Electrochemical and NMR spectroscopic studies of selenium- and tellurium-substituted ferrocenes I: ferrocenyl alkyl chalcogenides [Fe(η-C5H5)(η-C5H4ER)]

A series of 22 ferrocenyl alkyl selenides and tellurides has been prepared from the diferrocenyl dichalcogenides. The compounds have been characterised by mass spectrometry, multinuclear NMR spectroscopy, cyclic and differential pulse voltammetry. There is a close correlation between the 77Se and 125Te chemical shifts of analogous compounds, with δ(125Te)/δ(77Se)=1.60. Other trends in the NMR data are also apparent. All the compounds studied undergo a one electron reversible oxidation at slightly more positive potentials than ferrocene itself. In addition, the tellurides exhibit a second quasi-reversible process at higher potentials, which appears to be chalcogen-based. There is no obvious correlation between the electrochemical results and the NMR spectroscopic data.