STRONG MEDIUM AND COUNTERION EFFECTS UPON THE REDOX POTENTIAL OF THE 12-TUNGSTOCOBALTATE(III/II) COUPLE
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 o [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