Metal-ligand Ratio Research Articles

Synthesis, Spectral Characterization and Electrochemical Properties of New vic-dioxime Complexes Bearing Carboxylate

Three new vic-dioxime ligands, [N-(ethyl-4-amino-1-piperidine carboxylate)-phenylglyoxime (L1H2), N-(ethyl-4-amino-1-piperidine carboxylate)-glyoxime (L2H2), and N,N′-bis(ethyl-4-amino-1-piperidine carboxylate)-glyoxime (L3H2)], and their Co(II) with Cu(II) metal complexes, were synthesized for the first time. Mononuclear complexes of these ligands with a 1:2 metal-ligand ratio were prepared with Co(II) and Cu(II) salts. The BF 2 + -capped Co(II) and mononuclear complexes of the vic-dioxime were prepared for [Co(L1·BF2)2] and [Co(L2·BF2)2]. The ligands act in a polydentate fashion bonding through nitrogen atoms in the presence of a base, as do most vic-dioximes. The cobalt(II) and copper(II) complexes are non-electrolytes as shown by their molar conductivities (Λ M ) in DMF. The structures of the ligands and complexes were determined by elemental analyses, FT-i.r., u.v.–vis., 1H- and 13C-n.m.r. spectra, magnetic susceptibility measurements, and molar conductivity. The comparative electrochemical studies show that the stabilities of the reduced or oxidized species and the electrode potentials of the complexes are affected by the substituents attached on the oxime moieties of the complexes.

Palladium/1,2-bis(diphenylphosphino) ethane catalysed amination of aryl halides with aliphatic/aromatic amines

The Ullmann coupling of amines with aryl iodide and bromides has been carried out efficiently using Pd(OAc) 2/1,2-bis(diphenylphosphino) ethane [DPPE] in toluene as a solvent. The effects of various parameters such as temperature, solvent, base, catalyst loading and metal–ligand ratio on the reaction system were studied. The reaction is applicable to a wide variety of substituted aryl amines and alkyl amines with different steric and electronic properties.

Synthesis, Characterization, Electrochemical Properties and Antibacterial Activity of Some Transiton Metal Complexes with [(2-hydroxy-1-naphthaldehyde)-3-isatin]-bishydrazone

A bishydrazone was prepared by reacting isatin monohydrazone with 2-hydroxy-1-naphthaldehyde and a series of metal complexes with this new ligand were synthesised by reaction with MnII, FeII, CoII, NiII, CuII and ZnII salts. The complexes were characterised on the basis of elemental analysis, molar conductance, magnetic susceptibility data, u.v.–visible, i.r., e.s.r. and n.m.r. spectral studies, wherever possible and applicable. Analytical data reveal that the nickel(II), copper(II) and zinc(II) complexes possess 1:1 metal–ligand ratios and that manganese(II), iron(II) and cobalt (II) complexes exhibit 1:2 ratios. Infrared spectral data suggest that the bishydrazone behaves as a monobasic tridentate ligand with ONO donor sequence towards the metal ions. X-ray diffraction study of the copper(II) complex indicated an orthorhombic crystal lattice. The e.p.r. spectral data show that the metal–ligand bond has considerable covalent character. The electrochemical behaviour of the copper(II) complex was investigated by cyclic voltammetry (CV). Antibacterial tests of the ligand and the metal complexes were also carried out and it has been observed that the complexes are more potent bactericides than the ligand.

Co(II), Ni(II) and Cu(II) complexes of 1,4-di-(1-hydroxyimino-2-phenyl-2-oxo-ethylamino)benzene

The ligand has been prepared from ω-chloroisonitrosoacetophenone and 1,4-phenylenediamine in the presence of NaHCO3. The ligand have a C=O group and an –NH–R group adjacent to the oxime group. The Ni(II), Cu(II) and Co(II) complexes of the synthesized ligand were prepared and their structures were identified using FTIR, UV-Vis spectral data, elemental analysis, thermal analysis and magnetic moment measurements. The metal-ligand ratios were found to be 3:2. The ligands were found to coordinate to the metal ions via the oxime nitrogen, oxime oxygen, one of the carbonyl group and amide nitrogen atoms. Thermal analyses data reveals that the water in the complexes was found to be non-coordinated to the metal ions. In the trinuclear structures, the metals have the tetrahedral environments.

Solution and Structural Investigations of Ligand Preorganization in Trivalent Lanthanide Complexes of Bicyclic Malonamides

This report describes an investigation into the coordination chemistry of trivalent lanthanides in solution and the solid state with acyclic and preorganized bicyclic malonamide ligands. Two experimental investigations were performed: solution binding affinities were determined through single-phase spectrophotometric titrations and the extent of conformational change upon binding was investigated with single-crystal X-ray crystallography. Both experimental methods compare the bicyclic malonamide (BMA), which is designed to be preorganized for binding trivalent lanthanides, to an analogous acyclic malonamide. Results from the spectrophotometric titrations indicate that BMA exhibits a 10-100x increase in binding affinity to Ln(III) over acyclic malonamide. In addition, BMA forms compounds with high ligand-metal ratios, even when competing with water and nitrate ligands for binding sites. The crystal structures exhibit no significant differences in the nature of the binding between Ln(III) and the BMA or acyclic malonamide. These results support the conclusion that rational ligand design can lead to compounds that enhance the binding affinities within a ligand class.

A voltammetric method for determining free metal activities in aqueous solutions. Part 2: anodic stripping voltammetry of Cd, Cu, Pb and Zn in synthetic and soil solutions

Theory and methodology for determining the free metal activity, (M2+), of Cd, Cu, Pb and Zn by anodic stripping voltammetry is presented. Metal-buffer solutions were prepared to control (M2+), which was varied by using different ligands and by changing pH. Total metal aqueous concentration of 10-6–10-7M and metal-ligand ratios of 1:20M, 0.010M acetate medium were used. Equations for reversible and irreversible systems were interpreted to explain the results. For Cd and Pb (pPb < 10), agreement was found among theory, experimental ASV and (M2+), calculated by using a speciation chemical equilibria programme and stability constants reported in the literature. Kinetic effects were observed for values of pPb > 10. For Cu and Zn, good agreement was found between the theory and calculated (M2+), and between experimental ASV results and calculated (M2+). Experimental ASV results showed Nernstian parallel shifts with regard to theory. Free metal activities in the order of pCd = 12, pCu = 18, pPb = 10 and pZn = 9 were measurable under the experimental conditions tested. Results too showed good agreement between Cu-ISE and Cu-ASV when measuring the free Cu2+ activity in aqueous extracts of four soils. Values of soil-(Cu2+) measured were in the order of 10-5–10-9.

Complexes of Manganese(II), Iron(II), Cobalt(II), Nickel(II), Copper(II), and Zinc(II) with a Bishydrazone

Complexes of manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and zinc(II) with a bishydrazone formed by the condensation of isatin hydrazone with salicylaldehyde were synthesized and characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility data, UV-Visible, IR, and NMR spectral studies. The spectral data revealed that the ligand acted as monobasic tridentate, coordinating to the metal ion through the azomethine nitrogen, phenolate oxygen and carbonyl oxygen of the isatin moiety. Manganese(II), iron(II), and cobalt(II) complexes exhibited 1:2 metal ligand ratio while nickel(II), copper(II), and zinc(II) complexes revealed 1:1 metal ligand stoichiometry. The EPR spectral data of the copper(II) complex revealed that the metal-ligand bond has considerable covalent character. The XRD pattern of the nickel(II) complex showed that the metal complex possesses orthorhombic crystal lattice. The ligand and the metal complexes were screened for their antibacterial activity and it has been observed that the complexes are more potent bactericides than the ligand.

Synthesis and Characterization of a New (E,E)-Dioxime and its Homonuclear Complexes

N′-(4′-Benzo[15-crown-5]naphthylaminoglyoxime (H2L) and its sodium chloride complex (H2L·NaCl) have been prepared from 2-naphthylchloroglyoxime, 4′-aminobenzo[15-crown-5] and sodium bicarbonate or sodium bicarbonate and sodium chloride. Nickel(II), cobalt(II) and copper(II) complexes of H2L and H2L·NaCl have a metal–ligand ratio of 1:2 and the ligand coordinates through the two N atoms, as do most of the vic-dioximes. The BF2+-capped Ni(II), Co(III) and mononuclear complexes of thevic-dioxime were prepared. The macrocyclic ligands and their transition metal complexes have been characterized on the basis of IR, 1H NMR spectroscopy and elemental analyses data.

Synthesis, Characterization and Redox Properties of Three New vic-dioximes and their Nickel(II) Metal Complexes

Three novel vic-dioximes: cyclohexylamine-p-tolylglyoxime (L1H2), t-butylamine-p-tolylglyoxime (L2H2) and sec-butylamine-p-tolylglyoxime (L3H2) were prepared by the reaction of anti-p-tolylchloroglyoxime with cyclohexylamine, t-butylamine and sec-butylamine in absolute THF. The detection of H-bonding in all of the Ni(II) complexes by i.r. revealed the square-planar MN4 coordination of mononuclear complexes. MN4 coordination of the [(L1H)2Ni] complex was also determined by 1H and 13C-n.m.r spectroscopy. Mononuclear complexes with a 1:2 metal-ligand ratio were prepared using Ni(II) salts. All Ni(II) complexes are insoluble in common solvents. The ligands and complexes were characterized by elemental analyses, FT-i.r., u.v.–vis., 1H and 13C-n.m.r. spectra, magnetic susceptibility measurements, thermogravimetric analyses (t.g.a.) and cyclic voltammetry.

New Soluble Coordination Chain Polymers of Nickel(II) and Copper(II) ions and their Biological Activity

A new tetraoxime ligand, (2E, 3E, 9E, 10E)-1, 4, 8, 11-tetraazacyclotetradecane-2, 3, 9, 10-tetrone tetraoxime has been prepared by the template condensation of 1,3-propanediamine and cyanogen-di-N-oxide, obtained by treating (E, E)-dichloroglyoxime in CH2Cl2 with Na2CO3 at −10 °C. The coordination chain polymers {[(pnngH2)2Ni]n (5) and [(pncgH2)2Cu]n(6)} of two transition metal ions, [Ni(II) and Cu(II)] with the vic-dioxime ligand have been prepared. The oxime ligand acts as a polydentate ligand bending through nitrogen atoms in the presence of a base, as do most of the vic-dioximes. In the complexes, the chloride ions coordinate to the nickel and copper ions. The structures of these novel vic-dioxime compounds are proposed on the basis of the elemental analyses, molar conductance data, i.r., and U.v.–visible are presented. Elemental analyses indicate a ligand metal ratio of 1:1 in the coordination polymers. Conductivity measurements have shown that mono- and polynuclear complexes are non-electrolytes. In addition, anti-microbial activities of the compounds have been investigated.

Studies on mononuclear chelates derived from substituted Schiff-base ligands (part 7): synthesis and characterization of a new naphthyliden-p-aminoacetophenoneoxime and its complexes with Co(II), Ni(II), Cu(II) and Zn(II)

In this study, the new ligand, naphthyliden-p-aminoacetophenoneoxime (LH) was synthesized starting from p-aminoacetophenoneoxime and 2-hydroxy-1-naphthaldehyde. Mononuclear complexes with a metal ligand ratio of 1 : 2 have been prepared with Co(II), Ni(II), Cu(II) and Zn(II) salts. Their structures have been elucidated on the basis of elemental analyses, IR, 1H- and 13C-NMR spectra, UV-Vis spectra, magnetic susceptibility measurements, molar conductivity and thermogravimetric analyses (TGA).

The synthesis, characterization and spectral studies of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with N,N-bis(2-{[(2-methyl-2-phenyl-1,3-dioxolan-4-yl) methyl]amino}butyl) N′,N′-dihydroxyethanediimidamide

CoII, NiII, CuII, ZnII and CdII complexes of N,N-bis(2-{[(2-methyl-2-phenyl-1,3-dioxolan-4-yl)methyl]amino}butyl)N′,N′-dihydroxyethanediimidamide (LH2) were synthesized and characterized by elemental analyses, IR, 1H- and 13C-NMR spectra, electronic spectra, magnetic susceptibility measurements, conductivity measurements and thermogravimetric analyses (TGA). The CoII, NiII and CuII complexes of LH2 were synthesized with 1 : 2 metal ligand stoichiometry. ZnII and CdII complexes with LH2 have a metal ligand ratio of 1 : 1. The reaction of LH2 with CoII, NiII, CuII, ZnII and CdII chloride give complexes Ni(LH)2, Cu(LH)2, Zn(LH2)(Cl)2, Cd(LH2)(Cl)2, respectively.

Complex Formation of Dioxovanadium(V) with Glycine and Some Glycyl Peptides

Stability constants for complexes between dioxovanadium(V) and glycine, glycylglycine, glycylalanine, and giycylphenylalanine have been determined by a combination of Potentiometrie and spectrophotometries techniques in aqueous solution at 25 °C and 0.1 mol dm ionic strength (NaClOj). Complex distribution curve depending on pH and metal-ligand ratio is given and influences of the side chains on the stability constants and the stoichiometrics of the formed complexes are given and discussed.

Synthesis, Characterization, Chelating Properties and Anti‐Fungal Activity of 2‐(4‐Phenylpiperazinyl) Methyl‐3‐(8‐Quinolinol‐5‐YL)‐ 4(3H)‐Quinazolinone

A new quinazolinone derivative namely 2‐(4‐phenylpiperazinyl)methyl‐3‐(8‐quinolinol‐5‐yl)‐ 4(3h)‐quinazolinone(HL) was prepared and characterized. Various transition metal (Cu2+, Co2+, Ni2+, Zn2+, Mn2+) chelates of HL were prepared and characterized by metal ligand (M:L) ratio, IR and reflectance spectral studies, magnetic moment, and antimicrobial activity.

The effect of hydrogen-bonding anions on the structure of metal–sulfimide complexes

Investigations into the effects of the choice of anion on the hydrogen-bonding interactions between anions and metal-sulfimide cationic complexes have led to the study of three novel compounds. Hexakis(S,S-diphenylsulfimide)cobalt(II) diiodide S,S-diphenylsulfimide acetonitrile disolvate, [Co(C12H11NS)6]I2.C12H11NS.2C2H3N, crystallizes in the centrosymmetric space group P-1 with Z = 2. Six diphenylsulfimide ligands coordinate to the cobalt centre through their N atoms. Two iodide counter-ions hydrogen bond to the cation through N-H...I interactions, with N...I distances in the range 3.7302 (19)-3.8461 (19) A. One extra molecule of sulfimide is included in the asymmetric unit, regardless of the metal-ligand ratio used in the synthesis, and this sulfimide molecule also hydrogen bonds to one of the iodide counter-ions through one N-H...I hydrogen bond. The reaction of FeCl3.6H2O with S,S-diphenylsulfimide monohydrate yields hexakis(S,S-diphenylsulfimide)iron(III) trichloride, [Fe(C12H11NS)6]Cl3. The complex crystallizes in the centrosymmetric cubic space group Pa-3 and the asymmetric unit contains one-sixth of a formula unit. Two of the chloride anions each hydrogen bond to three sulfimide NH groups on opposite sides of the [Fe(Ph2SNH)6]3+ cation. The third chloride anion does not take part in any strong hydrogen bonding; instead it is surrounded by aromatic groups and is involved in C-H...Cl hydrogen bonds. The reaction of [Pt(Ph2SNH)4]Cl2 with I2 facilitates oxidation of the Pt(II) metal centre to Pt(IV), producing tetrakis(S,S-diphenylsulfimide)diiodoplatinum(IV) dichloride dichloromethane disolvate, [PtI2(C12H11NS)4]Cl2.2CH2Cl2. The crystal structure is centrosymmetric, with the elongated octahedral cationic complex situated on an inversion centre. The chloride anions are hydrogen bonded to the cation through N-H...Cl hydrogen bonds, with two cis NH groups hydrogen bonded to each anion. Strong hydrogen bonding within these three compounds is limited to N-H...halide hydrogen bonds between the cation and two anions, with a three-up/three-down arrangement of the NH groups in the first two compounds. The anions also 'cap' the NH groups in the third compound. In all three cases, the anions are also involved in weaker hydrogen bonds utilizing the plethora of relatively acidic aryl CH groups in the structures.

Synthesis of N-(4 -Benzo[15-crown-5])biphenylaminoglyoxime and Its Complexes with Some Transition Metals

N′-(4′-Benzo[15-crown-5])biphenylaminoglyoxime (H2L) and sodium chloride salt of N′-(4′-benzo[15-crown-5])biphenylaminoglyoxime (H2L · NaCl) have been prepared from 4-biphenylchloroglyoxime, 4′-aminobenzo[15-crown-5], and sodium bicarbonate and sodium chloride. Nickel(II), cobalt(II), and copper(II) complexes with H2L and H2L · NaCl have a metal–ligand ratio of 1 : 2 and the ligand coordinates through the two N atoms, as do most of the vic-dioximes. Their IR spectra and elemental analyses are given, together with 1H NMR spectra of the ligands.

Synthesis, characterization and redox properties of a new vic-dioxime and its transition metal complexes

A novel vic-dioxime, 1,2 dihydroxyimino-1-p-tolyl-3-aza-6-morpholine heptane (LH2) was prepared by reacting anti-p-tolylchloroglyoxime with 4-(3-aminopropyl)morpholine in absolute THF. Mononuclear complexes with a metal–ligand ratio of 1:2 were prepared using CoII, CuII and NiII salts. The ligand and its complexes were characterized by elemental analyses, FT-IR, u.v.–vis., 1H- and 13C-n.m.r. spectra, magnetic susceptibility measurements, thermogravimetric analyses (t.g.a.), and by cyclic voltammetry.

Synthesis and Characterization of Co(II), Ni(II), Cu(II), and Zn(II) Complexes with a New vic-Dioxime (E,E)-N′-Hydroxy-2-(Hydroxyimino)-N-(4-{[(2-Phenyl-1,3-Dioxolan-4yl)Methyl]Amino}Butyl)Ethanimidamide1

A new vic-dioxime ligand containing 1,3-dioxolane ring and 1,4-diaminobutane, (E,E)-N′-hydroxy-2-(hydroxyimino)-N-(4-{[(2-phenyl-1,3-dioxolan-4-yl)methyl]amino}butyl)ethanimidamide (H2L) and the metal mononuclear complexes with a 1 : 2 and 1 : 1 metal–ligand ratio have been prepared with chloride salts Co(II), Ni(II), Cu(II), and Zn(ll) in EtOH. The structures of the ligand and its complexes have been established by microanalyses, IR, UV-VIS, 1H and 13C NMR spectra, elemental analyses, and conductivity and magnetic susceptibility measurements. Also their thermal behavior has been studied by the TGA analysis.

The synthesis and characterization of N-{2-[(1,4-dioxaspiro[4.5]- dec-2-ylmethyl)amino]ethyl}-N′-hydroxy-2-(hydroxyimino)ethanimidamide and some of its transition metal complexes

A new soluble vic-dioxime, N-{2-[(1,4-dioxaspiro[4.5]dec-2-ylmethyl)amino]ethyl}-N′-hydroxy-2-(hydroxyimino)ethanimidamide (LH2 ) has been synthesized and mononuclear complexes have been obtained with Co(II), Ni(II), Cu(II) and Zn(II) salts. Different types of metal complexes, such as [Co(LH)2(H2O)2], [M(LH)2] (M = Ni(II) and Cu(II)) and [Zn(LH)(Cl)(H2O)], were obtained. Co(II), Ni(II) and Cu(II) form complexes with LH2 which have a metal ligand ratio of 1 : 2. Zn(II) forms a complex with H2L which has a metal–ligand ratio of 1 : 1. Structures of these compounds were identified by using elemental analyses, IR, 1H and 13C NMR spectra, electronic spectra, magnetic susceptibility measurements, conductivity measurements and thermogravimetric analyses (TGA).

Synthesis and structures of morpholine substituted new vic-dioxime ligand and its Ni(II) complexes

N, N ′-bis[4-(2-aminoethyl)morpholino]glyoxime ( H 2 L) ( Fig. 1), has been prepared in various yields using three different methods. The most efficient of these methods is the technique of microwave irradiation. The crystal structures of H 2L, and of two nickel(II) complexes 1 and 2 have been determined by single crystal X-ray diffraction. Both nickel(II) complexes have a metal–ligand ratio of 1:2 in which the ligand coordinates through the two nitrogen atoms as do most vic-dioximes. The nickel(II) complexes are either hydrogen ( 1) or boron diphenyl bridged ( 2). Complex 1 was synthesized by reacting H 2L with nickel(II) chloride in refluxing ethanol. Complex 2 was prepared at room temperature in an ethanol solution containing excess NaBPh 4. Elemental analyses, NMR( 1H, 13C), IR and mass data are also presented.