Electrochemical and kinetic response of heterobinuclear Ni(II)Zn(II) complexes derived from unsymmetrical lateral macrobicyclic tricompartmental ligands

Using the precursor compound 3,4:10,11-dibenzo-1,13[N,N′-bis{(3-formyl-2-hydroxy-5-methyl)benzyl}diaza]-5,9-dioxocyclopentadecane, a series of macrobicyclic heterobinuclear Ni(II)Zn(II) complexes have been synthesized from the corresponding mononuclear nickel(II) complexes via a template method by Schiff’s base condensation. Electrochemical and kinetic studies of the complexes have been carried out on the basis of macrocyclic ring size. Cyclic voltammetry and controlled electrolysis studies indicate that the nickel(II) metal ion in the heterobinuclear complexes undergo quasireversible one electron reduction and oxidation, whereas the zinc(II) metal ion does not undergo any reduction and oxidation. All the heterobinuclear Ni(II)Zn(II) complexes are ESR inactive and diamagnetic in nature. The kinetics of hydrolysis of 4-nitrophenyl phosphate explores that the catalytic activities of the complexes are found to increase with macrocyclic ring size of the complexes. As the macrocyclic ring size increases, the spectral, electrochemical and catalytic studies of the complexes show variation due to distortion in the geometry of metal centre.

Spectral, electrochemical and kinetic studies of heterobinuclear Ni(II)Zn(II) complexes were carried out. Cyclic voltammetric studies show quasireversible one electron reduction and oxidation wave due to the reduction of Ni(II) to Ni(I) and Ni(II) to Ni(III) and Zn(II) ion does not undergo reduction or oxidation. The catalytic activities of the complexes increase with increase in macrocyclic ring size. Macrocyclic ring size influences the spectral, electrochemical (reduction potential) and catalytic properties of the complexes.Figure optionsDownload as PowerPoint slide