Low-valent iron centers are critical intermediates in chemical and bio-chemical processes. Herein, we show the first example of a low-valent FeI center stabilized in a high-valent polyoxometalate framework. Electrochemical studies show that the FeIII-functionalized molecular vanadium(V) oxide (DMA)[FeIIIClVV 12O32Cl]3− (DMA=dimethylammonium) features two well-defined, reversible, iron-based electrochemical reductions which cleanly yield the FeI species (DMA)[FeIClVV 12O32Cl]5−. Experimental and theoretical studies including electron paramagnetic resonance spectroscopy and density functional theory computations verify the formation of the FeI species. The study presents the first example for the seemingly paradoxical embedding of low-valent metal species in high-valent metal oxide anions and opens new avenues for reductive electron transfer catalysis by polyoxometalates.
- metal oxides