All chemicals used for electrochemical experiments were stored and handled under inert atmosphere. Dry and degassed CH3CN was obtained by three times distillation of HPLC-grade solvent over P4O10 followed by three freeze-pump-thaw cycles. Afterwards the acetonitrile was stored over 3 Å molecular sieve, which was activated at 220°C and 2-3 mbar for 48 h beforehand. Prior to use, the electrolyte n-Bu4NPF6 (98%, Alfa Aesar) was recrystallized five times from 3:1 EtOH/H2O followed by drying at 105°C and 2-3 mbar for 6 days. Purity was checked by 1 H-, C-, F-and 31 P-NMR spectroscopy. Before preparing fresh electrolyte solutions for each experiment, the stored CH3CN was run over a column of neutral alumina, priorly activated at 220°C and 2-3 mbar for 6 days. AgClO4 (≥ 97%, anhydrous, Alfa Aesar) and Ferrocene (98%, Acros Organics) were used without further purification.