Synthesis and photoluminescent properties of a Schiff-base ligand and its mononuclear Zn(II), Cd(II), Cu(II), Ni(II) and Pd(II) metal complexes

Mononuclear Zn(II), Cd(II), Cu(II), Ni(II) and Pd(II) metal complexes of Schiff-base ligand(HL₁) derived from 8-acetyl-7-hydroxycoumarin and P-phenylenediamine were prepared and characterized by microanalytical, mass, UV–Vis, IR, ¹H NMR, ¹³C NMR, ESR, conductance and fluorescence studies. The measured low molar conductance values in DMSO indicate that the complexes are non-electrolytes. The structures of the solid complexes under study are established by using IR, electronic and ESR spectroscopy suggesting that Zn(II) and Ni(II) complexes are octahedral, Cd(II) complex is tetrahedral, Cu(II) and Pd(II) complexes are square planar. The ESR spectrum of the Cu(II) complex in DMSO at 298 and 150 K was recorded and its salient features are reported, it supports the mononuclear structure. The Schiff base exhibited photoluminescence originating from intraligand (π–π*) transitions. Metal-mediated enhancement is observed on complexation of HL with Zn(II) and Cd(II), whereas metal-mediated fluorescence quenching occurs in Cu(II), Ni(II) and Pd(II).     

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).     

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.     

Template synthesis and physicochemical studies of 14-membered hexaazmacrocyclic complexes with Co(II), Ni(II), Cu(II) and Zn(II): a comparative spectroscopic approach on DNA binding with Cu(II) and Ni(II) complexes

A new series of 14-membered pendant arm hexaazamacrocyclic complexes of the type [MLX₂] · [M = Co(II), Ni(II), Cu(II) or Zn(II) for X = Cl; Co(II), Ni(II), Cu(II) or Zn(II) for X = NO₃] has been synthesized by metal template condensation of 1,2-phenylenediamine and 1,4-phenylenediamine with formaldehyde in methanol. The mode of bonding and overall geometry of these complexes have been deduced by elemental analyses, molar conductance values, FT-IR, ¹H-NMR, ¹³C-NMR, EPR, ESI-mass and UV–VIS along with magnetic measurement studies. The fluorescence and UV–VIS studies revealed a significant binding ability to DNA.     

Coordination Behavior of N‐Donor Schiff Base Derived from 2‐Benzoylpyridine Toward Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), and Cr(III) Metal Ions: Synthesis,Spectroscopic and Thermal Studies,and Biological Activity

A new Schiff base was prepared from the reaction of 4,4′‐methylenedianiline with 2‐benzoylpyridine in 1:2 molar ratio, as well as its different metal chelates. The structures of the ligand and its metal complexes were studied by elemental analyses, spectroscopic methods (infrared [IR ], ultraviolet–visible [UV –vis], ¹H nuclear magnetic resonance [NMR ], electron spin resonance [ESR ]), magnetic moment measurements, and thermal studies. The ligand acts as tetradentate moiety in all complexes. Octahedral geometry was suggested for Mn(II ), Cu(II ), Cr(III ), and Zn(II ) chloride complexes and pentacoordinated structure and square planar geometry for Co(II ), Ni(II ), Cu(NO₃ )₂, CuBr₂ , and Pd(II ) complexes. ESR spectra of copper(II ) complexes ( 4 )–( 6 ) at room temperature display rhombic symmetry for complex ( 4 ) and axial type symmetry for complexes ( 5 ) and ( 6 ), indicating ground state for Cu(II ) complexes. The derivative thermogravimetric (DTG ) curves of the ligand and its metal complexes were analyzed by using the rate equation to calculate the thermodynamic and kinetic parameters, which indicated strong binding of the ligand with the metal ion in some complexes. Also, some of these compounds were screened to establish their potential as anticancer agents against the human hepatic cell line Hep‐G₂ . The obtained IC₅₀ value of the copper(II ) bromide complex (4.34 µg/mL ) is the highest among the compounds studied.     

Spectroscopic and Molecular Docking Studies of Cu(II), Ni(II), Co(II), and Mn(II) Complexes with Anticonvulsant Therapeutic Agent Gabapentin

New Cu(II), Ni(II), Co(II), and Mn(II) complexes of the gabapentin (Gpn) bidentate drug ligand were synthesized and studied using elemental analyses, melting temperatures, molar conductivity, UV–Vis, magnetic measurements, FTIR, and surface morphology (scanning (SEM) and transmission (TEM) electron microscopes).The gabapentin ligand was shown to form monobasic metal:ligand (1:1) stoichiometry complexes with the metal ions Cu(II), Ni(II), Co(II), and Mn(II). Molar conductance measurements in dimethyl-sulfoxide solvent with a concentration of 10⁻³ M correlated to a non-electrolytic character for all of the produced complexes. A deformed octahedral environment was proposed for all metal complexes. Through the nitrogen atom of the –NH₂ group and the oxygen atom of the carboxylate group, the Gpn drug chelated as a bidentate ligand toward the Mn²⁺, Co²⁺, Ni²⁺, and Cu²⁺ metal ions. This coordination behavior was validated by spectroscopic, magnetic, and electronic spectra using the formulas of the [M(Gpn)(H₂O)₃(Cl)]·nH₂O complexes (where n = 2–6).Transmission electron microscopy was used to examine the nanostructure of the produced gabapentin complexes. Molecular docking was utilized to investigate the comparative interaction between the Gpn drug and its four metal [Cu(II), Ni(II), Co(II), and Mn(II)] complexes as ligands using serotonin (6BQH) and dopamine (6CM4) receptors. AutoDock Vina results were further refined through molecular dynamics simulation, and molecular processes for receptor–ligand interactions were also studied. The B3LYP level of theory and LanL2DZ basis set was used for DFT (density functional theory) studies. The optimized geometries, along with the MEP map and HOMO → LUMO of the metal complexes, were studied.     

Synthesis,characterization and fluorescence spectra of mixed ligand Zn(II), Cd(II) and Hg(II) complexes with 1,10-phenanthroline-5,6-dione ligand

The novel mixed ligand complexes [M(bpy)(phen-dione)](PF₆)₂ (M?=?Zn(II), Cd(II) and Hg(II), bpy?=?2,2^′-bipyridine and phen-dione?=?1,10-phenanthroline-5,6-dione) have been synthesized and characterized by elemental analysis, IR, ¹H NMR and electronic absorption spectroscopies. The ν(C=O) of coordinated phen-dione in these complexes are very similar to the free phen-dione ligand showing that phen-dione is not coordinated to metal ion from its C=O sites. Absorption spectra of the complexes show two absorption bands for intraligand transitions. These absorption bands show dependence to the dielectric constant of solvent. These complexes exhibit an intensive fluorescence band around 535?nm in DMF when the excitation wavelength is 260?nm at room temperature. The fluorescence intensity of these complexes is larger than that of the free ligand.     

Studies of Some New Aminocyclodiphosphazane Complexes of Co(II), Ni(II), and Cu(II)

The ligand aminocyclodiphosph(V)azane derivative (III) and its complexes with Co(II), Ni(II), and Cu(II) ions were prepared and characterized by microanalytical, FTIR, ¹H, ¹³C, and ³¹P-NMR, UV/Visible, thermogravimetric (TGA) analysis, and magnetic moments. The ligand acts in a tetrahedral manner forming 2:1 metal to ligand ratio. The copper complex is assigned to be tetrahedral while cobalt and nickel complexes were assigned to be octahedral structure.     

Preparation of Schiff’s base complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) and their spectroscopic, magnetic, thermal, and antifungal studies

The potassium salt of salicylidene-DL-alanine (KHL), bis(benzylidene)ethylenediamine (A¹), thiophene-o-carboxaldene-p-toluidine (A²), and its metal complexes of the formula [(M^II(L)(A)(H₂O)] (M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II); A = A¹ or A²) are prepared. They are characterized by elemental analysis, magnetic susceptibility measurements, thermogravimetric analysis, and infrared and electronic spectral studies. The electronic spectral and magnetic moment data suggest an octahedral geometry for the complexes. All of these complexes, metal nitrates, fungicides (bavistin and emcarb), and ligands are screened for their antifungal activity against Aspergillus niger, Fusarium oxysporum, and Aspergillus flavus using a plate poison technique. The complexes show higher activity than those of the free ligands, metal nitrate, and the control (DMSO) and moderate activity against bavistin and emcarb. The text was submitted by the authors in English.     

A new pyrimidine-derived ligand,N-pyrimidine oxalamic acid,and its Cu(II), Co(II), Mn(II), Ni(II), Zn(II), Cd(II), and Pd(II) complexes: synthesis,characterization, electrochemical properties,and biological activity

A new heterocyclic compound N-(5-benzoyl-2-oxo-4-phenyl-2H-pyrimidin-1-yl)-oxalamic acid has been synthesized from N-amino pyrimidine-2-one and oxalylchloride. Bis-chelate complexes of the ligand were prepared from acetate/chloride salts of Cu(II), Co(II), Mn(II), Ni(II), Zn(II), Cd(II), and Pd(II) in methanol. The structures of the ligand and its metal complexes were characterized by microanalyses, IR, AAS, NMR, API-ES, UV-Vis spectroscopy, magnetic susceptibility, and thermogravimetric analyses. An octahedral geometry has been suggested for all the complexes, except for Pd(II) complex, in which the metal center is square planar. Each ligand binds using C(2)=O, HN, and carboxylate. The cyclic voltammograms of the ligand and the complexes are also discussed. The new synthesized compounds were evaluated for antimicrobial activities against Gram-positive, Gram-negative bacteria and fungi using the microdilution procedure. The Cu(II) complex displayed selective and effective antibacterial activity against one Gram-positive spore-forming bacterium (Bacillus cereus ATCC 7064), two Gram-positive bacteria (Staphylococcus aureus ATCC 6538 and S. aureus ATCC 25923) at 40–80 µg mL^?1, but poor activity against Candida species. The Cu(II) complex might be a new antibacterial agent against Gram-positive bacteria.     

Ligational behaviour of lomefloxacin drug towards Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO(2)(VI) ions: synthesis, structural characterization and biological activity studies

Nine new mononuclear Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO₂(VI) complexes of lomefloxacin drug were synthesized. The structures of these complexes were elucidated by elemental analyses, IR, XRD, UV–vis, ¹H NMR as well as conductivity and magnetic susceptibility measurements and thermal analyses. The dissociation constants of lomefloxacin and stability constants of its binary complexes have been determined spectrophotometrically in aqueous solution at 25 ± 1 °C and at 0.1 M KNO₃ ionic strength. The discussion of the outcome data of the prepared complexes indicate that the lomefloxacin ligand behaves as a neutral bidentate ligand through OO coordination sites and coordinated to the metal ions via the carbonyl oxygen and protonated carboxylic oxygen with 1:1 (metal:ligand) stoichiometry for all complexes. The molar conductance measurements proved that the complexes are electrolytes. The powder XRD study reflects the crystalline nature for the investigated ligand and its complexes except Mn(II), Zn(II) and UO₂(II). The geometrical structures of these complexes are found to be octahedral. The thermal behaviour of these chelates is studied where the hydrated complexes lose water molecules of hydration in the first steps followed by decomposition of the anions, coordinated water and ligand molecules in the subsequent steps. The activation thermodynamic parameters are calculated using Coats–Redfern and Horowitz–Metzger methods. A comparative study of the inhibition zones of the ligand and its metal complexes indicates that metal complexes exhibit higher antibacterial effect against one or more bacterial species than the free LFX ligand. The antifungal and anticancer activities were also tested. The antifungal effect of almost metal complexes is higher than the free ligand. LFX, [Co(LFX)(H₂O)₄]·Cl₂ and [Zn(LFX)(H₂O)₄]·Cl₂ were found to be very active with IC50 values 14, 11.2 and 43.1, respectively. While, other complexes had been found to be inactive at lower concentration than 100 μg/ml.     

Synthesis and spectroscopic,magnetic and cyclic voltammetric characterization of some metal complexes of methionine: [(C5H10NO2S)2MII]; MII = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II)

Some metal complexes of DL–methionine were prepared in aqueous medium and characterized by different physico-chemical methods. Methionine forms 1:2 complexes with metal, M(II). The general empirical formula of the complexes is proposed as [(C₅H₁₀NO₂S)₂M^II]; where M^II = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II). All the complexes are extremely stable in light and air and optically inactive. Magnetic susceptibility data of the complexes demonstrate that they are high spin paramagnetic complex except Zn(II), Cd(II) and Hg(II) complexes. The bonding pattern in the complexes are similar to each other as indicated by electronic absorption spectra and FTIR spectral analysis. The current potential data, peak separation (AE) and the peak current ratio (i_pa/i_pc) of the (Mn, Cu and Cd) complexes indicate that the charge transfer processes are irreversible, the systems are diffusion controlled and also adsorptive controlled. The charge transfer rate constant of metals in their complexes are less than those in their metal salts at identical experimental conditions due to the coordination of metal with methionine.     

Complexation en solution aqueuse des ions magnesium(II), manganese(II), nickel(II), cuivre(II) et plomb(II) avec la s-carboxymethyl-l-cysteine: Complex formation of magnesium(II), manganese(II), nickel(II), copper(II) and lead(II) with S-carboxymethyl-L-cysteine in aqueous solution

Complex formation of magnesium(II), manganese(II), nickel(II), copper(II) and lead(II) with S-carboxymethyl-L-cysteine in aqueous solution.The complex formation between Mg(II), Mn(II), Ni(II). Cu(II), Pb(II) ions and S-carboxy-methyl-l-cysteine (H₂A) has been studied by measurement of pH at 25°C and constant ionic strength (1 M NaClO₄). Although no interaction occurs with Mg(II), this work provides evidence for a variety of complexes: MnA; CuHA⁺; CuA; CuA₂^2-; NiHA⁺; NiA; NiA₂^2-; PbHA⁺; PbA et PbA(OH)^-. The overall formation constants of all these species are computed and refined. The results allow the determination of the distribution of the complexes as a function of pH; some structural features of the metal complexes in solution are indicated.     

Synthetic,spectroscopic, fluorescence,and biological investigation of Co(II), Ni(II), Cu(II), and Zn(II) complexes of Schiff bases derived from 3-formyl-2-mercaptoquinolines (Quinol-2-thiones)

Co(II), Ni(II), Cu(II), and Zn(II) complexes have been prepared with Schiff bases derived from 3-formyl-2-mercaptoquinoline and substituted anilines. The prepared Schiff bases and chelates have been characterized by elemental analysis, molar conductance, magnetic susceptibilities, electronic, IR, ¹H-NMR, ESR, cyclic voltammetry, FAB-mass, and thermal studies. The complexes have stoichiometry of the type ML₂ · 2H₂O coordinating through azomethine nitrogen and thiolate sulfur of 2-mercapto quinoline. An enhancement in fluorescence has been noticed in the Zn(II) complexes whereas quenching occurred in the other complexes. The ligands and their metal complexes have been screened in vitro for antibacterial and antifungal activities by MIC methods with biological activity increasing on complexation. Cu(II) complexes show greater bacterial than fungicidal activities. The brine shrimp bioassay was also carried out to study the in vitro cytotoxicity properties of the ligands and their corresponding complexes. Only four compounds have exhibited potent cytotoxic activity against Artemia salina; the other compounds were almost inactive for this assay.     

Amberlite XAD-7 impregnated with Xylenol Orange: a chelating collector for preconcentration of Cd(II), Co(II), Cu(II), Ni(II), Zn(II) and Fe(III) ions prior to their determination by flame AAS

A new chelating resin, Xylenol Orange coated Amberlite XAD-7, was prepared and used for preconcentration of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) prior to their determination by flame atomic absorption spectrophotometry. The optimum pH values for quantitative sorption of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) are 4.5–5.0, 4.5, 4.0–5.0, 4.0, 5.0 and 5.0–7.0, respectively, and their desorptions by 2 mol L^–1 HCl are instantaneous. The sorption capacity of the resin has been found to be 2.0, 2.6, 1.6, 1.6, 2.6 and 1.8 mg g^–1 of resin for Cd, Co, Cu, Fe, Ni and Zn, respectively. The tolerance limits of electrolytes, NaCl, NaF, NaI, NaNO₃, Na₂SO₄ and of cations, Mg²⁺ and Ca²⁺ in the sorption of the six metal ions are reported. The preconcentration factor was between 50 and 200. The t_1/2 values for sorption are found to be 5.3, 2.9, 3.2, 3.3, 2.5 and 2.6 min for the six metals, respectively. The recoveries are between 96.0 and 100.0% for the different metals at preconcentration limits between 10 to 40 ng mL^–1. The preconcentration method has been applied to determine the six metal ions in river water samples after destroying the organic matter (if present in very large amount) with concentrated nitric acid (RSD ≤ 8%, except for Cd for which it is upto 12.6%) and cobalt content of vitamin tablets with RSD of ～ 3.0%.     

Structural studies on cadmium(II), cobalt(II), copper(II), nickel(II) and zinc(II) complexes of 1-malonyl-bis(4-phenylthiosemicarbazide)

Summary Several new complexes of the title ligand (H₂MPTS) with Co^II, Ni^II, Cu^II, and Cd^II have been prepared. Structural assignments of the complexes have been made based on elemental analysis, molar conductivity, magnetic moment and spectral (i.r.,¹H n.m.r., reflectance) studies. The compounds are non-conductors in dimethylsulphoxide. The neutral molecule is coordinated to the metal(II) sulphate as a bidentate ligandvia the two carbonyl groups. The ligand reacts with the metal(II) chlorides with the liberation of two hydrogen ions, behaving as a bianionic quadridentate (NONO) donor. Enolization is confirmed by the pH-titration of H₂ MPTS and its metal(II) complexes against NaOH. A distorted octahedral structure is proposed for the Cu^II complex, while a square planar structure is suggested for both Co^II and Ni^II complexes. The stoichiometry of the complexes formed in EtOH and buffer solutions, their apparent formation constants and the ranges for obedience to Beer's law are reported for Co^II, Ni^II and Cu^II ions. The ligand pK values are calculated. The antimicrobial activity of H₂ MPTS and its Co^II, Ni^II, Cu^II and Mn^II complexes is demonstrated.     

Polymetallic complexes: Part VI. Schiff base complexes of cobalt(II), copper(II), nickel(II), zinc(II), cadmium(II) and mercury(II)

Summary The doubly bidentate ON-NO donor Schiff base, prepared from salicylaldehyde and 4,4-diaminodiphenylmethane forms complexes with 11 metal: ligand stoichiometric ratios. The cobalt(II), copper(II) and nickel(II) complexes exhibit subnormal magnetic moments. All the six complexes possess high melting points and are sparingly soluble in common organic solvents. A dinuclear octahedral structure is proposed for the cobalt(II), copper(II), nickel(II) and zinc(II) complexes and a dinuclear tetrahedral configuration is suggested for the cadmium(II) and mercury(II) complexes on the basis of analytical, conductance, magnetic susceptibility, molecular weight, i.r. and electronic spectral data.     

Synthesis,characterization and fluorescence spectra of mononuclear Zn(II), Cd(II) and Hg(II) complexes with 1,10-phenanthroline-5,6-dione ligand

The mononuclear complexes of Zn(II), Cd(II) and Hg(II), [Zn(phen-dione)Cl₂], [Cd(phen-dione)Cl₂] and [Hg(phen-dione)Cl₂], where phen-dione?=?1,10-phenanthroline-5,6-dione, have been synthesized and characterized by elemental analysis and IR, ¹H?NMR and electronic absorption spectroscopies. The ν(C=O) of coordinated phen-dione ligands in these complexes shows that the phen-dione is not coordinated to metal ion from its C=O sites. Electronic spectra of the complexes show two absorption bands for intraligand transitions. These absorption bands show dependence on the dielectric constant of solvents. These complexes exhibit an intense fluorescence band around 545?nm in DMSO when the excitation wavelengths are 200?nm at room temperature.     

New zinc(II), copper(II), nickel(II), and vanadium(IV) complexes containing disulfide ligand: Synthesis,spectroscopic studies and calf thymus DNA interaction investigation

New Schiff base complexes of zinc(II), copper(II), nickel(II), and vanadium(IV) were synthesized using the Schiff base ligand formed by the condensation of 2-aminoethanethiol and 2-hydroxy-1-naphthaldehyde. The tetradentate Schiff base ligand N,N´-(3,4-dithiahexane-1,6-diyl)bis(2-hydroxy-1-naphthaleneimine), containing a disulfide bond, was coordinated to the metal(II) ions through the two azomethine nitrogen atoms and two deprotonated phenolic oxygens of two different ligands which was connected to each other by sulfur-sulfur bond. The molar conductivity values of complexes in DMSO solvent implied the presence of nonelectrolyte species. The fluorescence properties of the Schiff base ligand and its complexes were studied in dimethylsulfoxide. The Schiff base ligand and its complexes were characterized by FT-IR, ¹H NMR, UV/Vis spectroscopies, elemental analysis, and conductometry. The crystal structure of tetradentate Schiff base ligand was characterized by single crystal X-ray diffraction. The Schiff base ligand was contained disulfide bond. Furthermore, the binding interaction of these complexes with calf thymus DNA (CT-DNA) was investigated by different methods.     

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.