Synthesis, characterization, and electrochemical study of a new tetradentate nickel(II)-Schiff base complex derived from ethylenediamine and 5′-(N-methyl-N-phenylaminomethyl)-2′-hydroxyacetophenone

A tetradentate Schiff base ligand (3) has been synthesized via the reaction of 5′-(N-methyl-N-phenylaminomethyl)-2′-hydroxyacetophenone (2) with a stoichiometric amount of ethylenediamine in absolute ethanol. Compound 2 was prepared by reaction of 5′-chloromethyl-2′-hydroxyacetophenone (1) with N-methylaniline, in the presence of sodium bicarbonate in tetrahydrofuran. Compound 1, on the other hand, was obtained through a reaction between a hydrochloric acid–formaldehyde mixture and 2′-hydroxyacetophenone. Refluxing a mixture of the Schiff base (3) and a stoichiometric amount of nickel(II) acetate tetrahydrate in absolute ethanol at 50 °C under a nitrogen atmosphere afforded the expected tetradentate nickel(II)-Schiff base coordination compound (4). Compounds 1–4 have been characterized with the aid of a number of techniques: UV–Vis spectrophotometry; FT-IR, 1H NMR, 13C NMR, and mass spectrometry; and elemental analysis. Cyclic voltammetry has been employed to investigate the redox behavior of compound 4 as well as the ability of the electrogenerated nickel(I) form of 4 to catalyze the reduction of 1-iodooctane.

Graphical abstractA new tetradentate nickel(II)-Schiff base complex has been synthesized, its electrochemical behavior has been characterized, and the catalytic reduction of 1-iodooctane by its electrogenerated nickel(I) counterpart has been revealed.Figure optionsDownload full-size imageDownload as PowerPoint slide