Synthesis and characterization of N,N-diethylnicotinamide-acetylsalicylato complexes of Co(II), Ni(II), Cu(II), and Zn(II)

N,N-diethylnicotinamide-acetylsalicylato complexes of Co(II), Ni(II), Cu(II), and Zn(II) were synthesized and investigated by elemental analysis, magnetic susceptibility, solid state UV–Vis, direct injection probe mass spectra, FTIR spectra and thermoanalytic TG-DTG methods. The complexes contain two waters, two acetylsalicylate (asa) and two N,N-diethylnicotinamide (dena) ligands per formula unit. The acetylsalicylate and N,N-diethylnicotinamide are monodentate through acidic oxygen and nitrogen of pyridine ring. Decomposition of each complex starts with dehydration then decomposition of N,N-diethylnicotinamide and acetylsalicylate, respectively. The thermal dehydration of the complexes takes place in one or two steps. The decomposition mechanism and thermal stability of the investigated complexes are interpreted in terms of their structures. The final decomposition products are found to be metal oxides.     

Synthesis, thermal and other studies of 2,4'-bipyridine-dichloroacetato complexes of Mn(II), Co(II), Ni(II) and Cu(II)

Four new mixed ligand complexes were prepared by the reaction of title metal dichloroacetates and 2,4'-bipyridine. The general formulae of synthesized compounds are M(2,4'-bpy)₂(CCl₂HCOO)₂·nH₂O (where M(II)=Mn, Co, Ni, Cu; 2,4'-bpy=2,4'-bipyridine, n=2 or 4). The complexes have been isolated from aqueous media and characterized by chemical analysis, molar conductance (in MeOH, DMSO and DMF), magnetic, IR and VIS spectral studies. The nature of metal(II)-ligand coordination is discussed. The thermal behaviour of obtained complexes was studied by thermal analysis and TG-MS techniques in air. IR, X-ray powder diffraction and thermoanalytical data were used for the determination of solid intermediate products of the thermal decomposition. The principal volatile products of thermal decomposition of complexes were proved by mass spectroscopy: H₂O⁺, CO⁺ ₂, HCl⁺ ₂, Cl⁺ ₂, NO⁺ and other. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and characterization of bis(nicotinamide) m-hydroxybenzoate complexes of Co(II), Ni(II), Cu(II), and Zn(II)

Mixed-ligand m-hydroxybenzoate complexes of Co(II), Ni(II), Cu(II), and Zn(II) with nicotinamide were synthesized and characterized by elemental analysis, FT-IR spectrometry, solid state UV-vis spectrometry, and magnetic susceptibility measurements. The thermal behavior of the complexes was studied by simultaneous TG-DTA methods in static air atmosphere. The infrared spectral characteristics of the complexes are discussed and the mass spectra data are recorded. The complexes contain two water molecules, two m-hydroxybenzoato (m-hba), and two nicotinamide (na) ligands per formula unit. In these complexes, the m-hydroxybenzoate and nicotinamide behave as a monodentate ligand through acidic oxygen and nitrogen of the pyridine ring. The decomposition pathways and the stability of the complexes are interpreted in terms of the structural data. The final decomposition products were found to be the respective metal oxides. The text was submitted by the author in English.     

Synthesis and characterization of Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes with N-salicydene-o-hydroxymethyleneaniline

The new Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes with tridentate Schiff base, the product of condensation of o-aminobenzyl alcohol with salicylaldehyde have been synthesized and characterized by elemental analysis, IR, electronic, EPR and Mössbauer spectra, thermal analysis, magnetic susceptibility and molecular weight measurements. Dimeric or polymeric structures for the investigated complexes were proposed. The interaction of the cobalt complex with dioxygen is also described.     

Synthesis,characterization and biological studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with pyrral-l-histidinate

The Schiff base ligand, pyrral-l-histidinate(L) and its Co(II), Ni(II), Cu(II) and Zn(II) complexes were synthesized and characterized by elemental analysis, mass, molar conductance, IR, electronic, magnetic measurements, EPR, redox properties, thermal studies, XRD and SEM. Conductance measurements indicate that the above complexes are 1:1 electrolytes. IR data show that the ligand is tridentate and the binding sites are azomethine nitrogen, imidazole nitrogen and carboxylato oxygen atoms. Electronic spectral and magnetic measurements indicate tetrahedral geometry for Co(II) and octahedral geometry for Ni(II) and Cu(II) complexes, respectively. The observed anisotropic g values indicate the presence of Cu(II) in a tetragonally distorted octahedral environment. The redox properties of the ligand and its complexes have been investigated by cyclic voltammetry. Thermal decomposition profiles are consistent with the proposed formulations. The powder XRD and SEM studies show that all the complexes are nanocrystalline. The in vitro biological screening effects of the synthesized compounds were tested against the bacterial species, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus; fungal species, Aspergillus niger, Aspergillus flavus and Candida albicans by the disc diffusion method. The results indicate that complexes exhibit more activity than the ligand. The nuclease activity of the ligand and its complexes were assayed on CT DNA using gel electrophoresis in the presence and absence of H₂O₂.     

Synthesis, characterization and thermal behavior of 1,1-dialkyl-3-(4-(3,3-dialkylthioureidocarbonyl)-benzoyl)thiourea and its Cu(II), Ni(II), and Co(II) complexes

We report the synthesis, characterization, and thermal behavior of 1,1-diethyl-3-(4-(3,3-diethylthioureidocarbonyl)benzoyl)thiourea, 1,1-di-n-propyl-3-(4-(3,3-di-n-propylthioureido carbonyl)benzoyl)thiourea and 1,1-di-n-butyl-3-(4-(3,3-di-n-butylthioureidocarbonyl)benzoyl)thiourea and their Ni(II), Cu(II), and Co(II) complexes. The structure of the prepared compounds was determined by elemental analysis, FT-IR, ¹H NMR spectroscopy and mass spectrometry. The ligands are coordinated to metal atoms in a bidentate manner yielding an essentially neutral complex of the type M₃L₃. Thermal decomposition of related compounds was investigated by DTA and TG techniques. The pyrolytic end product was identified by X-ray powder diffraction method. The text was submitted by the authors in English.     

Spectroscopic and theoretical study of Cu(II), Zn(II), Ni(II), Co(II) and Cd(II) complexes of glyoxilic acid oxime

The paper presents a detailed experimental and theoretical study of five metal complexes of glyoxilic acid oxime (gaoH2), Cu(gaoH)2(H2O)2 (1), Zn(gaoH)2(H2O)2 (2), Co(gaoH)2(H2O)2 (3), Ni(gaoH)2(H2O)2 (4) and [Cd(gaoH)2(H2O)2].H2O (5). The electronic and vibrational spectra were measured and discussed as to the most sensitive to the M-L binding bands. Two different types of coordination were considered for gaoH- ligand: bidentate through the carboxylic oxygen and oxime nitrogen in 1-4 and mixed bidentate and bridging through the COO group in 5. It is shown that the spectral behavior of the nu(COO) modes can be used to predict bridging ligand coordination. DFT(B3LYP/6-31++G(d,p)) calculations on model compounds: neutral, anionic and radical forms of gao and Cu(gaoH)2, have been carried out to correlate geometries, electronic and vibrational structures. The results obtained were used to assist the electronic and vibrational analysis of the complexes studied. The effect of the metal-ligand interactions (electrostatic and covalent) on the geometry structure of the ligand was investigated.     

Synthesis and characterization of oxazolone complexes with Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) in different counterions

Oxazolone forms (1:1) complexes with Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ chlorides, as well as forms (1:1) complexes with Co²⁺ and Cu²⁺ acetates. All the complexes are found to be non-electrolytes in DMF; tetrahedral, square-planar and octahedral structures are assigned to them based on electronic and magnetic data. IR studies reveal that the complexes are formed by donating the lone-pair electron from O and N atoms to the metal ion. The thermal decomposition of the [ML·mX·nH₂O]_y·H₂O chelates was studied by TG–DTA techniques. The mechanism of the decomposition has been established from TG–DTA data. The kinetic parameters, activation energy (E_a) and pre-exponential factor (A), were calculated from TG curves using Coats and Redfern method. Relative thermal stabilities of the chelates have been evaluated on the basis of these parameters.     

Synthesis, characterization and thermal behavior of 4-chloromethyl-2-(2-hydroxybenzilidenehydrazino) thiazole and its complexes with Cr(III), Co(II), Ni(II) and Cu(II)

A new ligand, 4-chloromethyl-2-(2-hydroxybenzilidenehydrazino) thiazole, has been synthesized from dicholoroacetone and 2-hydroxybenzylidenethiosemicarbazon. Metal complexes of the ligand were prepared from acetate salts of Co(II), Cu(II), Ni(II) and chloride of Cr(III) in dry acetone. Characterization of the ligand and its complexes was made by microanalyses, FT-IR, 13C, 1H NMR and UV-vis spectroscopy, magnetic susceptibility and thermogravimetric analysis. In the light of these results, it was suggested that two ligands coordinate to each metal atom by hydroxyl oxygen, imino nitrogen and thiazole ring nitrogen to form high spin octahedral complexes with Cr(III), Co(II), Ni(II) and Cu(II).     

Synthesis and spectroscopic studies of Mn(II), Co(II), and Cu(II) complexes of novel 2-[2,4-Dioxo-4-(thiophen-2-yl)butanamido]benzoic acid ligands

Mn(II), Co(II), and Cu(II) complexes with novel heterocyclic ligands derived from anthranilic acid and its 5-bromo derivative with ethyl-2-thionylpyruvate were synthesized and characterized by means of elemental analysis, molar conductivity, spectral methods (IR, ¹H NMR, and UV-Vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. The IR spectra of the two ligands and their complexes were used to identify the type of bonding. The kinetic thermodynamic parameters such as: E*, ΔH*, ΔS*, and ΔG* were estimated from the DTG curves. New ligands and their complexes have been tested for their possible antibacterial and antifungal activity.     

Synthesis and characterization of heterocyclic Schiff base and its complexes with Cu(II), Ni(II), Co(II), Zn(II), and Cd(II)

A new Schiff base, {1-[(2-hydroxy-naphthalen-1-ylmethylene)-amino]-4-phenyl-2-thioxo-1, 2-dihydro-pyrimidin-5-yl}-phenyl-methanone, has been synthesized from N-amino pyrimidine-2-thione and 2-hydroxynaphthaldehyde. Metal complexes of the Schiff base were prepared from acetate/chloride salts of Cu(II), Co(II), Ni(II), Zn(II), and Cd(II) in methanol. The chemical structures of the Schiff-base ligand and its metal complexes were confirmed by elemental analyses, IR, ¹³C-NMR, ¹H-NMR, API-ES, UV-Visible spectroscopy, magnetic susceptibility, and thermogravimetric analyses. The electronic spectral data and magnetic moment measurements suggest mononuclear octahedral and mononuclear or binuclear square planar structures for the metal complexes. In light of these results, it was suggested that this ligand coordinates to each metal atom by hydroxyl oxygen, azomethine nitrogen, and thione sulfur to form octahedral complexes with Cd(II) and Zn(II).     

Synthesis and thermal behaviour of 4,4′-bipyridyl and 2,4′bipyridyl complexes of Co(II), Ni(II) and Cu(II) thiocyanates

The synthesis and characterization of CoL₂(NCS)₂·2H₂O, NiL₂(NCS)₂·2H₂O, CuL(NCS)₂· 3H₂O (L=4,4′-bipyridyl, 4-bipy) CoX₃(NCS)₂·H₂O, NiX₃(NCS)₂ and CuX₂(NCS)₂ (X=2,4′- bipyridyl, 2,4′-bipy) are reported. The IR spectra and other physical properties of these compounds are discussed. The thermal properties of the complexes in the solid state were studied under non-isothermal conditions in air atmosphere. The intermediates of dehydration and decomposition at different temperatures were characterized by X-ray diffraction.     

Mn(II), Co(II), Ni(II) and Cu(II) complexes of a tertraaza macrocyclic ligand: Synthesis, characterization and biological screening

Manganese(II), cobalt(II), nickel(II) and copper(II) complexes with 1,5,11,15-tetraaza-21,22-dioxo-tricyclo [19,3,1,I^6,10]-5,10,15-20-dicosatetraene (L), as a new macrocyclicligand, have been synthesized with and characterized by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, IR, electronic and EPR spectral studies. The molar conductance measurements of the complexes in DMF correspond to non-electrolytic nature of Mn(II), Co(II) and Cu(II) complexes, while showing a 1:2 electrolyte for thew Ni(II) complexe. Thus, these complexes may be formulated as [M(L)X₂] and [Ni(L)]X₂ (where M = Mn(II), Co(II) and Cu(II) and X = Cl^- and NO₃ ^-). On the basis of IR, electronic and EPR spectral studies, an octahedral geometry has been assigned for Mn(II) and Co(II), a square planar for Ni(II) and tetragonal for Cu(II) complexes. In vitro ligand and its metal complexes were also screened against the growth of some fungal and bacterial species in order to assess their antimicrobial properties.     

Synthesis of coordination compounds of 6-ethoxycarbonyl-3,5-diphenylcyclohex-2-en-1-one with Cu(II), Ni(II), and Co(II)

Russian Journal of General Chemistry -     

Synthesis,characterization and biological properties of Co(II), Ni(II), Cu(II) and Zn(II) complexes with an SNO functionalized ligand

Some new metal(II) complexes, ML₂[M = Co, Ni, Cu and Zn], of 2-acetylthiophene benzoylhydrazone ligand (HL) containing a trifunctional SNO-donor system have been synthesized and characterized on the basis of physicochemical data by elemental analysis, magnetic moment, molar conductance, thermogravimetric and spectroscopic (electronic, IR, ¹H NMR and ¹³C NMR) data. The ligand functions as monobasic SNO tridentates where the deprotonated enolic form is preferred in the coordination producing distorted octahedral complexes.     

Synthesis and Thermal Decomposition of Mixed 2,4'-bipyridine-oxalato Complexes With Mn(II), Co(II), Ni(II) and Cu(II)

The mixed 2,4'-bipyridine-oxalato complexes of the formulae M(2,4'-bipy)₂ C₂ O₄ 2H₂ O (M (II)=Mn, Co, Ni, Cu; 2,4'-bipyridine=2,4'-bipy or L ; C₂ O^2– ₄ =ox) have been prepared and characterized. IR data show that the 2,4'-bipy coordinated with these metals(II) via the least hindered (4')N atom; that oxalate group acts as bidentate chelating ligand. Room temperature magnetic moments are normal for the orbital singlet states. The thermal decomposition of these complexes was investigated by TG, DTA and DTG in air. The endothermic or exothermic character of the decomposition of ML₂ (ox)2H₂ O was discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and Study of Co(II), Ni(II), and Cu(II) Ethylenediaminetetraacetatohydroxogermanates

New heterometallic Ge(IV) and Co(II), Ni(II), and Cu(II) complexonates based on ethylenediaminetetraacetic acid (H₄Edta) were synthesized. The composition of the complexes was determined using elemental analysis and thermogravimetry. Comparison of the IR spectra of [Ge(OH)(HEdta)] ? H₂O, which was structurally characterized previously, with those of the new complexes provided information on the composition and structure of their inner and outer spheres. The cobalt and nickel coordination polyhedra were identified by analyzing the diffuse reflection spectra and the effective magnetic moments and that of copper was identified by EPR.     

Synthesis,spectral characterization,electrochemical and biological studies of Co(II), Ni(II) and Cu(II) complexes with thiocarbohydrazone

A series of metal complexes of Co(II), Ni(II) and Cu(II) have been synthesized with the Schiff base derived from thiocarbohydrazide and 8-formyl-7-hydroxy-4-methylcoumarin. The structures of the complexes have been proposed by elemental analyses, molar conductance, spectral (IR, UV-Vis, ESR and FAB-mass), magnetic, thermal and electrochemical studies. These complexes are soluble in DMF and DMSO and molar conductance values indicate that they are non-electrolytes. Elemental analyses of the complexes confirm stoichiometry ML ·; 2H₂O [M=Co(II), Ni(II) and Cu(II)]. Spectroscopic studies indicate coordination occurs through phenolic oxygen after deprotonation and nitrogen of azomethine. The Schiff base and its complexes have also been screened for antibacterial (Escherichia coli, Streptococcus aureus, Streptococcus pyogenes and Pseudomonas aeruginosa) and antifungal activities (Aspergillus niger, Aspergillus flavus and cladosporium) by the MIC method. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties.