Exploring the Electrochemistry of Iron Dithiolene and Its Potential for Electrochemical Homogeneous Carbon Dioxide Reduction

In this work, the dithiolene complex iron(III) bis-maleonitriledithiolene [Fe(mnt)(2)] is characterised and evaluated as a homogeneous CO2 reduction catalyst. Electrochemically the Fe(mnt)(2) is reduced twice to the trianionic Fe(mnt)(2)(3-) state, which is correspondingly found to be active towards CO2. Interestingly, the first reduction event appears to comprise overlapping reversible couples, attributed to the presence of both a dimeric and monomeric form of the dithiolene complex. In acetonitrile Fe(mnt)(2) demonstrates a catalytic response to CO2 yielding typical two-electron reduction products: H-2, CO and CHOOH. The product distribution and yield were governed by the proton source. Operating with H2O as the proton source gave only H-2 and CO as products, whereas using 2,2,2-trifluoroethanol gave 38 % CHOOH faradaic efficiency with H-2 and CO as minor products.