Polarographic Studies of Metallic Complexes. I. Oxalato-ammine, Glycinato-ammine and Ethylenediamine-ammine Series of Cobalt (III) Complexes

The ions [Co oxn(NH3)6−n](2l−3)−, [Co glyn(NH3)6−n](3−l)+,[Co enn(NH3)6−n]3+, [Co en2 gly]2+ and [Co en2 ox] + were all reduced irreversibly in two steps at the dropping mercury electrode. The first diffusion current corresponds to the reduction, CoIII→CoII and the second to the reduction, CoII→Co0. The diffusion current and the concentration were linearly related. The half wave potential of the first wave of the cobalt (III) complexes shifts to negative direction in the following order of the ligands: ox2−, gly−, NH3, en.