Crystal Structures of Metal Complexes

This reprint contains 11 papers published in a Special Issue of Molecules entitled "Crystal Structures of Metal Complexes". I will be very happy if readers will be interested in the crystal structures of metal complexes

sw uobaghdad edu iqSynthesis and Characterization of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Hg(II) Complexes with Symmetrical Schiff base

New binuclear Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Hg(II) Complexes of N2S2 tetradentate or N4S2 hexadentate symmetric Schiff base were prepared by the condensation of butane-1,4-diylbis(2-amino ethylcarbamodithioate) with 3-acetyl pyridine. The complexes having the general formula [M2LCl4] (where L=butane-1,4-diyl bis (2-(z)-1-(pyridine-3-ylethylidene amino))ethyl carbamodithioate, M= Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Hg(II)), were prepared by the reaction of the mentioned metal salts and the ligand. The resulting binuclear complexes were characterized by molar conductance, magnetic susceptibility ,infrared and electronic spectral measurements. This study indicated that Mn(II), Ni(II) and Cu(II) complexes have octahedral geometry, while Co(II) Zn(II) and Hg(II) complexes are proposed to be tetrahedral structure .

Synthesis, Spectral Characterization and Antimicrobial Studies of Co(II) Complexes with Tetradentate Schiff bases Derived from Ortho-Phthalaldehyde

A series of cobalt (II) complexes have been synthesized with Schiff bases derived from ortho-phthalaldehyde and various amines in aqueous methanol solution. The newly synthesized Schiff bases and their Co (II) complexes have been characterized  by elemental analysis, magnetic susceptibility, thermal, conductance measurements, mass, IR, electronic, 1H,13C-NMR spectral techniques. These ligands act as tetradentate species and coordinate to the metal center through the different potential donor atoms such as N, O and S. The probable octahedral structures have been assigned to these complexes. All the synthesized Schiff base ligands and Co(II) metal complexes have also been screened for their antimicrobial activities and metal complexes found to be more active than respective Schiff-base ligands

Synthesis, structural, spectral and biological evaluation of metals endowed 1,2,4-triazole

Biologically active triazole Schiff base ligand 2,4-dichloro-6-[(1H-1,2,4-triazol-3-ylimino)methyl]phenol (A) has been synthesized by the condensation reaction of an equimolar amount of 1H-1,2,4-triazole-3-amine and 3,5-dichlorosalicylaldehyde and then it coordinated with salts of metals [VO(IV), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] in 2:1 molar ratio to derive a series of transition metal chelates (1)-(6). All the compounds were characterized by various physical, spectral, analytical techniques and elemental analysis. Spectral characterization and magnetic moment data of complexes revealed square pyramidal geometry for vanadium complex and octahedral for remaining (2)-(6) complexes. Quantum chemical calculation has been carried out to explore optimized geometry and electronic structure of the ligand. Density functional theory (DFT) with B3LYP/6-311+g(d,p) method was performed to determine vibrational bands, frontier molecular orbitals (FMOs) and natural bond analysis (NBO) of the ligand. NBO analysis showed that the ligand bears higher molecular stability because of hyper conjugate interactions. Computational study results revealed that there was a close interaction of theoretical and experimental spectroscopic data. Global reactivity descriptors calculated by the energies of FMOs, indicated ligand to be bioactive. The synthesized compounds were studied for antibacterial, antifungal, antioxidant and antiglycation activity and the results revealed that ligand has remarkable activity which considerably increased upon chelation.                     KEY WORDS: Triazole ligand, Transition metal chelates, Antibacterial, Antifungal, Antioxidant, Computational study   Bull. Chem. Soc. Ethiop. 2020, 34(2), 335-351 DOI: https://dx.doi.org/10.4314/bcse.v34i2.1

Vanadium Compounds as Biocatalyst Models.

Peroxidovanadium(V) and oxidovanadium(IV) compounds have been tested as peroxidase-similar compounds. Their catalytic performance was tested on phenol red and pyrogallol substrates. Bromination kinetic studies revealed Michaelis-Menten behavior with respect to phenol red for both complexes. Catalytic efficiency is ~ 104M−1 min−1. Both vanadium complexes showed the capacity to oxidize pyrogallol, but only the oxidovanadium(IV) complex follows Michaelis-Menten kinetics with respect to this substrate (Km = 1.05 × 10-3 M). Peroxidovanadium(V) complex displayed a more complex mechanism, and further studies became necessary to elucidate it. The structure-activity relationship was also assessed.Fil: Parente, Juliana Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Williams, Patricia Ana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Ferrer, Evelina Gloria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; Argentin

Synthesis and characterization of two novel Schiff base Pd(II) complexes based on 3,5-Diiodo- and 3,5-Dibromosalicylaldehydes

We report on the synthesis and characterization of the two novel Schiff base Pd(II) complexes based on 3,5-diiodo- and 3,5-dibromosalicylaldehydes. Synthesis was made by the condensation method of these aldehydes with p-Anisidine. The structural features of the complexes were comprehensively analyzed by 1H nuclear magnetic resonance, X-ray diffraction, optical, vibrational and X-ray absorption spectroscopies. The analysis of experimental data supported by theoretical simulations at the density functional theory level confirmed the formation of the Pd(II) complexes, and provided detailed information on the local environment of the palladium atoms

Abordagem Teórica por DFT na Caracterização do Benzoato de Zn(II)

The condensation reaction between aminoguanidine bicarbonate and benzoic acid produced 1,2,4-triazole which, after reaction with zinc(II) chloride, led to the formation of a complex, Zn(II)-1,2,4-triazole. This complex decomposes into chloroform leading to the formation of a by-product identified by multinuclear NMR (13C and 1H) as zinc(II) benzoate. Subsequently, a theoretical study, using the Hartree-Fock and DFT methods, was applied to validate zinc(II) benzoate as a byproduct of decomposition through the calculation of the magnetic shielding tensor (NMR), as well as to address some structural characteristics of this compound since zinc compounds present a variety of geometric arrangements and coordination numbers. The theoretical result showed that Zn(II) benzoate is the by-product of the reaction and that it dimerizes in chloroform solution.A reação de condensação entre o bicarbonato de aminoguanidina e o ácido benzoico produziu 1,2,4-triazol que, após reação com cloreto de zinco(II), levou à formação de um complexo, Zn(II)-1,2,4-triazol. Este complexo se decompõe em clorofórmio levando à formação de um subproduto identificado por RMN multinuclear (13C e 1H) como benzoato de zinco(II). Posteriormente, um estudo teórico, utilizando os métodos de Hartree-Fock e DFT, foi aplicado para validar o benzoato de zinco(II) como subproduto da decomposição através do cálculo do tensor de blindagem magnética (RMN), bem como abordar algumas características estruturais deste composto uma vez que compostos de zinco apresentam uma variedade de arranjos geométricos e números de coordenação. O resultado teórico mostrou que o Benzoato de Zn(II) é o subproduto da reação e que o mesmo dimeriza em solução de clorofórmio