Macrocyclic butterfly iron cluster complexes: electrochemical investigations

Abstract

The article primarily highlights the electrocatalytic activity towards proton reduction of macrocyclic tetranuclear iron complexes [Fe2(μ-S(CH2)nS-μ)(CO)6]2 (n = 4, 1 and n = 6, 2) with both acetic acid and trifluoroacetic acid as proton sources. Further, the electrochemical results have been compared with the analogous pentanedithiolate-bridged tetranuclear complex, [Fe2(μ-S(CH2)5S-μ)(CO)6]2 A. The turnover frequency (TOF, acetic acid) for complexes 1 and 2 was found to be 5.7 h−1 and 9.1 h−1, respectively. An ECEC catalytic cycle (acetic acid) has been proposed for the tetranuclear iron complexes based on the experimental data and known literature. The article primarily highlights the electrocatalytic activity towards proton reduction for macrocyclic tetranuclear iron complexes [Fe2(μ-S(CH2)6S-μ)(CO)6]2, (n = 4 and 6) 1 and 2. Further comparisons have been made with the analogous pentanedithiolate-bridged complex, [Fe2(μ-S(CH2)5S-μ)(CO)6]2 A. The influence on electrochemical properties was noted with an increase in chain length of the dithiols from n = 4 to 6 in the macrocyclic complexes, which is supported by both cyclic voltammetry and bulk electrolysis measurements.