Strong Medium and Counterion Effects upon the Redox Potential of the 12-Tungstocobaltate(III/II) Couple.

This is the authors' abstract. We don't add key points for this paper.

The 12-tungstocobaltate(III/II) redox couple, both oxidation states being highly negatively charged (5-/6-), is strongly influenced by the nature of the counterion present. In particular, tetraalkylammonium ions decrease E-degrees[Co(III)/(II)] significantly, relative to that measured in the presence of alkali-metal ions in an organic solvent such as acetonitrile, thus causing large decreases in redox reactivity with respect to oxidation. An increasing proportion of water in the solvent increases E-degrees. The redox properties of the hexachloroiridate(IV)/(III) couple are affected by cations in a similar way.