thermal decomposition in air was investigated. The IR spectra suggest that the carboxylate groups are mono- or bidentate. During heating the hydrated complexes lose some water molecules in one (Mn, Co, Ni, Cu) or two steps (Cd) and then mono- (Cu) or dihydrates (Mn, Co, Ni) decompose to oxides directly (Mn, Cu, Co) or with intermediate formation of free metals (Co, Ni). Anhydrous Zn(II) complex decomposes directly to the oxide ZnO. This revised version was published online in July 2006 with corrections to the Cover Date.     

Kinetics and mechanism of zinc(II), cadmium(II), and mercury(II) incorporation into meso tetrameta-tolueneporphyrin

The kinetics of Zn(II), Cd(II), and Hg(II) incorporation into meso tetrameta-tolueneporphyri n (H₂T(m-CH₃)PP) in acetone have been studied by means of stopped-flow method. A unified reaction mechanism was proposed and the kinetic parameters were obtained by nonlinear least-square methods. The effect of ionic strength (I) on Cd(II)/H₂T(m-CH₃)PP was investigated. It has been found that there is a negative kinetic salt effect and the relationship of rate constants with ionic strength was obtained. Some solvent effects have also been investigated in this article. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 277–283, 1998.     

Synthesis and Characterization of Complexes of Copper(II), Nickel(II) and Cobalt(II) with vic-Dioximes Bearing N''-p-Aminobenzoyl Benzaldehyde Hydrazone

Six different arylhydrazone derivatives of p-aminobenzoic hydrazide of vic-dioximes were synthesized by reaction of chloroglyoxime and dichloroglyoxime with N＇-p-aminobenzoyl benzaldehyde, 4-hydroxybenzaldehyde and 4-methoxybenzaldehyde hydrazones, respectively. Metal-ligand （1 ： 2） complexes of vic-dioxime derivatives with Cu（Ⅱ）, Ni（Ⅱ） and Co（Ⅱ） were prepared from corresponding metal acetates. The ligands and their complexes were characterized on the basis of elemental analyses and spectral data. The complexing abilities of these new vic-dioximes toward transition metals of Co（Ⅱ）, Cu（Ⅱ）, Ni（Ⅱ）, Zn（Ⅱ）, Cd（Ⅱ）, Mn（Ⅱ） and Cr（Ⅲ） were determined by solid-liquid extraction studies.     

Physico-chemical studies of Ni(II), Co(II), Zn(II), and Cd(II) ions with p-fluorobenzoylacetone

Incorporation of pH correction, in data obtained from the potentiometric titration of p-fluorobenzoylacetone with NaOH solution in dioxane-water (31,V/V) at 30±0.1°C in a medium of constant ionic strength, =0.1M (NaClO₄) gave the value of thermodynamic dissociation constant (pk _D ) as 12.06±0.02. Under similar conditions of solvent composition, temperature and ionic strength the thermodynamic stepwise formation constants of the complexes formed between Ni(II), Co(II), Zn(II) and Cd(II) ions and the above ligand, using method of least squares, gave log ₂ as 19.50±0.05, 18.89±0.05, 18.61±0.04 and 16.16±0.08 resp. This order is in accordance with theIrving-Williams series. Derivatives of the above metals have also been synthesised and characterised.With 2 Figures     

Preparation,Properties and Thermal Decompositions of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) Complexes of 2,5-dichlorobenzoic Acid

Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 2,5-dichlorobenzoates were prepared and their compositions and solubilities in water at 295 K were determined. The IR spectra and X-ray diffractograms of the obtained complexes were recorded. The complexes of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) were obtained as solids with a 1:2 molar ratio of metal to organic ligand and different degrees of hydration. When heated at a heating rate of 10 K min^-1, the hydrated complexes lose some (Co, Zn) or all (Ni, Cu, Cd) of the crystallization water molecules and then decompose to oxide MO (Co, Ni) or gaseous products (Cu, Zn, Cd). When heated at a heating rate of 5 K min^-1, the complexes of Ni(II) and Cu(II) lose some (Ni) or all (Cu) of the crystallization water molecules and then decompose directly to MO. This revised version was published online in July 2006 with corrections to the Cover Date.     

Heteronuclear complexes of oxorhenium(V) with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO2(VI) and their biological activities

Heteronuclear complexes containing oxorhenium(V), with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO₂(VI) ions were prepared by the reaction of the complex ligands [ReO(HL¹)(PPh₃)(OH₂)Cl]Cl (a) and/or [ReO(H₂L²)(PPh₃)(OH₂)Cl]Cl (b), where H₂L¹?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(5,6-diphenyl-1,2,4-triazine-3-ylhydrazone) and H₃L²?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(1H-benzimidazol-2-ylhydrazone), with transition and actinide salts. Heterodinuclear complexes of ReO(V) with Fe(III), Co(II), Ni(II), Cu(II) and Cd(II) were obtained using a 1?:?1 mole ratio of the complex ligand and the metal salt. Heterotrinuclear complexes were obtained containing ReO(V) with UO₂(VI) and Cu(II) using 2?:?1 mole ratios of the complex ligand and the metal salts. The complex ligands a and b coordinate with the heterometal ion via a nitrogen of the heterocyclic ring and the nitrogen atom of the C=N⁷ group. All transition metal cations in the heteronuclear complexes have octahedral configurations, while UO₂(VI)?complexes have distorted dodecahedral geometry. The structures of the complexes were elucidated by IR, ESR, electronic and ¹H NMR spectra, magnetic moments, conductance and TG-DSC measurements. The antifungal activities of the complex ligands and their heteronuclear complexes towards Alternaria alternata and Aspergillus niger showed comparable behavior with some well-known antibiotics.     

Synthesis and spectral studies of new macrocyclic Schiff base Cu(II), Ni(II), Cd(II), Zn(II), Pb(II), and La(III) complexes containing pyridine head unit

1,6-Bis(2-formylphenyl) hexane (I) was derived from 1,6-dibromohexane with salicylaldehyde and K₂CO₃ and the ligand (L) was derived from compound I and 2,6-diaminopyridine. Then, the Cu(II), Ni(II), Pb(II), Zn(II), Cd(II), and La(III) complexes with L were synthesized by the reaction of this ligand and Cu(NO₃)₂ · 3H₂O, Ni(NO₃)₂ · 6H₂O, Pb(NO₃)₂, Zn(NO₃)₂ · 6H₂O, Cd(NO₃)₂ · 6H₂O, and La(NO₃)₃ · 6H₂O, respectively. The ligand and its metal complexes were characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV-Vis spectra, magnetic susceptibility, conductivity measurements, and mass spectra. All complexes are diamagnetic and the Cu(II) complex is binuclear. The article is published in the original.     

Potentiometric study of the Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with 3-hydroxy-2-naphthalene carboxylic acid

Formation constants of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with 3-hydroxy-2-naphthalene carboxylic acid have been determined potentiometrically in a 50% (v/v) dioxane—water solution at 25°C and 0.2 M KNO₃. Experimental data are analysed using several computer programs. The obtained values for the log of the formation constant of the first 1 : 1 (metal : ligand) complex with the different metals are: Co 7.9, Ni 7.1, Cu 10.44, Zn 7.8 and Cd 7.3. The log of the formation constant for the 1 : 2 copper complex is 18.20. It is to be noted that Ni(II) yields a 1 : 1 complex weaker than expected from the Irving—Williams series.     

Some peculiarities of metal exchange reactions in porphyrin and phthalocyanine complexes

Kinetics of metal exchange reaction Cd(II) Zn(II) and Cd(II) Cu(II) in Cd complexes with tetraphenylporphyrin in DMSO is studied. Reaction with Cu(II) nitrate occurs in both cases more vigorously as compared to that with Zn(II) nitrate. Conditions for metal exchange reactions are studied depending on the nature of metal porphyrinate, a salt (nitrates, acetates, and chlorides of Zn(II), Cu(II), and Co(II), and of organic solvent (DMSO, CH₃CN). It is shown that Zn(II) complexes with nonplanar porphyrins do not show metal exchange Zn(II) Cu(II) or Zn(II) Co(II) under mild conditions in DMSO and CH₃CN.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 2, 2005, pp. 104–109. Original Russian Text Copyright © 2005 by D. Berezin, Shukhto, Nikolskaya, B. Berezin.     

The thermodynamic characteristics of formation of mono-and binuclear biladiene Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) chelates in dimethylformamide solutions

The spectral and calorimetric data on complex formation between alkyl substituted a,c-biladiene and Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) acetates in dimethylformamide are discussed. The stability of mononuclear biladiene chelates was shown to be determined by steric factors characterizing the formation of coordination polyhedra with the tetradentate ligand. The thermodynamic characteristics of the differential polychelate effect caused by the replacement of the bidentate dipyrrolylmetene ligand with the tetradentate biladiene anion in mononuclear zinc(II) complexes were estimated. The results showed that the largest contribution to the polychelate effect was made by the enthalpy component of the Gibbs energy.     

Spectrothermal studies of 1,10-phenanthroline complexes of Co(II), NI(II), Cu(II) and Cd(II) orotates

The 1,10-phenanthroline (phen) complexes of Co(II), Ni(II), Cu(II) and Cd(II) orotates were synthesized and characterized by elemental analysis, magnetic susceptibility, spectral methods (UV-vis and FTIR) and thermal analysis techniques (TG, DTG and DTA). The Co(II), Ni(II), Cu(II) and Cd(II) ions in diaquabis(1,10-phenanthroline)metal(II) diorotate octahedral complexes [M(H₂O)₂(phen)₂](H₂Or)₂·nH₂O (M=Co(II), n=2.25; Ni(II), n=3; Cu(II) and Cd(II), n=2) are coordinated by two aqua ligands and two moles of phen molecules as chelating ligands through their two nitrogen atoms. The monoanionic orotate behaves as a counter ion in the complexes. On the basis of the first DTG_max, the thermal stability of the hydrated complexes follows the order: Cd(II), 68°C 68°C     

Synthesis and Characterization of Cu(II), Ni(II), Co(II), Mn(II), and Cd(II) Transition Metal Complexes of Tridentate Schiff Base Derived from O-Vanillin and N-Aminopyrimidine-2-Thione

Abstract

Monobasic tridentate Schiff base ligand having ONS donor sequence was prepared by condensing N-aminopyrimidine-2-thione with o-vanillin. The complexes were formed by reacting ligand and the metal acetates of Cu(II), Ni(II), Co(II), Mn(II), and Cd(II) in methanol to get a series of mononuclear and dinuclear complexes. The characterization of ligand and metal complexes were carried out by elemental analyses, conductivity measurements, magnetic susceptibility data, FTIR, UV-vis, NMR, and API-ES mass spectral data. The structure of the complexes was confirmed on the basis of elemental analyses, magnetic susceptibility, API-ES mass spectral data and thermal gravitational analysis (TGA).

GRAPHICAL ABSTRACT      

Thermal Behaviour of the N-donor Adducts of Metal Saccharinates. II. 1,10-phenanthroline saccharinato complexes of Co(II), Ni(II), Cu(II), Zn(II) and Pb(II)

Adducts of Co(II), Ni(II), Cu(II), Zn(II) and Pb(II) saccharinates with 1,10-phenathroline were synthesized and their thermoanalytical (TG, DTG and DTA) curves in the 20–1000°C temperature interval and static air atmosphere were recorded. The complexes are best represented as M(C₁₂H₈N₂)_x(C₇H₄NO₃S)₂⋅yH₂O (x=2, 2, 2, 2 and 1; y=1, 1, 2, 1 and 2 for M=Co, Ni, Cu, Zn and Pb, respectively). The decomposition of the compounds regularly started with dehydration, followed by loss of the phenanthroline ligand(s). The structures of the Cu and Pb complexes are notably different from other compounds. FTIR spectra of the title compounds in the region of the OH, CO and SO₂ stretching vibrations were also studied. The pronounced similarity of the spectra of Co, Ni and Zn adducts indicates possible isomorphism among them. This revised version was published online in July 2006 with corrections to the Cover Date.     

Complexes of Co(II), Ni(II) and Cu(II) with lapachol

Complexes of naturally occurring hydroxynaphtho-quinone, lapachol (2-hydroxy-3(3-methyl-2-buthenyl)-1,4-naphthoquinone = HL) with Co(II), Ni(II) and Cu(II) have been prepared by reaction of the corresponding acetates with the ligand (HL) in ethanol. The molecular and crystal structures were determined for [CoL₂(EtOH)₂] (1), [NiL₂(EtOH)₂] (2), and [CuL₂(py)₂] (3). In all cases the deprotonated lapachol behaves as chelating bidentate ligand. The complexes were also characterized by elemental analyses, cyclic voltammetry, and FAB-MS.     

Synthesis,spectral characterization,and antimicrobial activity of copper(II), cobalt(II), and nickel(II) complexes of 3-formylchromoniminopropylsilatrane

A new series of Cu(II), Ni(II), and Co(II) complexes have been synthesized from 3-formylchromoniminopropylsilatrane (C₁₉H₂₄O₅N₂Si) (2) and 3-formylchromoniminopropyltriethoxysilane (1). Silatrane ligand (C₁₉H₂₄O₅N₂Si) (2) has been synthesized by the reaction between 3-aminopropyltriethoxysilane and 3-formylchromone followed by a treatment with triethanolamine. The nature of bonding and the geometry of the complexes have been deduced from elemental analyses, magnetic susceptibility, infrared, electronic, ¹H NMR, ¹³C NMR, and ESR spectral studies. The electronic absorption spectra and magnetic susceptibility measurements of the complexes indicate square planar geometry for Cu(II) and Ni(II) and tetrahedral geometry for Co(II). The redox behavior of copper complexes was studied by cyclic voltammetry. The biological activity of the ligand and metal complexes has been studied on Klebsiella pneumoniae, Staphylococcus aureus, Escherichia Coli, and Bacillus subtilis by the well diffusion method using acetonitrile as solvent. The zone of inhibition values were measured at 37°C for 24 h. Antimicrobial screening tests show better results for the metal complexes than the ligand.     

Synthesis, Characterization and Biological Evaluation of Fe (III), Co (II), Ni(II), Cu(II), and Zn(II) Complexes with Tetradentate Schiff Base Ligand Derived from Protocatechualdehyde with 2-Aminophenol

Schiff base ligand (H₃L) was prepared from the condensation reaction of protochatechualdehyde (3,4-dihydroxybenzaldhyde)with 2-amino phenol. From the direct reaction of the ligand (H₃L) with Co(II), Ni(II) and Cu(II) chlorides, and Fe(III)and Zn(II)nitrates in 2?M/1?L molar ratio, the five new neutral complexes were prepared. The characterization of the newly formed compounds was done by ¹H NMR, UV?CVis, and IR spectroscopy and elemental analysis. The in vitro antibacterial activity of the metal complexes was studied and compared with that of free ligand.     

Ternary complexes in solution: Complex formation between copper(II), zinc(II), cadmium(II) and ligands of biological importance

The stability constants of ternary complexes of theMAL type have been determined for Cu(II), Zn(II) and Cd(II). The ligands chosen for this study belong to the biologically important ones viz. Bipyridyl (A) and Nitrilotriacetic acid (L). LogK _MAL values for Cu(II), Zn(II) and Cd(II) are 11.42, 10.67 and 9.72, respectively, at temp.=25°C and =0.1M (KNO₃); the order is discussed.

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Ternäre Komplexe in Lösung: Die Komplexibildung zwischen Kupfer(II), Zink(II) und Kadmium(II) mit Liganden von biologischem Interesse

Zusammenfassung Die Stabilitätskonstanten für Cu(II)-, Zn(II)- und Cd(II)-Komplexe vom TypMAL wurden bestimmt. Die biologisch relevanten Liganden, die für diese Untersuchung ausgewählt wurden, waren Bipyridyl (A) und Nitrilotriessigsäure (L). Bei einer Temperatur von 25°C und =0,1M (KNO₃) sind die entsprechenden logK _MAL -Werte für Cu(II), Zn(II) und Cd(II) 11,42, 10,67 und 9,72; diese Reihenfolge wird ebenfalls diskutiert.