Adaptive Mo‐Fe‐S Clusters: Consistent Redox Behavior Versus Reversible Structural Transformations

Iron-sulfur clusters are critical in a number of important biological processes, where their structural integrity can be maintained or reversibly transformed. However, it remains ambiguous how Fe-S clusters adapt to electrochemical demands for electron transport through redox-induced structural transformations. In this study, three Mo-Fe-S clusters comprising similar or distinct cores with [Mo₂Fe₂] metal centers in different oxidation states have been synthesized. These chemically interconvertible clusters exhibit strikingly similar cyclic voltammetry (CV) curves, irrespective of the structural differences in the core. Subsequent investigations indicate that the chloride ligand in cluster 2 is spontaneously replaced by the solvent molecule in solution and therefore only the solvent-ligated species exhibits an observable redox behavior that is almost identical to that of the chloride-free clusters 3 and 4. A comprehensive analysis of the redox behavior suggests that the intriguing redox events in the CV curves can be correlated to the electrochemical transformations between the chloride-free clusters. This work provides an insight into how Fe-S clusters maintain a stable redox behavior through structural transformations that can facilitate electron transfer in certain cases.