Complexes of Co(II), Ni(II), and Cu(II) with 4-(3,4-dichlorophenyl)-1,2,4-triazole

Novel oligonuclear complexes of Co(II), Ni(II), and Cu(II) with 4-(3,4-dichlorophenyl)-1,2,4-triazole (L) of the composition [M₃L₁₀(H₂O)₂](NO₃)₆ (M = Co(II), Ni(II)), [Ni₃L₆(H₂O)₆]Hal₆ (Hal = Cl^?, Br^?), and [Cu₅L₁₆(H₂O)₂](NO₃)₁₀ · 2H₂O were synthesized and studied by magnetic susceptibility, electronic and IR spectroscopy, and powder X-ray diffraction methods. All the above complexes are X-ray amorphous. Antifer-romagnetic exchange interactions between the M²⁺ ions were discovered in the [Co₃L₁₀(H₂O)₂](NO₃)₆ and [Ni₃L₁₀(H₂O)₂](NO₃)₆ complexes, whereas ferromagnetic exchange interactions were observed in the complexes [Ni₃L₆(H₂O)₆]Cl₆, [Ni₃L₆(H₂O)₆]Br₆, and [Cu₅L₁₆(H₂O)₂](NO₃)₁₀ · 2H₂O.     

Supramolecular networks with 1-substituted benzotriazole ligands and transition metals

1-(2-Pyridyl)benzotriazole (L1) and 1-(4-pyridyl)benzotriazole (L2) with transition metal cations Co(II), Ni(II) and Cu(II) give four coordination complexes, [{Cu(L1)₂(H₂O)₂} · 2NO₃] (1), [{Co(L1)₂(H₂O)₂} · 2NO₃] (2), [Ni(L2)₂(NO₃)₂(H₂O)₂] (3), and [Cu₂(L2)₂(CH₃COO)₄] (4). In 1–4, different supramolecular frameworks are formed through hydrogen bonding and/or π–π interactions.     

Synthesis and characterization of new macrocyclic Schiff base derived from 2,6-diaminopyridine and 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane and its Cu(II), Ni(II), Pb(II), Co(III) and La(III) complexes

A new macrocyclic ligand, 1,3,5-triaza-2,4:7,8:16,17-tribenzo-9,12,15-trioxacyclooktadeca-1,5-dien (L) was synthesized by reaction of 2,6-diaminopyridine and 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane. Then, its Cu(II), Ni(II), Pb(II), Co(III) and La(III) complexes were synthesized by template effect by reaction of 2,6-diaminopyridine and 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane and Cu(NO₃)₂ · 3H₂O, Ni(NO₃)₂ · 6H₂O, Pb(NO₃)₂, Co(NO₃)₂ · 6H₂O, La(NO₃)₃ · 6H₂O, respectively. The ligand and its metal complexes have been characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV–Vis spectra, magnetic susceptibility, thermal gravimetric analysis, conductivity measurements, mass spectra and cyclic voltammetry. All complexes are diamagnetic and Cu(II) complex is binuclear. The Co(II) was oxidized to Co(III). The comparative electrochemical studies show that the nickel complex exhibited a quasi-reversible one-electron reduction process while copper and cobalt complexes gave irreversible reduction processes in DMSO solution.     

Synthesis,characterization and biological activity of triaminoxime and its metal complexes

Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes of multifunctional triaminoxime have been synthesized and characterized by elemental analyses, IR, UV–Vis spectra, magnetic moments, ¹H- and ¹³C-NMR spectra for ligand and its Ni(II) complex, mass spectra, molar conductances, thermal analyses (DTA, DTG and TG) and ESR measurements. The IR spectral data show that the ligand is bi-basic or tri-basic tetradentate towards the metals. Molar conductances in DMF indicate that the complexes are non-electrolytes. The ESR spectra of solid copper(II) complexes [(HL)(Cu)₂(Cl)₂] · 2H₂O (2) and [(L)(Cu)₃(OH)₃(H₂O)₆] · 7H₂O (6) show axial symmetry of a d _{x²???y ²} ground state; however, [(HL)(Co)] (4) shows an axial type with d _Z ² ground state and manganese(II) complex [(L)(Mn)₃(OH)₃(H₂O)6] · 4H₂O (10) shows an isotropic type. The biological activity of the ligand and its metal complexes are discussed.     

Synthesis, structural characterization and electrochemical studies of new macrocyclic Schiff base containing pyridine head and its metal complexes

A new macrocyclic ligand, 1,3,5-triaza-2,4:7,8:13,14-tribenzo-9,12-dioksa-cyclopentadeca-1,5-diene was synthesized by reaction of 2,6-diaminopyridine and 1,2-bis(2-carboxyaldehyde phenoxy)ethane. Then, its Cu(II), Ni(II), Pb(II), Co(III) and La(III) complexes were synthesized by the template effect by the reaction of 2,6-diaminopyridine and 1,2-bis(2-carboxyaldehyde phenoxy)ethane and Cu(NO₃)₂ · 3H₂O, Ni(NO₃)₂ · 6H₂O, Pb(NO₃)₂, Co(NO₃)₂ · 6H₂O, La(NO₃)₃ · 6H₂O, respectively. The ligand and its metal complexes have been characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV-Vis spectra, magnetic susceptibility, thermal gravimetric analysis, conductivity measurements, mass spectra, and cyclic voltammetry. All complexes are diamagnetic and Cu(II) complex is binuclear. The Co(II) was oxidized to Co(III). The comparative electrochemical studies show that the nickel complex exhibited a quasi-reversible one-electron reduction process, while copper and cobalt complexes gave irreversible reduction processes in DMSO solution.     

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.     

Pyrolytical characterization of transition metal complexes of cobalt,nickel, copper and zinc with ethylenediamine-<Emphasis Type="Italic">N,N</Emphasis>′-diacetate

A series of octahedral complexes, [M(EDDA)(H₂O)₂] · H₂O (where, M⁺² = Co(II), Cu(II), Ni(II) and Zn(II); EDDA, ethylenediamine-N,N′-diacetate), was prepared and studied by means of thermogravimetry (TG) and differential thermal analysis (DTA). Their compositions were investigated by elemental analysis in order to ensure their purity and structural elucidation was based on spectral and magnetic properties. Thermal decomposition of these distorted octahedral complexes, [Ni(EDDA)(H₂O)₂], [Co(EDDA)(H₂O)₂] · H₂O, [Cu(EDDA)(H₂O)₂] · H₂O and [Zn(EDDA)(H₂O)₂] · H₂O came of in one, two, three and four steps, respectively, upon heating to 800 °C, with the loss of organic and inorganic fragments. Ligand decomposed in three steps. The thermal degradation of all the complexes in static air atmosphere started at temperatures lower than those observed for the free ligand degradation (Ni-complex being the only exception). The composition of intermediates formed during degradation was confirmed by microanalysis and IR spectroscopy. The residues corresponded to metal oxide except for Ni(II) and Zn(II) complexes. It was found that thermal stability of the complexes increased in the following sequence:

Novel 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone and Zn(II), Cu(II), Ni(II) and Co(III) complexes: Synthesis,characterization, crystal structure,antioxidant, antimicrobial and antiproliferative activity

New zinc (II), copper (II), nickel (II) and cobalt (III) complexes, [Zn (HL)₂]I₂ (1) , [Cu (HL)Cl₂] (2) , [Cu (HL)Br₂] (3) , [Cu (HL)(H₂O)₂](ClO₄)₂ (4) , [Ni (HL)₂]I₂·H₂O (5) , [Co(L)₂]Cl (6) , [Co(L)₂]NO₃ (7) , [Co(L)₂]I·[Co(L)₂](I₃) (8) were obtained with 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone ( HL ). The isothiosemicarbazone ligand was characterized by NMR (¹H and ¹³C), IR spectroscopy and X-ray diffraction. All the complexes were characterized by elemental analysis, IR, UV–Vis, ESI-MS spectroscopy, molar conductivity, magnetic susceptibility measurements. X-ray diffraction analysis on the monocrystal and powder elucidated the structure of the complexes 1 , 5 , 7 and 8 . The ligand and the complexes were tested for their antioxidant and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Candida albicans. Also, the antiproliferative properties of these compounds on human leukemia HL-60, human cervical epithelial HeLa, human epithelial pancreatic adenocarcinoma BxPC-3, human muscle rhabdomyosarcoma spindle, large multinucleated RD cells and normal MDCK cells have been investigated. The nickel complex 5 and cobalt complexes 6 , 7 showed promising antiproliferative activity and low toxicity.     

Synthesis,characterization, and biological activity studies of copper(II)–metal(II) binuclear complexes of dipyridylglyoxal bis(2-hydroxybenzoyl hydrazone)

A new series of copper(II) mononuclear and copper(II)–metal(II) binuclear complexes [(H₂L)Cu] ? H₂O, [CuLM] ? nH₂O, and [Cu(H₂L)M(OAc)₂] ? nH₂O, n = 1–2, M = Co(II), Ni(II), Cu(II), or Zn(II), and L is the anion of dipyridylglyoxal bis(2-hydroxybenzoyl hydrazone), H₄L, were synthesized and characterized. Elemental analyses, molar conductivities, and FT-IR spectra support the formulation of these complexes. IR data suggest that H₄L is dibasic tetradentate in [(H₂L)Cu] ? H₂O and [Cu(H₂L)M(OAc)₂] ? nH₂O but tetrabasic hexadentate in [CuLM] ? nH₂O (n = 1–2). Thermal studies indicate that waters are of crystallization and the complexes are thermally stable to 347–402°C depending upon the nature of the complex. Magnetic moment values indicate magnetic exchange interaction between Cu(II) and M(II) centers in binuclear complexes. The electronic spectral data show that d–d transitions of CuN₂O₂ in the mononuclear complex are blue shifted in binuclear complexes in the sequences: Cu–Cu > Cu–Ni > Cu–Co > Cu–Zn, suggesting that the binuclear complexes [CuLM] ? nH₂O are more planar than the mononuclear complex. The structures of complexes were optimized through molecular mechanics applying MM ⁺force field coupled with molecular dynamics simulation. [(H₂L)Cu] ? nH₂O, [CuLM] ? nH₂O, and the free ligand were screened for antimicrobial activities on some Gram-positive and Gram-negative bacterial species. The free ligand is inactive against all studied bacteria. The screening data showed that [CuLCu] ? H₂O > [(H₂L)Cu] ? H₂O > [CuLZn] ? H₂O > [CuLNi] ? 2H₂O ≈ [CuLCo] ? H₂O in order of biological activity. The data are discussed in terms of their compositions and structures.     

Synthesis and characterization of new metal complexes of thiosemicarbazone derived from 4-phenyl-3-thiosemicarbazide and chromone-3-carboxaldehyde

Summary The reaction between chromone-3-carboxaldehyde-4-phenylthiosemicarbazone (HCPT) and some hydrated metal salts of Co^II, Ni^II and Cu^II give complexes of the type [Cu(HCPT)Cl₂],[Cu(CPT)BrH₂O],[Cu(CPT)₂]·2H₂O, [Ni(CPT)₂(H₂O)₂]·2H₂O, [Co(CPT)₂(OAc)] and [Co(CPT)₂(H₂O)₂]X·2H₂O (where X=Cl or Br). The metal complexes were characterized by elemental analyses, molar conductivities, and spectal (i.r. and visible) and magnetic studies. I.r. spectra show that the HCPT coordinates in the thione or thiol form and behaves in a bidentate manner. Also, HCPT behaves as an oxidizing agent towards Co^II forming diamagnetic Co^III complexes. An octahedral structure is proposed for both Co^III and Ni^II complexes, while a square-planar structure is proposed for Cu^II complexes on the basis of magnetic and spectral measurements.     

Syntheses, structures, and properties of the Co(II), Ni(II), and Cu(II) complexes with 5-carboxy- and 5-methoxycarbonylpyrazoles

New cobalt(II), nickel(II), and copper(II) complexes based on 5-methoxycarbonyl-3-me-thylpyrazole (MePzCOOMe), [Co(MePzCOOMe)₂(H₂O)₂](NO₃)₂ (I), [Ni(MePzCOOMe)₂(H₂O)₂] (NO₃)₂ (II), and [Cu(MePzCOO)₂(H₂O)] · 3H₂O (III), were synthesized. The compounds were studied by X-ray diffraction analysis, IR spectroscopy, and static magnetic susceptibility. The molecular and crystal structures of complexes I and III were determined by X-ray structure analysis.     

Synthesis,Structure, and Properties of Nickel(II) and Cobalt(II) Coordination Compounds with Optically Active Diaminodioxime (H2L) Derived from 3-Carene. Molecular and Crystal Structures of the [Ni(H2L)(NO3)]NO3 and [Ni(HL)]ClO4 · H2O Complexes

Nickel(II) and cobalt(II) complexes with optically active diaminodioxime (H₂L, the derivative of 3-carene) of the compositions [Ni(H₂L)NO₃]NO₃ (I), Ni(H₂L)Cl₂ (II), [Ni(HL)]ClO₄ · H₂O (III), and Co(H₂L)Cl₂ (IV), were synthesized. According to X-ray diffraction data, the structures of the paramagnetic compound I and diamagnetic complex III are ionic. In the cation of I, the distorted NiN₄O₂ octahedron is formed by the N atoms of the tetradentate cyclic ligand (H₂L molecule) and by the O atoms of NO₃ ^–; anion functioning as bidentate cyclic ligands. In the cation of III, the NiN₄ coordination unit is a distorted square formed upon coordination of the tetradentate cyclic ligand, HL^–; anion. The data of magnetochemistry and UV-Vis, IR, and Raman spectroscopy suggest that paramagnetic complexes II and IV contain a distorted octahedral polyhedron MCl₂N₄ (M = Ni, Co).     

Syntheses and structures of cobalt(II), nickel(II), and copper(II) complexes with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides (O-daap) containing nitrate as the counter ion

Reactions of M(NO₃)₂?·?xH₂O [M?=?Co(II), Ni(II), and Cu(II)] with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides(O-daap) in CH₃CN yield [Co(O-dmap)(NO₃)₂] (1), [Co(O-deap)(NO₃)₂] (2), [Co(O-dpap)(NO₃)₂] (3), [Ni(O-dmap)(H₂O)₃](NO₃)₂] (4), [Ni(O-deap)(H₂O)₂(NO₃)](NO₃)] (5), [Cu(O-deap)(NO₃)₂] (6), and [Cu(O-dpap)(NO₃)₂] (7). X-ray crystal structures of 1, 2, 4, 5, and 7 reveal that O-daap ligands coordinate tridentate to each metal, O–N–O, with nitrate playing a vital role in molecular and crystal structures of all the complexes. The coordination geometry in the two Co(II) complexes, 1 and 2, is approximately pentagonal bipyramidal with nitrate bonded in a slightly unsymmetrical bidentate chelating mode. [Ni(dmap)(H₂O)₃](NO₃)₂ (4) and [Ni(deap)(H₂O)₂(NO₃)](NO₃) (5) exhibit octahedral geometry, the former containing uncoordinated nitrate while the latter has one nitrate coordinated unidentate and the other nitrate outside the coordination sphere. The Cu(II) in [Cu(dpap)(NO₃)₂] (7) occupies a distorted square pyramidal geometry and is linked to two unidentate nitrates, although one nitrate is also involved in a weak interaction with the metal through its other oxygen. IR spectra and other physical studies are consistent with their crystal structural data. O-dmap?=?N,N,N′,N′-tetramethylpyridine-2,6-dicarboxamides; O-deap?=?N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamides; and O-dpap?=?N,N,N′,N′-tetraisopropylpyridine-2,6-dicarboxamides.     

Novel crown-containing porphyrin and its complexes with transition metals

The novel crown-containing porphyrin 5-{4-[(4-hydroxybenzo-15-crown-5)-5-yldiazo]phenyl}-10,15,20-triphenylporphyrin (H₃L) and its transition metal complexes MHL (M = Co(II), Ni(II), Cu(II), and Zn(II)) and AgH₂L were obtained. The compositions and structures of all the compounds were studied by MALDI-TOF mass spectroscopy, electronic absorption and IR spectroscopy. The diamagnetic compounds were additionally characterized by ¹H NMR spectroscopy. It was proved that Co(II), Ni(II), Cu(II), and Zn(II) are coordinated through the pyrrole N atoms, while Ag(I) is coordinated through the hydroxyl O atom and the diazo N atom of H₃L.     

Mass, EPR, IR and electronic spectroscopic studies on newly synthesized macrocyclic ligand and its transition metal complexes

Manganese(II), cobalt(II), nickel(II) and copper(II) complexes have been synthesized with a new tetradentate ligand viz. 1,3,7,9-tetraaza-2,4,8,10-tetraketo-6,12-diphenyl-cyclododecane (L) and characterized by the elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, ¹H NMR, IR, electronic and EPR spectral studies. The molar conductance measurements of the complexes in DMF correspond to be nonelectrolytic nature for Mn(II), Co(II) and Cu(II) while 1:2 electrolytes for Ni(II) complexes. 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) complexes, square-planar for Ni(II) whereas tetragonal for Cu(II) complexes. The ligand and its complexes were also evaluated against the growth of bacteria and pathogenic fungi in vitro.     

Structural studies of metal complexes containing amide ligands

Complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Pd(II) with di-N-phenyl pyromellitic diimide (PhPMDI) and di-N-pyridyl pyromellitic diimide (PyPMDI) were prepared and characterized based on analytical, molar conductance, magnetic, IR, PMR, electronic and ESR data. Based on analytical and molar conductance, the complexes have been formulated as [M(PhPMDA)(H₂O)₂]_n (M = Mn, Fe, Co, Ni), [Cu(PhPMDA)]_n [Pd₂(PhPMDA)Cl₂(H₂O)₂], [M(PyPMDA)]_n (M = Mn, Fe, Co, Ni and Cu) and [Pd₂(PyPMDA)Cl₂] In all these complexes PhPMDA acts as a mononegative bidentate ligand whereas PyPMDA acts as a mononegative tridentate one in the form of amide rather than imide. The geometries of the complexes have been proposed based on the electronic spectra. The various bonding parameters have been calculated from the ESR spectra of Cu(II) complexes.     

Synthesis of metal complexes with a novel ethyldioxolane pendant-arm hexaazamacrocyclic ligand

The coordination capability of a pendant-arm azamacrocyclic ligand L with four ethyldioxolane pendant groups towards transition, post-transition and lanthanide metal ions was achieved. In all cases, complexes with a 2:1 metal:ligand molar ratio were obtained. The complexes were characterized by elemental analysis, MS-FAB, IR, conductivity measurements, ¹H and ¹³C NMR spectroscopy. Crystal structures of [CoL][CoBr_0.5(NO₃)_3.5] and [(H₂O)H₂L][Nd(NO₃)₄(H₂O)₃]NO₃·3.5H₂O have been determined. The [CoL]²⁺ cation contains the Co(II) ion endomacrocyclicly coordinated in a distorted octahedral geometry with a N₆ core. The Nd(III) complex presents a mononuclear exomacrocyclic structure with an 11 coordination environment. π,π-Stacking interactions have been observed between the pyridine rings of the protonated ligand [(H₂O)H₂L]²⁺, and the [Nd(NO₃)₄(H₂O)₃]²⁻ anion.     

Coordination‐directed and Hydrogen‐bonded Assembly of Supramolecular Architectures Constructed from Diverse Coordination of Linear,Triangular, Tetragonal Pyramid,Trigonal Bipyramid,and Octahedral Mononuclear Units

Reaction of a imidazole phenol ligand 4‐(imidazlo‐1‐yl)phenol (L) with 3d metal salts afforded four complexes, namely, [Ni(L)₆] · (NO₃)₂ ( 1 ), [Cu(L)₄(H₂O)] · (NO₃)₂ · (H₂O)₅ ( 2 ), [Zn(L)₄(H₂O)] · (NO₃)₂ · (H₂O) ( 3 ), and [Ag₂(L)₄] · SO₄ ( 4 ). All complexes are composed of monomeric units with diverse coordination arrangements and corresponding anions. All the hydroxyl groups of monomeric cations are used as hydrogen‐bond donors to form O–H ··· O hydrogen bonds. However, the coordination habit of different metal ions produces various supramolecular structures. The Ni^II atom shows octahedral arrangement in 1 , featuring a 3D twofold inclined interpenetrated network through O–H ··· O hydrogen bond and π–π stacking interaction. The Cu^II atom of 2 displays square pyramidal environment. The O–H ··· O hydrogen bond from the [Cu(L)₄(H₂O)]²⁺ cation and lattice water molecule as well as π–π stacking produce one‐dimensional open channels. NO₃^– ions and lattice water molecules are located in the channels. 3 is a 3D supramolecular network, in which Zn^II has a trigonal bipyramid arrangement. Two different rings intertwined with each other are observed. The Ag^I in 4 has linear and triangular coordination arrangements. The mononuclear units are assembled into a 1D chain by hydrogen bonding interaction from coordination units and SO₄^2– anions.     

TG-MS,TG, DTG and DTA methods in study of thermal decomposition of some d-metal complexes with 4,4'-bpy and propionates

The new mixed ligand complexes with formulae M(4-bpy)(C₂H₅COO)₂·2H₂O (where M(II)=Mn, Co, Ni; 4,4'-bpy or 4-bpy=4,4'-bipyridine) and Cu(4-bpy)_0.5(C₂H₅COO)₂·H₂O were prepared and characterized by VIS (for solid compounds of Co(II), Ni(II), Cu(II) in Nujol), IR spectroscopy, X-ray powder diffraction and molar conductance in MeOH, DMF or DMSO. Thermal behaviour of complexes was studied under static conditions in air atmosphere. Corresponding metal oxides were identified as final products of pyrolysis. A coupled TG-MS system was used to analysis of principal volatile thermal decomposition and fragmentation products of isolated complexes under dynamic air and argon atmosphere. The principal species correspond to: C⁺, OH⁺, H₂O⁺, NO⁺, CO₂ ⁺ and other; additionally CO⁺ in argon atmosphere. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.