A comparative electrochemical study of the iron-sulfur cluster series Fe 4S xCp 4 (x=4–6) in benzonitrile

Abstract

The electrochemical redox behaviour of the compounds Fe 4S xCp 4 (x=4–6) has been investigated at a platinum electrode in benzonitrile solutions, using pulse polarographic and cyclic voltammetric techniques. In this solvent Fe 4S 4Cp 4 exhibits four reversible oxidation reactions, earlier noted in acetonitrile, and a thus far unknown irreversible reduction. Fe 4S 5Cp 4 shows two reductions one of which is reversible, and three reversible oxidations. Fe 4S 6Cp 4 shows a reversible reduction and two reversible oxidations, and also a third, previously undetected, irreversible one-electron oxidation. Thus far not reported detailed electrochemical data for these compounds (e.g. current functions and reversibility criteria) are measured under the same experimental conditions. In this way a detailed comparative study of the electrochemical properties of the Fe 4S xCp 4 compounds is possible. Some attention is paid to the nature of the decomposition products resulting from the irreversible transitions.