DECOMPOSITION OF CHEMICALLY AND ELECTROCHEMICALLY GENERATED NICKEL(III) COMPLEXES WITH N2O2 SCHIFF-BASE LIGANDS

Electrochemical oxidation and oxidation by iodine of nickel(II) complexes of tetradentate Schiff bases, derived from salicylaldehyde and 2-hydroxynaphthaldehyde, in dimethyl sulfoxide solutions yielded nickel(III) complexes, which underwent slow chemical decomposition. The kinetics of decomposition of these nickel(III) species has been studied, and the results compared with those previously reported for decomposition reactions of macrocyclic nickel(III) complexes with tetraaza macrocyclic and porphyrin ligands. It is suggested that decomposition proceeds through an initial intramolecular electron transfer, followed by reaction of the nickel(II) radical complex thus formed with other nickel species or substrates present in solution.