Electrochemistry and study of indirect electrocatalytic properties of a novel organometallic Schiff base nickel(II) complex

Abstract

This paper explores the synthesis, characterization and electrocatalytic behavior of a new ferrocenyl-substituted tetradentate Nickel Schiff base complex. The complex, N,N-Bis[5-(N,N-ferrocenmethylaminophenyl)methylsalicylidyne]-1,2-diaminoethane of nickel(II) ((Fc-Me-Ani)2-LNiII), was prepared by heating the tetradentate Schiff base ligand ((Fc-Me-Ani)2-H2L) in the presence of a stoichiometric amount of tetrahydrate nickel(II) acetate salt, dissolved in a mixture of ethanol and methylene chloride at 50°C under N2 atmosphere. The molecular structure of the complex was deduced from elemental analysis, FT-IR, UV-Vis and mass spectrometry. The electrochemical characterization was investigated by cyclic voltammetry on a glassy carbon electrode and the effect of the solvent (methylenechloride (DCM), dimethylformamide (DMF) and dimethylsulfoxide (DMSO)) was analyzed. The electrochemical characterization of the nickel complex reveals the electron-transfer capability of the two electroactive redox moieties, ie. the ferrocenyl moieties (Fc+‏/Fc) and the metallic centre (Ni2+/Ni+). The diffusion coefficient (D) and the standard rate constant (K0) have also been calculated from the cyclic voltammetry and the polarization curves of ferrocenyl redox process. So, they are influenced by both used method and medium. Cyclic voltammetry has also been performed to examine the performances of the electrocatalytical reduction reaction towards two alkylhalides like ethyl chloroacetate and ethyl bromoacetate in DMF solution. The current increase and the cathodic shift of the Ni2+→Ni+ reduction process in the presence of increasing concentrations of these alkyl halides evidence the catalytic effect of the (Fc-Me-Ani)2-LNiII complex in the reduction of these compounds.