Cyclic voltammetry of iron dimine complexes in acetonitrile

Abstract

The electrochemical behavior of iron diimine complexes, (H 3C−N=C(R)−C(R′)=N−CH 3) 3Fe(II) (R, R′=H,H;H, CH 3; CH 3, CH 3), and (C 5H 4N−C(R 1)=N(R 2)) 3Fe(II) (R 1, R 2=H, CH 3; CH 3, CH 3) on a platinum working electrode in acetonitrile is described, and compared to that of the parent aromatic complex, tris-(2,2′-bipyridine)Fe(II). One-electron reversible oxidations were found for all the compounds studied. The electrochemical reductions show 2–3 reduction waves in the potential range studied. Only for the complexes of mixed diimine ligands or 2,2′-bipyridine, a pre-adsorption wave is also observed. It is possible to stabilize low valence states with all ligands studied. A formal iron(I) state is described for the first time for all aliphatic diimine complexes, thus showing that the acceptor properties of the diimine complexes do not depend on the presence of the aromatic rings, but on the iron-diimine chromophore.