The redox behaviour of ferrocene derivatives : III. Ferrocenylacyl complexes (η-C5H5) Fe(η-C5H4-COER3 E = C, Si or Ge; R = Me or Ph

The electrochemical behaviour of the ferrocenylacyl derivatives FcCOER₃] (E = C, Si or Ge; R = Me or Ph) is examined. One-electron oxidations to the substantially stable monocations FcCOER₃]⁺ occur at potentials significantly higher than that observed with ferrocene, but only minor differences hold within the series, independent of the nature of both E and R. In contrast the EPR spectra of the monocations for E = C show that the unpaired electron resides mainly on the iron, whereas for E = Si or Ge the electron density is essentially localized on the C₅H₄COER₃ fragment.