Impact of the central metal ion on the redox potential of metal complexes. As an example the cyclic voltammograms of complexes of the type M(Dp44mT)2 with different metal centers are shown (M = manganese, iron, cobalt, nickel, copper; Dp44mT = di-2-pyridylketone 4,4-dimethylthiosemicarbazone) (33). The figure illustrates the strong impact of the central metal ion on the redox potential of structurally similar complexes.