The electrochemical oxidation of ruthenocene in various room temperature ionic liquids

The electrochemical behavior of ruthenocene, RuCp2, was investigated on both a platinum microdisk electrode and a platinum macroelectrode in six different room temperature ionic liquids of varying viscosity, at a range of temperatures and concentrations. It was observed that the redox behavior of RuCp2 is not well understood in both aqueous and non-aqueous media. A process involving the one electron oxidation of RuCp2 to the [RuCp2]+ monocation, followed by dimerization to form the [Cp2Ru–RuCp2]2+ species has been speculated although, chronoamperometry suggests that the oxidation of RuCp2 proceeds via a two-electron process. For this reason, it is believed that an ECE mechanism proceeds in which the electrogenerated [RuCp2]+ monocation undergoes a nucleophilic reaction with the anions of the ionic liquid media, in a chemical step which facilitates the transfer of a second electron.

► We investigate the oxidation of ruthenocene in six room temperature ionic liquids. ► Chronoamperometry shows that this is a two-electron process in all liquids. ► The reaction proceeds as an ECE mechanism and is anion independent.