Synthesis, crystal structure, electrochemical properties and DFT calculations of three new Zn(II), Ni(II) and Co(III) complexes based on 5-bromo-2-((allylimino)methyl)phenol Schiff-based ligand

Three new Zn, Ni and Co Schiff base complexes, were synthesized. Molecular structures of complexes were determined by single X-ray diffraction studies. The electrochemical studies of Ni and Co complexes in acetonitrile solution showed that both processes of Ni(II)/Ni(I) and Co(III)/Co(II) reduction are electrochemically irreversible. DFT studies and computational results showed that the optimized values are in good agreement with the experimental ones. [Display omitted] •Three new Schiff base complexes, ZnL2(1), NiL2(2) and CoL3(3), were synthesized.•The crystal structures of Zn(II), Ni(II), Co(III) complexes were determined by X-ray diffraction.•The redox behavior of complexes was studied in acetonitrile using cyclic voltammetry.•The optimizations of structures were performed by using B3LYP level. In this work, a new Schiff base ligand (HL: 5-bromo-2-((allylimino)methyl)phenol) was prepared from the reaction of 5-bromo salicylaldehyde and allylamine. Then, three new Schiff base complexes, ZnL2(1), NiL2(2) and CoL3(3), were synthesized through the reaction of Zn(NO3)2·6H2O, Ni(OAC)2·4H2O, and CoCl2·6H2O with the new Schiff base ligand in methanol or chloroform. The ligand and its related complexes were characterized by elemental analysis, FT-IR, UV-Vis spectroscopy, and 1H- NMR technique. The molecular structures of complexes (1–3) were determined by the single crystal X-ray diffraction technique. The crystallographic data revealed that complexes 1 and 2 are four-coordinated by two phenolate oxygen and two imine nitrogen atoms of two Schiff base ligands. On the other hand, the metal center is six-coordinated by three phenolate oxygen and three imine nitrogen atoms of three Schiff base ligands in 3. Eventually, DFT calculations and the study of electrochemical properties were performed on the new three complexes.