The complexes [Fe₂(CO)₆{μ-SCH₂N(R)CH₂S}] (R = CH₂CH₂OCH₃, 1a; R = ⁱPr, 1b) and [Fe₂(CO)₆(μ-pdt)] 2 (pdt = S(CH₂)₃S) are structural analogues of the [2Fe]_H subsite of [FeFe]H₂ases. Electrochemical investigation of 1 and 2 in MeCN–[NBu₄][PF₆] under Ar and under CO has demonstrated that the reduction can be resolved into two one-electron transfer steps by using fast scan cyclic voltammetry. At slow scan rates the reduction of 1 tends towards a two-electron process owing to the fast disproportionation of the anion, while the two-electron reduction of 2 is clearly favoured in the presence of CO. Substitution of a CO ligand in 2 by a N-heterocyclic carbene results in the destabilisation of the anion. Thus, in MeCN–, thf- or CH₂Cl₂–[NBu₄][PF₆], the electrochemical reduction of Fe₂(CO)₅L_NHC(μ-pdt)] 3 (L_NHC = 1,3-bis(methyl)-imidazol-2-ylidene, 3a; 1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene, 3b) occurs in a single-step, two-electron process at moderate scan rates; under appropriate conditions this process can be separated into two one-electron steps. Density Functional Theory calculations successfully rationalize the effects of the S-to-S linkage on the electrochemistry of the complexes.