Electrochemical reduction of substituted cobalticinium cations in aqueous media

Summary In aqueous base, polarography, coulometry and cyclic voltammetry show that the cobalticinium skeleton is reduced in two monoelectronic and reversible steps, leading successively to cobaltocenes and cobaltocene anions. In acid solutions, the second reduction step is only observed for derivatives having electron withdrawing substituents. The height of the second reduction wave is pH dependent. Two different schemes are discussed for the reduction in acid solution.