Unsymmetrical Tetradentate Schiff Base Ligands Research Articles

Synthesis and characterization of Co (II), Ni (II) and Cu (II) complexes with unsymmetrical tetradentate Schiff base ligand

A novel series of cobalt (II), nickel (II) and copper (II) complexes of unsymmetrical Schiff base ligand 1-(2-hydroxynaphthalideneimino)-2-(5 methoxysalicylidene imino)-4 chlorobenzene-1,2-diamine was synthesised by condensation reaction of 1:1:1 molar ratio of 2-hydroxynaphthalene-1-carbaldehyde, 4-chlorobenzene -1,2-diamine and 5-methoxysalicyidehyde in alcoholic medium. The synthesised ligand and its metal complexes were characterised by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, UV-Vis and infrared spectral data. The molar conductance of synthesised metal complexes in DMSO solution indicates their non-electrolytic nature. The analytical data show the general formula for the complexes to be [M(L)2] where L = Schiff base ligand and M = Co (II), Ni (II) and Cu (II). The spectral data and magnetic moment suggested that Schiff base behaves as a tetradentate ligand, coordinating through azomethine nitrogen and phenolic oxygen atoms to the metal ion. Magnetic susceptibility measurements, UV-Vis and infrared spectral data geometry of metal complexes were proposed to be square planar.

Oxovanadium and copper complexes of new unsymmetrically tetradentate ligands: X- ray structure, theoretical and NLO properties, catalytic oxidation and bromoperoxidase activities

A series of mononuclear oxovanadium VOLBz, VOLT and copper CuLBz, CuLT complexes containing unsymmetrical tetradentate Schiff base ligands were synthesized and fully characterized by conventional spectroscopic techniques such as FT-IR, UV–vis, 1HNMR and mass spectrometry (MS). Crystal structure data of CuLT, solved by X-ray diffraction, shows a monoclinic system with Cc space group and Z = 4 molecules per unit cell. The central copper ion adopts a nearly ideal square planar coordination geometry. Cyclic voltammetry of oxovanadium and copper complexes revealed quasi reversible redox couples corresponding to VOIV/VOV and CuI/CuII redox processes, respectively. The quantum calculations, performed by DFT and TD-DFT theory at the M062X/6-311**G/SDD level, agree well with the experimental data. The results show that the copper and the oxovanadium compounds have larger static and dynamic hyperpolarizability values than the urea. For instance, the β0 value of H2LT is about 68 times larger than that of the urea. The results predict that the studied compounds have the ability to be excellent second and third-order NLO materials. The prepared complexes catalyzed effectively homogeneous oxidation reaction of cyclohexene in the presence of H2O2 as oxidant. Higher conversion of 98% is attained using CuLBz as catalyst. The bromoperoxidase activity is explored in the oxidative bromination of phenol red as a trap employing the studied complexes which can be considered as potential functional models of bromoperoxidase, CuLBz catalyst exhibits the better catalytic activity, the reaction rate constant k is equal to 2.203×105 (mol L-1)-2s-1.

Spectroscopic investigation, molecular structure, catalytic activity with computational studies of a novel Pd(II) complex incorporating unsymmetrical tetradentate Schiff base ligand

The treatment of an unsymmetrical tetradentate Schiff base ligand with Pd(OAc)2 salt yields novel palladium(II) Schiff base complex. The generated palladium(II) complex was characterized using elemental analysis (CHN) and different spectroscopic methods such as FT-IR and 1H NMR. Single crystal X-ray diffraction (SC-XRD) investigation has also been used to examine the crystal structure of the palladium complex. It is revealed from the SC-XRD study that the palladium ion in the complex is tetra-coordinated, inhabited by ONNO donor sites of the chelated ligand in a distorted square planar manner. The non-covalent interactions were explored by Hirshfeld surface analysis. The theoretical parameters calculated by DFT using the B3LYP/Def2-TZVP level of theory revealed that the theoretical conclusions matched the actual findings. For different aryl halides, the palladium(II) complex has exhibited excellent efficiency in the Suzuki-Miyaura cross-coupling reactions (SMCR), yielding biaryls in good to high yield.

Synthesis, Characterization, and In Vitro Cytotoxicity of Unsymmetrical Tetradentate Schiff Base Cu(II) and Fe(III) Complexes.

Unsymmetrical tetradentate Schiff base Fe(III) and Cu(II) complexes were prepared by the coordination of some unsymmetrical tetradentate Schiff base ligands with CuCl2·2H2O or FeCl3·6H2O. The obtained complexes were characterized by ESI-MS, IR, and UV-Vis. The spectroscopic data with typical signals are in agreement with the suggested molecular formulae of the complexes. Their cyclic voltammetric studies in acetonitrile solutions showed that the Cu(II)/Cu(I) and Fe(III)/Fe(II) reduction processes are at (−)1.882–(−) 1.782 V and at (−) 1.317–(−) 1.164 V, respectively. The in vitro cytotoxicity of obtained complexes was screened for KB and Hep-G2 human cancer cell lines. The results showed that almost unsymmetrical tetradentate Schiff base complexes have good cytotoxicity. The synthetic complexes bearing the unsymmetrical tetradentate Schiff base ligands with different substituted groups in the salicyl ring indicate different cytotoxicity. The obtained Fe(III) complexes are more cytotoxic than Cu(II) complexes and relative unsymmetric Schiff base ligands.

Syntheses, structures and electrochemical properties of ruthenium(II/III) complexes with tetradentate Schiff base ligands

Three unsymmetrical tetradentate Schiff base ligands, H2salipn, H2salipn-Br4 and H2salipn-Cl2, have been synthesized from the typical condensation reactions of treating 1,2-diaminopropane with salicylaldehyde, 3,5-dibromosalicylaldehyde and 5-chlorosalicylaldehyde, respectively. Treatment of [RuCl2(PPh3)3] with one equivalent of H2salipn or H2salipn-Br4 in the presence of triethylamine in tetrahydrofuran (THF) afforded the corresponding ruthenium(III) complexes [RuIIICl(PPh3)(salipn)] (1) and [RuIIICl(PPh3)(salipn-Br4)] (2). Interaction of [RuHCl(CO)(PPh3)3] with one equivalent of H2salipn-Cl2 or H2salipn-Br4 under the same conditions led to isolation of ruthenium(II) complexes [RuII(CO)(PPh3)(salalipn-Cl2)] (3) and [RuII(CO)(PPh3)(salalipn-Br4)] (4), respectively, in which one of the imine bonds was nucleophilically attacked by hydride to result in the formation of a mixed imine-amine ligand. The molecular structures of 1⋅1.5CH2Cl2, 2, 3⋅0.5CH2Cl2 and 4 have been determined by single-crystal X-ray crystallography. The electrochemical properties of 1–4 were also investigated. Their cyclic voltammograms displayed quasi-reversible Ru(IV)/Ru(III) and Ru(III)/Ru(II) couples with Eo ranging from 0.67 to 1.05 V and 0.74 to 0.80 V vs. Ag/AgCl (0.1 M), respectively.

Cobalt (II) complex with novel unsymmetrical tetradentate Schiff base (ON) ligand: in vitro cytotoxicity studies of complex, interaction with DNA/protein, molecular docking studies, and antibacterial activity

[C20H17N3O2] and cobalt (II) complex [Co(L2)(MeOH)2].ClO4, (L2 = 4-((E)-1-((2-(((E)-pyridin-2-ylmethylene) amino) phenyl) imino) ethyl) benzene-1, 3-diol) novel Schiff base has been synthesiszed and chracterized by Fourier transform infrared, UV–vis, 1H-NMR spectroscopy, and elemental analysis techniques. The interaction of Co(II) complex with DNA and BSA was investigated by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroism, and thermal denaturation studies. Our experiments indicate that this complex could strongly bind to CT-DNA via minor groove mechanism. In addition, fluorescence spectrometry of BSA with the complex showed that the fluorescence quenching mechanism of BSA was of static type. The complex exhibited significant in vitro cytotoxicity against three human cancer cell lines (JURKAT, SKOV3, and U87). The molecular docking experiment effectively proved the binding of complex to DNA and BSA. Finally, antibacterial assay over gram-positive and gram-negative pathogenic bacterial strains was studied.

Synthesis, Characterization, Spectral Studies, Antibacterial Evaluation, Thermodynamics and DFT Calculations of Dimethyltin(IV) Dichloride Schiff Base.

A number of new 1:1 complexes of SnMe(2)Cl(2) with unsymmetrical tetradentate Schiff base ligand with NNOS coordination sphere have been synthesized and fully characterized by a variety of physico-chemical techniques viz. elemental analysis, molar conductivity, (1)H and (119)Sn NMR, IR and mass spectroscopy. IR spectral data show that the fifth coordination position of tin atom is occupied by an oxygen atom of Schiff base ligands. In the light of titled techniques, trigonal bipyramidal geometry around the tin atom is proposed for the synthesized complexes. The in vitro antibacterial activities of the complexes against Staphylococcus aureus and Escherichia Coli have been studied. It was found that they possess significant antibacterial activity. Also, DFT/B3LYP method was used to analyze the electronic structures and study of the geometries. The thermodynamic formation constants of the complexes were determined spectrophotometrically at 25ºC in DMF solvent.

Synthesis, characterization, electrical and catalytic studies of some coordination compounds derived from unsymmetrical Schiff base ligand

New unsymmetrical tetradentate Schiff base ligand derived from 5-chloro-2-hydroxyacetophenone, 2-hydroxy-5-methyl-3-nitro acetophenone and carbohydrazide and its complexes with VO(IV), Cr(III), Mn(III), Fe(III), MoO2(VI), WO2(VI), Zr(IV) and UO2(VI) have been prepared. They were characterized by elemental analysis, IR and electronic spectra, magnetic susceptibility measurements and thermal analyses. The Schiff base ligand has also been characterised by 1H-NMR spectroscopy. The thermal behaviour of metal complexes shows that the hydrated complexes lose water molecules of hydration in the first and then is immediately followed by decomposition of ligand molecule in the subsequent steps. The IR spectra suggest that ligand acts as dibasic tetradentate nature and coordination takes place through azomethine nitrogen and phenolate oxygen. The crystalline nature of the VO(IV) complex was conformed through the powder XRD analysis. The catalytic activity of the VO(IV) and Mn(III) complexes have been tested in the epoxidation reaction of styrene and conversion of styrene were 11.14-24.35% and 9.64-23.42%, respectively. The solid state electrical conductivity of ligand and its complexes were measured, which could obeyed the relation s = s0 exp (Ea/KT) over the temperature range 313-413 K. KEY WORDS: Schiff base, Metal complexes, TGA, Electrical conductivity, XRD, Oxidation of styrene Bull. Chem. Soc. Ethiop. 2015, 29(3), 387-397. DOI: http://dx.doi.org/10.4314/bcse.v29i3.6

Template synthesis, and X-ray crystal structures of copper(II) and nickel(II) complexes of new unsymmetrical tetradentate Schiff base ligands. Electrochemistry, antibacterial properties, and metal ion effect on hydrolysis–recondensation of the ligand

Two metal complexes, [CuII(naphsal)] (1), and [NiII(salnaph)] (2), of two new unsymmetrical tetradentate Schiff base ligands, H2naphsal {H2naphsal=N-naphthylidene-N′-salicylidene-2-aminobenzylamine} and H2salnaph {H2salnaph=N-salicylidene-N′-naphthylidene-2-aminobenzylamine} have been synthesized by metal template reaction of a tridentate Schiff base, Hnaphtabza {Hnaphtabza=N-(naphthylidene)-2-aminobenzylamine} and salicylaldehyde in the presence of the corresponding metal acetate. The dianionic naphsal2− ligand, produced in the presence of Cu(II), is a simple template condensation product, while the dianionic salnaph2− ligand, produced in the presence of Ni(II), is the hydrolytically rearranged isomer of naphsal2−. The copper(II) and nickel(II) complexes have been fully characterized and their crystal structures have been determined by single crystal X-ray diffraction. Both copper(II) and nickel(II) ions adopt a distorted square planar geometry. The cyclic voltammetric studies of 1 and 2 in acetonitrile solution showed that the CuII/CuI and NiII/NiI reduction processes are electrochemically reversible. The metal complexes were also screened for their in vitro antimicrobial activity.

Synthesis, crystal structure, and electrochemical properties of Ni(II) and Cu(II) complexes with two unsymmetrical N2O2 Schiff base ligands

Nickel(II) and copper(II) complexes of two unsymmetrical tetradentate Schiff base ligands [Ni(Me-salabza)] (1), [Cu(Me-salabza)] (2) and [Ni(salabza)] (3), {H2salabza = N,N′-bis[(salicylidene)-2-aminobenzylamine] and H2Me-salabza = N,N′-bis[(methylsalicylidene)-2-aminobenzylamine]}, have been synthesized and characterized by elemental analysis and spectroscopic methods. The crystal structures of 2 and 3 complexes have been determined by single crystal X-ray diffraction. Both copper(II) and nickel(II) ions adopt a distorted square planar geometry in [Cu(Me-salabza)] and [Ni(salabza)] complexes. The cyclic voltammetric studies of these complexes in dichloromethane indicate the electronic effects of the methyl groups on redox potential.

Synthetic, characterization and catalytic studies of some coordination compounds derived from unsymmetrical quadridentate Schiff base ligand

The stable complexes of VO(IV), Cr(III), Mn(III), Fe(III), MoO2(VI), and WO2(VI), with an unsymmetrical tetradentate Schiff base ligand derived from 2-hydroxy-5-methylacetophenone, 2-hydroxy-5-chloroacetophenone and carbohydrazide were synthesized and characterized by the elemental analysis, UV-Vis and IR spectroscopy, magnetic measurements and thermal analysis. The VO(IV) and Mn(III) complexes were tested for the catalytic oxidation of styrene. The conversion of styrene increases with use of VO(IV) catalyst and decreases with use of Mn(III) catalyst.

Synthesis, spectroscopic characterization, and 3D molecular modeling of lead(II) complexes of unsymmetrical tetradentate Schiff-base ligands

Solid complexes of Pb(II) with unsymmetrical Schiff-base ligands (H2L) derived from 2-aminobenzophenone, thiosemicarbazide, semicarbazide, salicylaldehyde, 2-hydroxynaphthaldehyde, and o-hydroxyacetophenone have been synthesized and characterized by elemental analysis, conductance measurements, molecular weight measurement, and UV–Vis, FTIR, 1H NMR, and 13C NMR spectroscopy. The spectral studies suggest the ligands behave as dibasic tetradentate ligands with ONNO/ONNS donor atom sequences toward the central metal ion. From the microanalytical data, the stoichiometry of the complexes was found to be 1:1 (metal:ligand). The physicochemical data suggest a tetracoordinated environment around the metal ion. Three-dimensional molecular modeling and analysis of bond lengths and bond angles have also been conducted for a representative compound, [PbL1], to substantiate the proposed structures.

Synthesis, structure and electrochemistry of Co(III) complexes with an unsymmetrical Schiff base ligand derived from 2-aminobenzylamine and pyrrole-2-carboxaldehyde

A series of cobalt(III) complexes with a new unsymmetrical tetradentate Schiff base ligand N,N’-bis(pyrrol-2-ylmethylene)-2-aminobenzylamine, H 2pyrabza, formed by the condensation of 2-pyrrole carboxaldehyde and 2-aminobenzylamine, has been synthesized and characterized by elemental analyses, IR, UV–Vis and 1H NMR spectroscopy. These complexes have the general formula trans-[Co III(L)(amine) 2]X {L 2− = pyrabza, and amine = N-methylimidazole (N-MeIm) ( 1), 3-methylpyridine (3-Mepy) ( 2), 4-methylpyridine (4-Mepy) ( 3), pyridine (py) ( 4), X = BPh 4 - }. The structure of compound 1 has been determined by X-ray crystallography. The geometry around the central cobalt ion is distorted octahedral. The electrochemical behavior of these complexes was also investigated. The reduction potential of Co(III), ranging from −0.79 V for 1 to −0.44 V for 4, shows a relatively good correlation with the σ-donor ability of the axial ligands.

Synthesis and characterization of nickel(II) and copper(II) complexes with tetradentate Schiff base ligands

The 1:1 condensation of 1,2-diaminopropane and 1-phenylbutane-1,3-dione at high dilution gives a mixture of two positional isomers of terdentate mono-condensed Schiff bases 6-amino-3-methyl-1-phenyl-4-aza-2-hepten-1-one (HAMPAH) and 6-amino-3,5-dimethyl-1-phenyl-4-aza-2-hexen-1-one (HADPAH). The mixture of the terdentate ligands has been used for further condensation with pyridine-2-carboxaldehyde or 2-acetylpyridine to obtain the unsymmetrical tetradentate Schiff base ligands. The tetradentate Schiff bases are then allowed to react with the methanol solution of copper(II) and nickel(II) perchlorate separately. The X-ray diffraction confirms the structures of two of the complexes and shows that the condensation site of the diamine with 1-phenylbutane-1,3-dione is the same.

Isolation of a novel intermediate during unsymmetrical to symmetrical rearrangement of a tetradentate Schiff base ligand in a manganese(III) complex: Catalytic activity of the rearranged product towards alkene epoxidation

An attempt for the synthesis of a Mn III complex with unsymmetrical tetradentate Schiff base ligand uspen (1:1:1 condensate of salicylaldehyde, 2,4-pentanedione and 1,2-ethanediamine) resulted in the isolation of a novel complex, {[{Mn(salen)}{Mn(uspen)}(HCOO)]·ClO 4} n ( 1) as an intermediate species that contains both the unsymmetrical and symmetrical tetradentate ligand uspen and salen (2:1 condensate of salicylaldehyde and 1,2-ethanediamine) respectively. The structure of the complex shows that half of the unsymmetrical Schiff base, uspen rearranged to its symmetrical analogue, salen. A phenoxo bridged dinuclear Mn III complex [Mn(salen)(sal)] 2·2H 2O ( 2) with only the symmetrical Schiff base was also obtained. Compound 1 that contains both unsymmetrical and symmetrical Schiff base ligands in one molecule is unprecedented and provides an insight into the unsymmetrical to symmetrical rearrangement of tetradentate Schiff base ligand. Complex 2 acts as an efficient catalyst in the alkene (( E)-stilbene, styrene) epoxidation reaction in presence of two terminal oxidants PhIO and NaOCl in solvents CH 3CN and CH 2Cl 2 independently and it retains its reactivity with high efficiency for a long time.

Nickel (II) and Copper (II) Complexes Derived from NNOS Donor Unsymmetrical Tetradentate Schiff Base Ligands: Synthesis, Characterization, and Thermodynamic Studies

A set of eight unsymmetrical tetradentate Schiff bases (cdPhsalpd = Methyl-2-{[3-(2-hydroxyphenyl)phenylidynenitrilo]propyl}amino-1-cyclopentenedithiocarboxylate; cd3-, 4-, 5-OMesalpd = Methyl-2-{[3-(2-hydroxy 3-, 4-, 5-methoxyphenyl)methylidynenitrilo]propyl} amino-1-cyclopentenedithiocarboxylate; cd5Clsalen = Methyl-2-{[3-(2-hydroxy-5-chloro phenyl)methylidynenitrilo]propyl}amino-1-cyclopentenedithiocarboxylate; cd5Brsalen = Methyl-2-{[3-(2-hydroxy-5-bromophenyl)methylidynenitrilo]propyl}amino- 1-cyclopente- nedithiocarboxylate; cd5NO2salen = Methyl-2-{[3-(2-hydroxy-5-nitrophenyl)methylidyne- nitrilo]propyl}amino-1-cyclopentenedithiocarboxylate; and cd5SO3Na = Methyl-2-{[3- (2-hydroxy-5-sodiumsulfitephenyl)methylidynenitrilo]propyl} amino-1-cyclopentenedithi- ocarboxylate, have been obtained by condensation of methyl-2-(3-aminopropylamino) cyclopentenedithiocarboxylate (Hcdpd) with some substituted salicylaldehydes, 2-hydroxy acetophenone, and 2-hydroxy benzophenone, which present a NNOS coordination spheres. Also, the metal complexes (M = Cu, Ni) of these ligands were prepared and characterized by elemental analysis, IR, 1H NMR, UV-Vis, and mass spectrometry.The formation constants and the thermodynamic free energies were measured using UV-Vis spectrophotometry titration for 1:1 complex formation at constant ionic strength 0.1 M (NaClO4) at 25°C in DMF. The trend of the complex formation of the nickel and copper complexes is as follows: [M(cdMesalpd)] > [(Mcdsalpd)] > [M(cdPhsalpd)] and [M(cd5OMesalpd)] > [M(cd3OMesalpd)] > [M(cd4OMesalpd)] and [M(cd5OMesalpd)] > [M(cdsalpd)] > [M(cd5Brsalpd)] > [M(cd5Clsalpd)] > [M(cd5SO3Nasalpd)] > [M(cd5NO2salpd)]. Our results revealed the thermodynamic formation constant, K f, and the free energy values for Cu(II) complexes are higher than the Ni(II) complexes. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Two highly unsymmetrical tetradentate (N 3O) Schiff base copper(II) complexes: Template synthesis, structural characterization, magnetic and computational studies

Two new copper(II) complexes, [Cu 2(L 1) 2](ClO 4) 2 ( 1) and [Cu(L 2)(ClO 4)] ( 2), of the highly unsymmetrical tetradentate (N 3O) Schiff base ligands HL 1 and HL 2 (where HL 1 = N-(2-hydroxyacetophenone)-bis-3-aminopropylamine and HL 2 = N-(salicyldehydine)-bis-3-aminopropylamine) have been synthesised using a template method. Their single crystal X-ray structures show that in complex 1 two independent copper(II) centers are doubly bridged through phenoxo-O atoms (O1A and O1B) of the two ligands and each copper atom is five-coordinated with a distorted square pyramidal geometry. The asymmetric unit of complex 2 consists of two crystallographically independent N-(salicylidene)-bis(aminopropyl)amine-copper(II) molecules, A and B, with similar square pyramidal geometries. Cryomagnetic susceptibility measurements (5–300 K) on complex 1 reveal a distinct antiferromagnetic interaction with J = −23.6 cm −1, which is substantiated by a DFT calculation ( J = −27.6 cm −1) using the B3LYP functional. Complex 1, immobilized over highly ordered hexagonal mesoporous silica, shows moderate catalytic activity for the epoxidation of cyclohexene and styrene in the presence of TBHP as an oxidant.

Synthesis, spectroscopic characterization and antibacterial activity of new cobalt(II) complexes of unsymmetrical tetradentate (OSN 2) Schiff base ligands

Cobalt ion complexes with the Schiff bases, (4-X-2-{[2-(2-pyridine-2-yl-ethylsulfanyl)ethylimino]methyl}phenol (X = methoxy (OMe), phenylazo (N 2Ph), bromo (Br), nitro (NO 2)),were synthesized and investigated by several techniques using elemental analysis (C, H, N), FTIR, electronic spectra and molar conductivity. The thermal stability of free ligands and related cobalt complexes were studied by using differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). Cyclic voltammetry indicates that the investigated cobalt complexes, under the experimental conditions, have irreversible redox behavior. The synthesized compounds have antibacterial activity against the four Gram-positive bacteria: Streptococcus pyogenes, Streptococcus agalactiae, Staphylococcus aureus and Bacillus anthracis and also against the two Gram-negative bacteria: Klebsiella pneumoniae and Pseudomonas aeruginosa. The activity data show that the parent Schiff bases are more potent antibacterials than the cobalt complexes.

5-{2-[(2-Hydroxy-5-methylphenyl)(phenyl)methyleneamino]phenyliminomethyl}pyrrole-2-carbaldehyde

The title compound, C26H21N3O2, is an unsymmetrical tetra­dentate Schiff base ligand. The hydr­oxy group forms an intra­molecular O—H⋯N hydrogen bond with an adjacent N atom. An inter­molecular N—H⋯O hydrogen bond creates centrosymmetric dimers in the crystal packing.

Synthesis, characterization and the thermodynamic studies of some unsymmetrical tetradentate Schiff-base ligands and their Ni(II) and Cu(II) complexes

Some new unsymmetrical tetradentate Schiff-base ligands, (N-salicylidene-N′-pyrrolidene)-1,2-ethylenediamine(H2salpyren) (H2L1), (H2Mesalpyren) (H2L2), (H2phsalpyren) (H2L3), (N-salicylidene-N′-pyrrolidene)-1,3-propylenediamine (H2salpyrpd) (H2L4), (H2Mesalpyrpd) (H2L5), (H2phsalpyrpd) (H2L6) and their Ni(II) and Cu(II) complexes were synthesized and characterized by elemental analyses, IR, UV-Vis, 1H NMR and mass spectra and magnetic moments. Possible structures of these complexes have been proposed. The thermodynamic formation constants of the complexes were determined spectrophotometrically at constant ionic strength 0.1 M (NaClO4), at 25°C in methanol.