Low Valence States of Metal Chelates. V. Tris(1,10‐phenanthroline)cobalt(II) and bis(2,9‐dimethyl‐1,10‐phenanthroline)cobalt(II) perchlorates

D. C. polarography and cyclic voltammetry were used for investigating the reduction processes of the tris(1,10‐phenanthroline)cobalt(II) and bis(2,9‐dimethyl‐1, 10‐phenanthroline)‐cobalt(II) perchlorates in 0.1 M solutions of tetraethylammonium perchlorate in acetonitrile. The first complex gave a four‐step reduction wave; the first two steps were found to be diffusion controlled and reversible reductions from Co(phen)   3 ++ to Co(phen) 3 + to Co(phen)   3 +to Co(phen;)   3 −occured. The second complex gave a six‐step reduction wave; the first three steps were found to be diffusion controlled and were to be considered as successive reversible reductions from Co(2, 9dm‐phen)   2 ++ to Co(2, 9dmphen)   2 + , from Co(2, 9dmphen)   2 +to Co(2, 9dmphen) 2 and from Co(2, 9dmphen) 2 to Co(2, 9dmphen)   2 − .