Redox properties of cobalt chelates with delocalized electronic structure: organometallic derivatives

TLDR: In this paper, the influence of equatorial and axial ligands on the half-wave potentials of reversible electron transfers corresponding to formal redox couples CoIII→ CoII, CoII→ CoI, and to one-electron oxidation, in some series of organometallic cobalt chelates was investigated.

Abstract: Polarographic techniques are employed to investigate the electrode processes and to point out the influence of equatorial and axial ligands on the half-wave potentials of reversible electron transfers corresponding to formal redox couples CoIII→ CoII, CoII→ CoI, and to one-electron oxidation, in some series of organometallic cobalt chelates. Free-energy relationships are found between the E½ and the pKa values of the hydrocarbon acid corresponding to the organic group in the axial position, showing that the effect is due to charge donation from the organic group, decreasing the electron affinity of the particle. The change of equatorial ligand has a parallel effect of E½ of both reduction and oxidation waves.