A Terminal Fe^III–Oxo in a Tetranuclear Cluster: Effects of Distal Metal Centers on Structure and Reactivity

Tetranuclear Fe clusters have been synthesized bearing a terminal Fe^III–oxo center stabilized by hydrogen-bonding interactions from pendant (tert-butylamino)­pyrazolate ligands. This motif was supported in multiple Fe oxidation states, ranging from [Fe^II₂Fe^III₂] to [Fe^III₄]; two oxidation states were structurally characterized by single-crystal X-ray diffraction. The reactivity of the Fe^III–oxo center in proton-coupled electron transfer with X–H (X = C, O) bonds of various strengths was studied in conjunction with analysis of thermodynamic square schemes of the cluster oxidation states. These results demonstrate the important role of distal metal centers in modulating the reactivity of a terminal metal–oxo.