Lateral macrobicyclic compartmental mono and binuclear nickel(II) complexes derived from phenolate ligands: Synthesis, spectral, electrochemical and kinetic studies

Abstract

A novel macrobicyclic ditopic ligand derived from the precursor compound 3,4:10,11-dibenzo-1,13[ N, N′-bis{(3-formyl-2-hydroxy-5-methyl)benzyl}diaza]-5,9-dioxocycloheptadecane has been synthesized in the presence of metal ion via template method. Various mono and binuclear nickel(II) complexes of type [NiL](ClO 4) and [Ni 2L](ClO 4) 2 have been synthesized in order to examine electrochemical and kinetic studies on the basis of macrocyclic ring size. Cyclic voltammetry and controlled electrolysis studies indicate that the nickel(II) complexes undergo quasireversible one electron reduction and oxidation. All the nickel(II) complexes have square planar geometry and EPR silent. The examination of kinetics of the hydrolysis of 4-nitrophenyl phosphate vindicates that the catalytic activities of the complexes are found to increase with macrocyclic ring size of the complexes. As, the macrocyclic ring size of the complexes increases, the spectral, electrochemical and catalytic studies of the complexes show remarkable variation due to distortion in the geometry around nickel(II) centre.