Six-coordinate oxime-imine cobalt(III) complexes with amino acid co-ligands; synthesis and characterisation

In this publication, several six coordinate Co(III)-complexes are reported. The reaction of 2,3-butanedione monoxime with ethylenediamine or o-phenylenediamine in mole ratios of 2:1 gave the tetradentate imine-oxime ligands diaminoethane-N,N`-bis(2-butylidine-3-onedioxime) H2L1 and o-phenylenediamine-N,N`-bis(2-butylidine-3-onedioxime), respectively. The reaction of H2L1 and H2L2 with Co(NO3)2, and the amino acid co-ligands (glycine or serine) resulted in the formation of the required complexes. Upon complex formation, the ligands behave as a neutral tetradantate species, while the amino acid co-ligand acts as a monobasic species. The mode of bonding and overall geometry of the complexes were determined through physico-chemical and spectroscopic methods. These studies revealed octahedral geometry about Co(III) complexes in which the co-ligands bound through the amine and the carboxylate groups. Molecular structure for the complexes have been optimised by CS Chem 3D Ultra Molecular Modelling and Analysis Program and supported six coordinate geometry

Metal Complexes of Macrocyclic Schiff-Base Ligand: Preparation, Characterisation, and Biological Activity

A new macrocyclic multidentate Schiff-base ligand Na4L consisting of two submacrocyclic units (10,21-bis-iminomethyl-3,6,14,17-tricyclo[17.3.1.18,12]tetracosa-1(23),2,6,8,10,12(24),13,17,19,21,-decaene-23,24-disodium) and its tetranuclear metal complexes with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) are reported. Na4L was prepared via a template approach, which is based on the condensation reaction of sodium 2,4,6-triformyl phenolate with ethylenediamine in mole ratios of 2 : 3. The tetranuclear macrocyclic-based complexes were prepared from the reaction of the corresponding metal chloride with the ligand. The mode of bonding and overall geometry of the compounds were determined through physicochemical and spectroscopic methods. These studies revealed tetrahedral geometries about Mn, Co, and Zn atoms. However, square planar geometries have been suggested for NiII and CuII complexes. Biological activity of the ligand and its metal complexes against Gram positive bacterial strain Staphylococcus aureus and Gram negative bacteria Escherichia coli revealed that the metal complexes become more potentially resistive to the microbial activities as compared to the free ligand. However, these metal complexes do not exhibit any effects on the activity of Pseudomonas aeruginosa bacteria. There is therefore no inhibition zone

Synthesis And Characterization of Novel Functionalized Tetradentate Ligand Type H3NS3 And Its Metal Complexes With Re(V), Ni(II), Cu(II), Cd(II) & Hg(II)

This work represents the preparation of the tetradentate ligand H3NS3 (H3L) andits metal complexes with rhenium(V), nickle(II), copper(II), cadmium(II) andmercurry(II) metal ions. The ligand and its complexes were characterized when neededby Infrared, Ultraviolet–visible, HPLC, Mass, 1H nuclear magnetic resonance, andatomic absorption spectroscopic techniques, elemental analysis, and electricalconductivity. The proposed structure for (H3NS3) with Re(V) is square pyramidal, withNi(II) is distorted square planar, and with the rest of metal ions is distorted tetrahedra

Co(II) and Cd(II) Complexes Derived from Heterocyclic Schiff-Bases: Synthesis, Structural Characterisation, and Biological Activity

New monomeric cobalt and cadmium complexes with Schiff-bases, namely, N′-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]furan-2-carbohydrazide (L1) and N′-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]thiophene-2-carbohydrazide (L2) are reported. Schiff-base ligands L1 and L2 were derived from condensation of 3-hydroxy-4-methoxybenzaldehyde (iso-vanillin) with furan-2-carboxylic acid hydrazide and thiophene-2-carboxylic acid hydrazide, respectively. Complexes of the general formula [M(L)2]Cl2 (where M = Co(II) or Cd(II), L = L1 or L2) have been obtained from the reaction of the corresponding metal chloride with the ligands. The ligands and their metal complexes were characterised by spectroscopic methods (FTIR, UV-Vis, 1H, and 13C NMR spectra), elemental analysis, metal content, magnetic measurement, and conductance. These studies revealed the formation of four-coordinate complexes in which the geometry about metal ion is tetrahedral. Biological activity of the ligands and their metal complexes against gram positive bacterial strain Bacillus (G+) and gram negative bacteria Pseudomonas (G−) revealed that the metal complexes become less resistive to the microbial activities as compared to the free ligands

N,N'-Bis(di-phenyl-meth-yl)benzene-1,4-di-amine.

The complete molecule of the title compound, C32H28N2, is generated by crystallographic inversion symmetry. The dihedral angles between the central aromatic ring and the pendant adjacent rings are 61.37 (16) and 74.20 (14). The N— H group does not participate in hydrogen bonds and there are no aromatic – stacking interactions in the crystal

Synthesis and Characterization of Tripodal Tetradentate Ligand Type NS3 and its Complexes with Re(V), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II)

This work represents the preparation of the starting material, 3-chloro-2-oxo-1,4-dithiacyclohexane (S) using a new method. This material was reacted with, 4-phenylthiosemicarbazide to give (H3NS3) as a tetradentate ligand H3L. New complex of rhenium (V) with this ligand of the formula [ReO(L)] was prepared. New complexes of the general formula [M(HL)] of this ligand when reacted with some metal ions where: M = Ni(II), Cu(II), Cd(II), Zn(II), Hg(II) have been reported. The ligand and the complexes were characterized by infrared, ultraviolet–visible, mass, 1H nuclear magnetic resonance and atomic absorption spectroscopic techniques and by (HPLC), elemental analysis, and electrical conductivity. The proposed structure for H3L with Re (V) is square pyramidal, while Ni(II) complex was square planar geometry, and with the rest of metal ions are distorted tetrahedral

Diethyl 2,2′-({[1,4-phenylenebis(azanediyl)]bis(methylene)}bis(1H-pyrrole-2,1-diyl))diacetate

The complete molecule of the title compound, C24H30N4O4, is generated by crystallographic inversion symmetry. The molecule is S-shaped and the pyrrole groups have an anti or trans confirmation with respect to the central benzene ring, to which they are inclined by 76.38 (9)°. In the crystal, molecules are linked via C—H...O hydrogen bonds, forming layers parallel to the ac plane. Within the layers there are C—H...π interactions present. There are, however, no significant interactions between the layers

Studies of rheniumtricarbonyl complexes of tripodal pyridyl-based ligands

Protagonist in Chemistry Jonathan R. DilworthThe reaction of N-benzoyl and N-acetyl tris(pyridin-2-yl)methylamine 1b and 1c (LH = tpmbaH and tpmaaH) with [Re(CO)5Br] has been investigated and shown to proceed via the initial formation of a cationic rheniumtricarbonyl complex [(LH)Re(CO)3]Br in which coordination of the ligand occurs via the three pyridine rings. For tpmbaH 1b, but not tpmaaH 1c, this initial complex 2b readily undergoes the loss of HBr to give a neutral octahedral complex 4b [(L)Re(CO)3] where coordination occurs via two of the pyridine rings and the deprotonated amide nitrogen. The 1H NMR spectrum of the latter complex 4b is very unusual in that at room temperature the signals for the 3-H protons on the coordinated pyridine rings are not visible due to extreme broadening of these resonances. Comparison with the analogous complex 7 from N-benzoyl bis(pyridin-2-yl)methylamine 6b (bpmbaH) confirms that this is due to rotation of the uncoordinated pyridine ring. The structure of the cationic complex 3d [(LH)Re(CO)3]Br formed from N-benzyl tris(pyridin-2-yl)methylamine 1d (bz-tpmaH) is also discussed. The crystal structures of complexes [(tpmba)Re(CO)3] 4b, [(bz-tpmaH)Re(CO)3]Br 3d and [(bpmba)Re(CO)3] 7 have been determined. In all complexes the coordination geometry around Re is distorted octahedral with a fac-{Re(CO)3}+ core.Peer reviewe

Crystal structure of diethyl 3,3′-{2,2′-(1 E )-[1,4-phenylenebis(azan-1-yl-1-ylidene)]bis(methan-1-yl-1-ylidene)bis(1 H -pyrrole-2,1-diyl)}dipropanoate

The complete molecule of the title compound, C26H30N4O4, is generated by crystallographic inversion symmetry. The dihedral angle between the planes of the benzene and pyrrole rings is 45.20 (11)°; the N atom bonded to the the benzene ring and the pyrrole N atom are in a syn conformation. The side chain adopts an extended conformation [N—C—C—C = 169.07 (17)° and C—O—C—C = −176.54 (17)°]. No directional interactions could be identified in the crystal packing

Improvement of Limestone-Based CO₂ Sorbents for Ca Looping by HBr and Other Mineral Acids

The effects of mineral-acid doping on the long-term reactivity of limestone-based sorbents for CO₂ capture was investigated in this work. Havelock (Canada), Longcliffe (U.K.), and Purbeck (U.K.) limestones were doped with a range of mineral acids (HCl, HBr, HI, and HNO₃), and the effects of concentration were also studied. Doped samples were subjected to repeated cycles of carbonation and calcination in a fluidized-bed reactor. The experimental results showed that HBr and HCl as dopants with a 0.167 mol % doping concentration significantly improved the long-term reactivity of Havelock and Longcliffe limestones (doping with HI marginally improved the reactivity); however, doping Havelock limestone with a similar concentration of HNO₃ reduced its CO₂ uptake. Purbeck limestone was not significantly improved in reactivity by any dopant. Gas adsorption analyses showed that sorbents have a very small surface area: less than 4 m²/g. The pore size distribution appears to change significantly upon doping for those sorbents that are improved by doping, and it is likely that optimizing the pore size distribution upon cycling is one reason for the enhanced reactivity observed. The pore-size distributions of the initially calcined limestones and the changes thereof with cycling and doping explain the differences in the behaviors of the limestones