In 1988, Darchen et al. investigated electrochemically a group of diiron hexacarbonyl complexes, [Fe2(μ-SR)2(CO)6] (R = Me, C2H5, or −SRRS− = pdt, edt), and their electrocatalytic substitution reactions with P(OMe)3[25]. In their proposed mechanism, it was suggested that the catalytic species was the dianion of the investigated complex, [Fe2(μ-SR)2(CO)6]2−. Reaction of this dianion with the ligand produced another dianion, [Fe2(μ-SR)2(CO)5P(OMe)3]2−, which reacted subsequently with the precursor to regenerate the catalytic species via a two-electron process.