Novel Nickel (II), Copper (II) and Cobalt (II) Complexes of Schiff Bases A, D and E: Preparation, Identification, Analytical and Electrochemical Survey

Abstract

A novel set of Cobalt(II), Copper(II) and Nickel(II) complexes of ligands, (E)-2-(((2,5-difluorophenyl)imino) methyl)phenol (A), (E)-2,4-dibromo-1-((2-hydroxybenzylidene) amino)anthracene-9,10-dione (D) & (Z)-1-((1-([1,1'-biphenyl]-4-yl)-2-bromoethylidene) amino)-2,4-dibromo anthracene-9,10-dione (E) were synthesized and characterized. Their structures were investigated on the basis of CHN, conductance measurements and spectral studies (H1-NMR & C13-NMR,FT-infrared and Electronic spectroscopies), cyclic voltammetry. It has observed from spectral and analytical studies that metal complexes have the composition of (ML2.X2) and one mole of ligand behaves as bidentate chelating agents around the corresponding metal ion. From solubility test, we obtained that metal complexes of ligands A, D and E had no ionic properties and dissolve partially in polar and slightly in nonpolar solvents. These results confirmed the behavior of metal complexes as weak electrolyte from their low value of molar conductivity. Conductance data and solubility test of the complexes enhanced them to be (1:2 M:L ratio). All data confirmed an octahedral geometry of these complexes and their structures as {[M (A, D or E)2(CH3COO)2], when M= Co or Ni} and {[Cu (A, D or E)2 Cl2]}. Cyclic voltammetry measurements were accomplished of Cobalt(II), Copper(II) and Nickel(II) complexes using Pt wire as counter electrode and Ag/AgNO3 as reference electrode and (Bu4N+PF6+) as supporting electrolyte. The result exhibit the irreversible process showing single one electron transfer process of Cobalt(II) and Nickel(II) complexes and unique quasi-reversible redox couple is attributed to Cu(II) complexes.

Crystal structure and Hirshfeld surface analysis of bis(benzoato-κ2 O,O′)[bis(pyridin-2-yl-κN)amine]nickel(II)

“…1 E g . This spectroscopic feature agrees with the typical d-d transitions of the Ni II ion in a distorted octahedral geometry (Al-Riyahee et al, 2018).…”

A Study of Metal Complexes of 2-picolinic Acid

“…The new band is detected which occurs between the range of 551-524 cm -1 are attributed to the M-O bonding (metal-oxygen) and other band in the range of 449-418 cm -1 is mainly because of metal-nitrogen bonding. 22,23,24 Electronic Spectra of Metal Complexes 25 T h e c o p p e r p e r c h l o r a t e c o m p l e x reveals the band at 19,607 cm -1 is assigned to 4 T 1g (F) 4 T 1g (P) transition having an octahedral geometry. The perchldue to Jahn-Teller distortion.…”

“…Manganese (II) perchlorate complex exhibits one electron reduction corresponding to Mn(II) Mn(I) at E 1/2 value of -0.784V. (=65mV) and irreversible oxidation peak at 1.152V reveals that Mn(II) Mn(III) oxidation 23 . Cobalt (II) perchlorate complex exhibits an irreversible reduction at -0.…”

Synthesis, Spectral Characterization, Antibacterial and Anticancer Evaluation of Novel Isoniazid based Schiff Base Ligand derived Transition Metal Complexes

“…Similar to the reduction process, the oxidation process may involve the oxidation of the cobalt ion or one of the coordinated ligands. The relatively high oxidation potential suggests that the oxidation process requires a significant energy input indicating that the complex has a tendency to remain in a reduced state under typical electrochemical conditions [24,25].…”