Adsorption properties of thermally stable and biologically active polyurea: its synthesis and spectral aspects

Novel polymer metal complexes were prepared by the condensation polymerization of a polymeric ligand with transition metal ions of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). The polymeric ligand was prepared by the addition polymerization of urea with toluene 2,4‐diisocyanate in 1:1 molar ratio. The polymeric ligand and its polymer metal complexes were characterized by elemental analysis, Fourier transform infrared spectroscopy, ¹³C‐NMR, and¹H‐NMR (nuclear magnetic resonance). The geometry was determined by electronic spectra and magnetic moment measurement. Thermogravimetric analysis (TGA) was utilized to find out the degradation process of the polyurea ligand and the polymer metal complexes. The TGA data revealed that all the metal‐containing polyureas are much more thermally stable than the corresponding polyurea ligand. The surface morphology of the polyurea ligand and cobalt(II)‐containing polyureas was determined by scanning electron micrographs. The antibacterial and antifungal activities of all the synthesized polymers were investigated against Staphylococcus aureus, Escherichia coli, and Bacillus subtilis (bacteria) and Aspergillus niger, Candida albicans, and Aspergillus flavus (fungi). These compounds show remarkably good biocidal activities, which were enhanced after complexation with the metal. Batch adsorption studies of the ligand were carried out for malachite green dye, and the polyurea ligand was found to be a good adsorbent for this dye. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis, characterization, and crystal structure of two zinc(II) halide complexes with the symmetrical bidentate Schiff-base ligand (3,4-MeO-ba)2en

Abstract  

In this study two zinc(II) halide complexes with the Schiff-base ligand (3,4-MeO-ba)₂en [N,N′-bis(3,4-dimethoxybenzylidene)ethane-1,2-diamine] have been synthesized and characterized by elemental analyses (CHN), single-crystal X-ray diffraction, Fourier-transform infrared (FT-IR), and ¹H nuclear magnetic resonance (NMR) spectroscopy. The metal-to-ligand ratio was found to be 1:1 within the formula ZnX₂((3,4-MeO-ba)₂en) (X = Br, I). Crystal structure analysis reveals that the coordination geometry around the zinc(II) ions in the two isotypic complexes is distorted tetrahedral. The Schiff-base ligand (3,4-MeO-ba)₂en acts as a chelating ligand and coordinates via two N atoms to the metal center and adopts an (E,E) conformation. The coordination spheres of the metal atoms are completed by the two halide atoms, which are also involved in weak non-classical hydrogen-bonding interactions of the type C–H···X–Zn.     

Syntheses,crystal structures,and antibacterial activities of two cobalt(III) complexes

Syntheses, structures, and antimicrobial activities of cobalt(III) complexes with two tetradentate Schiff-base ligands, (BA)₂en?=?bis(benzoylacetone)ethylenediimine dianion and (acac)₂en?=?bis(acetylacetone)ethylenediimine dianion, and two axial pyridines (py) have been investigated. These complexes were characterized by FT-IR, ¹H-NMR, UV-Vis spectroscopy, and elemental analysis. The crystal structures of the complexes were determined by X-ray crystallography. Single-crystal X-ray diffraction analyses revealed that both complexes have distorted octahedral environments, Schiff-base ligand coordinates cobalt in four equatorial positions, and the two axial positions are occupied by pyridines. The pyridines and Schiff-base ligands are involved in N–H···O hydrogen bonds with perchlorate. Biological activities of the ligands and metal complexes have been studied on Staphylococcus aureus, Escherichia coli, and Bacillus subtilis by the well diffusion method. The activity data show the metal complexes to be more potent than the parent ligand against two bacterial species.     

In vitro antibacterial and antifungal assay of poly‐(ethylene oxamide‐N,N′‐diacetate) and its polymer–metal complexes

A new polyester, poly‐(ethylene oxamide‐N,N′‐diacetate) (PEODA), containing glycine moiety was synthesized by the reaction of oxamide‐N,N′‐diacetic acid and ethylene glycol and its polymer–metal complexes were synthesized with transition metal ions. The monomer oxamide‐N,N′‐diacetic acid was prepared by the reaction of glycine and diethyl oxalate. The polymer and its metal complexes were characterized by elemental analysis and other spectroscopic techniques. The in vitro antibacterial activities of all the synthesized polymers were investigated against some bacteria and fungi. The analytical data revealed that the coordination polymers of Mn(II), Co(II) and Ni(II) are coordinated with two water molecules, which are further supported by FTIR spectra and TGA data. The polymer–metal complexes showed excellent antibacterial activities against both types of microorganisms; the polymeric ligand was also found to be effective but less so than the polymer–metal complexes. On the basis of the antimicrobial behavior, these polymers may be used as antifungal and antifouling coating materials in fields like life‐saving medical devices and the bottoms of ships. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis,antimicrobial screening,and DNA-binding/cleavage of new pyrazole-based binuclear CoII,NiII, CuII,and ZnII complexes

Pyrazolato endogenous bridged binuclear Co^II, Ni^II, Cu^II, and Zn^II complexes were prepared and characterized by spectro-analytical methods. The hexadentate N₄S₂ donor was synthesized by condensation of 3,5-dichloroformyl-1H-pyrazole with thiosemicarbazide in dry ethanol. All the complexes were binuclear and octahedral in nature. The ligand and complexes are screened for antimicrobial and DNA-binding/cleavage activities. The binding/cleavage activities with Escherichia coli DNA are monitored with absorption, hydrodynamic, thermal denaturation, and electrophoresis studies. The ligand possesses significant activity against microbes which is further enhanced upon complexation. The DNA-binding study reveals classical intercalation. The Ni^II and Cu^II complexes exhibit higher binding ability.     

Manganese(III) Schiff-base complexes involving heterocyclic β-diketone and diethylene triamine

Synthesis, spectral, thermal and coordination aspects of pentadentate Schiff-base complexes of the type [Mn(L)(X)] · H₂O [where H₂L = N,N′–diethylamine bis(1-phenyl-3-methyl-4-acetylimino-2-pyrazoline-5-ol) and X=NCS, NO₃, ClO₄, CN or N₃] are reported. The Schiff-base ligand (H₂L) and metal complexes have been characterized by elemental analysis, FT-IR, ¹H-NMR, magnetic measurements, molar conductivity measurements, electronic spectra, cyclic voltammetric and thermal studies. Magnetic moment values are close to 4.9 B.M. indicating high spin complexes lacking exchange interaction. Infrared spectral data suggest coordination of the secondary amino group making the ligand pentadentate. All complexes are electrochemically inactive, indicating high stability. Thermal decomposition of the Schiff-base complexes indicates loss of water of hydration and decomposition of the ligand. Kinetic parameters such as order of reaction (n) and the energy of activation (E _a) are reported using the Horowitz–Metzger method, indicating first order kinetics and giving the activation entropy (ΔS*), the activation enthalpy (ΔH*) and the free energy of activation (ΔG*).     

Coordination polymers of glutaraldehyde with glycine metal complexes: synthesis,spectral characterization,and their biological evaluation

Glycine metal complexes were prepared by the reaction of glycine with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) in 1?:?2 molar ratio. Thereafter their condensation polymerization was done with glutaraldehyde to obtain polymer metal complexes. All the synthesized polymer metal complexes were characterized by elemental analysis, FT-IR, ¹H-NMR, and UV-Vis spectrometry, magnetic susceptibility, and thermogravimetric studies. The analytical data of all the polymers agreed with 1?:?1 molar ratio of metal complex to glutaraldehyde and magnetic moment data suggest that PGG–Mn(II), PGG–Co(II), PGG–Ni(II), and PGG–Cu(II) have an octahedral geometry around the metal atom, whereas the tetrahedral geometry was proposed for PGG–Zn(II) polymer. The PGG–Mn(II) and PGG–Cu(II) showed octahedral geometry. Thermal behavior of the polymer metal complexes was obtained at a heating rate of 10°C?min^?1 under nitrogen atmosphere from 0°C to 800°C. The antimicrobial activities of synthesized polymers were investigated against Streptococcus aureus, Escherichia coli, Bacillus sphaericus, Salmonella sp. (Bacteria), Fusarium oryzae, Candida albicans, and Aspergillus niger (Yeast).     

Pyrazole-based azo-metal(II) complexes as potential bioactive agents: synthesis,characterization, antimicrobial,anti-tuberculosis,and DNA interaction studies

Abstract

In the present investigation, the bioactive azo-dye ligand 1,5-dimethyl-4-[(3-methyl-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-4-yl)diazenyl]-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (L) and its transition metal complexes have been synthesized and characterized by various physical and spectroscopic techniques to elucidate their geometrical structures. The molar conductivity measurements confirmed the non-electrolytic nature of the complexes. EPR spectroscopy indicated that the metal complexes are monomeric in nature and exhibited octahedral geometry. The redox behavior of the copper complex was studied by the cyclic voltammetric technique in DMF solution and the complex showed well-established redox behavior at a scan rate of 0.05 V s^?1. The antimicrobial activity of the ligand and its metal complexes were screened against Escherichia coli, Bacillus subtilis, Aspergillus niger, and Candida albicans, and the results indicated increased activity after coordination of the ligand to the metal ions. The metal complexes exhibited enhanced antitubercular activity after chelation against M. tuberculosis. The DNA-binding experiments showed that the ligand and its metal complexes showed effective binding properties through intercalative mode against CT-DNA. All the synthesized molecules showed partial cleavage of supercoiled plasmid pUC18 DNA.     

Synthesis,structural characterization,antimicrobial, antioxidant and DNA binding studies of some novel homo‐binuclear Schiff base metal (II) complexes

A novel bi‐nucleating Schiff base ligand, 6,6′‐(((1E,1′E)‐thiophene‐2,5‐diylbis (methaneylylidene))bis (azaneylylidene))bis (3,4‐dimethylaniline), and five binuclear M (II) complexes were synthesized. The bi‐nucleating Schiff base ligand and its metal complexes were characterized using various physicochemical techniques, e.g. elemental analyses, spectroscopic methods, conductivity and magnetic moment measurements. The low molar conductance of the complexes in dimethylsulfoxide shows their non‐electrolytic nature. The antibacterial activities were screened against pathogenic bacteria (Staphylococcus aureus, Escherichia coli, Pseudomonas putida and Bacillus subtilis). The antifungal activity was screened against Aspergillus niger, Aspergillus flavus and Rhizoctonia bataicola. The antimicrobial activity data showed that the metal complexes are more potent than the parent Schiff base ligand against microorganisms. The antioxidant activities of the synthesized compounds were investigated through scavenging activity against 2,2‐diphenyl‐2‐picrylhydrazyl, superoxide anion, hydroxyl and 2,2′‐ azinobis (3‐ethylbenzothiazoline‐6‐sulfonic acid) radicals. The complexes have superior radical scavenging activity than the free ligand and the scavenging effects of the Cu (II) complex are stronger than those of the other complexes. DNA binding studies were performed using electronic spectroscopy, fluorometric competition studies and viscosity measurements. The data indicated that there is a marked enhancement in biocidal activity of the ligand under similar experimental conditions because of coordination with metal ions.     

Coordination modes of two flexidentate salicylaldimine ligands derived from N-(3-aminopropyl)morpholine toward zinc and copper

Two flexidentate Schiff-base ligands condensed from salicylaldehyde or 5-chlorosalicylaldehyde with N-(3-aminopropyl)morpholine were prepared in situ and reacted with Zn(II) and Cu(II) salts. Upon complexation, the Schiff bases underwent deprotonation at hydroxyl to act as mono-anionic ligands. When a ligand?:?metal ratio of 2?:?1 was applied, the deprotonated Schiff bases coordinated metal ions through phenolate and imine in a square-planar or tetrahedral geometry. In contrast, 5-chlorosalicylaldimine reacted with the metal ions in a 1?:?1 ratio to form complexes wherein morpholine nitrogen also participates in an N,N,O-tridentate coordination mode. The structures of the complexes were characterized by spectroscopic methods and single-crystal X-ray diffraction.     

Systematische Studie zu den Koordinationseigenschaften des Guanidin‐Liganden Bis(tetramethylguanidino)propan mit den Metallen Mangan,Cobalt, Nickel,Zink, Cadmium,Quecksilber und Silber

The transition metal complexes with the ligand 1,3‐bis(N,N,N′,N′‐tetramethylguanidino)propane (btmgp), [Mn(btmgp)Br₂] ( 1 ), [Co(btmgp)Cl₂] ( 2 ), [Ni(btmgp)I₂] ( 3 ), [Zn(btmgp)Cl₂] ( 4 ), [Zn(btmgp)(O₂CCH₃)₂] ( 5 ), [Cd(btmgp)Cl₂] ( 6 ), [Hg(btmgp)Cl₂] ( 7 ) and [Ag₂(btmgp)₂][ClO₄]₂·2MeCN ( 8 ), were prepared and characterised for the first time. The stoichiometric reaction of the corresponding water‐free metal salts with the ligand btmgp in dry MeCN or THF resulted in the straightforward formation of the mononuclear complexes 1 – 7 and the binuclear complex 8 . In complexes with M^II the metal ion shows a distorted tetrahedral coordination whereas in 8 , the coordination of the M^I ion is almost linear. The coordination behavior of btmgp and resulting structural parameters of the corresponding complexes were discussed in an comparative approach together with already described complexes of btmgp and the bisguanidine ligand N¹,N²‐bis(1,3‐dimethylimidazolidin‐2‐ylidene)‐ethane‐1,2‐diamine (DMEG₂e), respectively.     

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,spectral, and antibacterial screening studies of chelating polymers of bisphenol-A–formaldehyde resin bearing barbituric acid

A new polymeric ligand was synthesized by the reaction of bisphenol-A and formaldehyde in the basic medium, followed by condensation polymerization with barbituric acid in the acidic medium. Polymer metal complexes were prepared by reaction of this resin with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II). The polymeric resin and its metal polychelates were characterized by elemental analysis, FT-IR, ¹³C-NMR, and ¹H-NMR spectra. The geometry of the polymer metal complexes was evaluated by electronic spectra (UV-Vis) and magnetic moment measurement. Thermal stabilities show an increased thermal stability of the metal polychelates compared to the ligand. The antibacterial activities of all the synthesized polymers were investigated against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli, showing good antibacterial activities against these bacteria. Cu(II) polychelate showed highest biocidal activity.     

Cobaltocenium Carboxylate Transition Metal Complexes: Synthesis,Structure, Reactivity,and Cytotoxicity

Cobaltocenium carboxylate is an unusual betaine that functions as a formally neutral carboxylate ligand with late transition metal centers comprising Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Zn²⁺, Cd²⁺, Hg²⁺, and Rh⁺. Structurally, a rich coordination chemistry is observed – from simple monomeric homoleptic complexes to heteroleptic dimeric, trimeric, and polymeric compounds, as shown by X‐ray diffraction of 11 compounds. Chemically, thermal decarboxylation was investigated aiming at the formation of cobaltocenium‐carbene transition metal complexes, in analogy to such chemistry of imidazolium carboxylate betaines. Cytotoxicity studies of cobaltocenium carboxylate transition metal complexes were performed to evaluate the medicinal bioorganometallic potential of these compounds. While cobaltocenium carboxylate was inactive, its complexes with Ag⁺, Cd²⁺, and Hg²⁺ triggered significant cytotoxic effects.     

Synthesis,spectroscopic investigations,and biological activity of metal complexes of N-benzoylthiosemicarbazide

N-Benzoylthiosemicarbazide, HL, was obtained by fusion of benzoylhydrazide and ammonium thiocyanate. Reactions of HL with cobalt(II), nickel(II), copper(II), zinc(II), iron(III), cadmium(II), oxovanadium(IV), and dioxouranium(VI) in 1 : 1 molar ratio yield the corresponding complexes. The N-benzoylthiosemicarbazide may act as a neutral or monobasic bidentate ligand coordinated through NS or NO sites. The structures of the HL ligand and its complexes were identified by elemental analysis, infrared, electronic, mass, ¹H-NMR, and ESR spectra as well as magnetic susceptibility and molar conductivity measurements. Different geometries were obtained for the metal complexes. The ligand and its metal complexes were investigated for antibacterial and antifungal properties. Two Gram-positive bacteria, Staphylococcus aureus and Streptococcus pyogenes, two Gram-negative, bacteria, Pseudomonas fluorescens and Pseudomonas phaseolicola and two fungi, Fusarium oxysporum and Aspergillus fumigatus, were used in this study. The metal complexes were more effective than the free ligand.     

Expanding the Chemistry of Cationic N‐Heterocyclic Carbenes: Alternative Synthesis,Reactivity, and Coordination Chemistry

A new synthetic route to complexes of the cationic N‐heterocyclic carbene ligand 2 has been developed by the attachment of a cationic pentamethylcyclopentadienylruthenium ([RuCp*]⁺) fragment to a metal‐coordinated benzimidazol‐2‐ylidene ligand. The coordination chemistry and the steric and electronic properties of the cationic carbene were investigated in detail by experimental and theoretical methods. X‐ray structures of three carbene–metal complexes were determined. The cationic ligand 2 is a poorer overall electron donor relative to the related neutral carbene, which is evident from cyclic voltammetry (CV) and IR measurements.     

Metal complexes of tetradentate azo-dye ligand derived from 4,4′-oxydianiline: Preparation,structural investigation,biological evaluation and MOE studies

The Cr (III), Mn (II), Fe (III), Co (II), Ni (II), Cu (II) and Cd (II) complexes were prepared by reaction of its metal chlorides with new azo-dye ligand (H₂L). The ligand derived from 4,4′-oxydianiline and 2-amino-4-chlorophenol was synthesized in a 1:2 molar ratio. The structure of the ligand and its metal complexes was investigated using different tools such as elemental analysis (C, H, N and M), molar conductivity, IR, UV–vis, ¹H-NMR, mass spectrometry and thermogravimetric and differential thermogravimetric studies. The data showed that the ligand acted as a N,N,O,O-binegative tetradentate ligand. All metal complexes had a octahedral structure as depicted by spectral and elemental analyses. The conductivity data showed the electrolytic nature of the Cr (III) and Fe (III) complexes while the other complexes were nonelectrolytes. Thermal analysis studies showed the decomposition of the complexes in four to five steps with the weight loss of hydrated water in the first decomposition step followed by the coordinated water and ligand molecules. Biological activity was tested for the prepared compounds against four bacterial species (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) and against two fungal species (Aspergillus fumigatus and Candida albicans). Also, all complexes were screened for anticancer activities against a breast cancer (MCF-7) cell line. The [Co(L)(H₂O)₂] complex showed the lowest IC₅₀ value. Molecular docking is a key tool in computer drug design. Therefore, investigation of protein receptors and ligand interaction plays a vital role in the design of structurally based drugs. As a result, docking studies were investigated for H₂L ligand, [Mn(L)(H₂O)₂] and [Ni(L)(H₂O)₂] complexes with 5KBC, 3V7B and 4G9M receptors.     

Complexation of 4-amino-1,3 dimethyl-2,6 pyrimidine-dione derivatives with cobalt(II) and nickel(II) ions: synthesis,spectral, thermal and antimicrobial studies

Four heterocyclic Schiff-base ligands derived from condensation of 4-amino-1,3 dimethyl-2,6 pyrimidine-dione with 2-hydroxybenzaldehyde, 2-methoxybenzaldehyde, 4-hydroxy-3-methoxybenzaldehyde and 4-(dimethylamino) benzaldehyde, (HL¹, L², HL³and L⁴), respectively, and their Co(II) and Ni(II) complexes have been prepared and characterized via elemental analysis, molar conductance, magnetic moment, thermal and XRPD analysis as well as spectral data (IR, ¹H-NMR, mass and solid reflectance). IR data reveal that the ligands are bidentate neutral ligands except HL¹, which is monobasic tridentate with coordination sites azomethine (N), carbonyl (O) and phenolic (O). Conductance data suggest that all complexes are non-electrolytes, except cobalt(II) complexes of L²and HL³are 1 : 1 electrolytes. The mass spectra confirm the proposed structure of the ligands and their complexes. The solid reflectance spectral data and magnetic moment measurements suggest octahedral, tetrahedral and square planar geometrical structures for the metal complexes. The spectral data were utilized to compute the important ligand field parameters B, β and Dq; LFSE also was calculated. The thermal behavior is also studied. Antibacterial and antifungal properties of the ligands and their complexes show broad-spectrum activities and the metal complexes show higher activity than the free ligands.     

Synthesis,characterization, antimicrobial,and nuclease activity studies of some metal Schiff-base complexes

A Schiff base (L) is prepared by condensation of cuminaldehyde and L-histidine, and characterized by elemental analysis, IR, UV-Vis, ¹H-NMR, ¹³C-NMR, and mass spectra. Co(II), Ni(II), Cu(II), and Zn(II) complexes of this Schiff-base ligand are synthesized and characterized by elemental analysis, molar conductance, mass, IR, electronic spectra, magnetic moment, electron spin resonance (ESR), CV, TG/DTA, powder XRD, and SEM. The conductance data indicate that all the complexes are 1 : 1 electrolytes. IR data reveal that the Schiff base is a tridentate monobasic donor, coordinating through azomethine nitrogen, imidazole nitrogen, and carboxylato oxygen. The electronic spectral data and magnetic measurements suggest that Co(II) and Ni(II) complexes are tetrahedral, while Cu(II) complex has distorted square planar geometry. XRD and SEM show that Co(II), Cu(II), and Zn(II) complexes have crystalline nature, while the Ni(II) complex is amorphous and the particles are in nanocrystalline phase. The in vitro biological activities of the synthesized compounds were tested against the bacterial species, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, and Staphylococcus aureus; and fungal species, Aspergillus niger, Aspergillus flavus, and Candida albicans by the disc diffusion method. The biological study indicates that complexes exhibit more activity than the ligand. The nuclease activity of the ligand and its complexes are assayed on CT DNA using gel electrophoresis in the presence and the absence of H₂O₂. The Cu(II) complex shows increased nuclease activity in the presence of an oxidant when compared to the ligand, Co(II) and Ni(II) complexes.     

Cu(II), Co(II), Ni(II), Mn(II), and Fe(II) metal complexes containing N,N′-(3,4-diaminobenzophenon)-3,5-But2-salicylaldimine ligand: Synthesis,structural characterization,thermal properties,electrochemistry, and spectroelectrochemistry

The synthesis, structure, spectroscopic and electro-spectrochemical properties of steric hindered Schiff-base ligand [N,N′-(3,4-benzophenon)-3,5-Bu^t₂-salicylaldimine (LH₂)] and its mononuclear Cu(II), Co(II), Ni(II), Mn(II) and Fe(II) complexes are described in this work. The new dissymmetric steric hindered Schiff-base ligand containing a donor set of NONO was prepared through reaction of 3,4-diaminobenzophenon with 3,5-Bu^t₂-salicylaldehyde. Certain metal complexes of this ligand were synthesized by treating an ethanolic solution of the ligand with an equimolar amount of metal salts. The ligand and its complexes were characterized by FT-IR, UV–vis, ¹H NMR, elemental analysis, molar conductivity and thermal analysis methods in addition to magnetic susceptibility, electrochemistry and spectroelectrochemistry techniques. The tetradentate and mononuclear metal complexes were obtained by reacting N,N′-(3,4-benzophenon)-3,5-Bu^t₂-salicylaldimine (LH₂) with some metal acetate in a 1:1 mole ratio. The molar conductance data suggest metal complexes to be non-electrolytes.