Electrochemical studies of four organometallic redox couples as possible reference redox systems in 1-ethyl-3-methylimidazolium tetrafluoroborate

The electrochemical behavior of four organometallic redox couples has been studied in the room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate. Diffusion controlled anodic and cathodic peaks were found for the redox couples Fc/Fc(+) (ferrocene/ferrocenium), Cc/Cc(+) (cobaltocene/cobaltocenium) on glassy carbon, platinum and gold. Bis(biphenyl)chromium(l) tetraphenylborate (BCr/BCr+) yielded a well-behaved diffusion controlled pair of cathodic-anodic peaks only on glassy carbon and gold as working electrodes. The electrode reaction of decamethylferrocene was affected by adsorption of the reduced form on all of the three working electrodes employed by us. The applicability of three of the four redox couples studied as candidates for reference redox systems in this ionic liquid is discussed. (C) 2008 Elsevier Ltd. All rights reserved.