Synthesis, characterization, structure, redox property, antibacterial and catalytic activity of tridentate Schiff base cobalt(III), nickel(II) and palladium(II) complexes

Ligand, HL, 2-((2-(benzylthio)phenylimino)methyl)phenol, upon reaction with Co(NO3)3·6H2O, Ni(OAc)2·4H2O and PdCl2 separately afforded complexes [(L)2Co]NO3 (1), [(L)2Ni] (2) and [(L)PdCl] (3) respectively. The new complexes were characterized by usual spectroscopic studies like UV–Vis, IR and NMR and authenticated by X-ray structure determination on [(L)2Co]NO3, [(L)2Ni]. The analysis of crystal structures revealed that in all the complexes the ligand HL binds the metal center as uni-negative anion; L− dissociating phenolic proton and offers (O, N, S) tridentate binding mode to the metal. The compound [Co(L)2]NO3 is tested for in vitro antibacterial activity. Complex 3, acts as a catalyst in Heck reaction for a number of substrates. Complexes 1 and 2 exhibited a quasi reversible oxidative responses at 0.97 and 0.85 V, respectively, versus SCE. The electronic spectra and redox properties of the complexes have been explained with DFT computation.

Graphical abstractComplex [(L)2Co]NO3, [(L)2Ni] and [(L)PdCl] were synthesized and characterized by usual spectroscopy. The redox property of the complexes was examined and correlate with DFT results. The new [(L)PdCl] complex have been used as catalysts for Heck coupling reactions in ambient condition. The complex [Co(L)2]NO3 exhibited antibacterial activity.Figure optionsDownload full-size imageDownload as PowerPoint slide