Multi-electron Transfer by U(ɪɪ) and Masked U(ɪɪ) Complexes

Complexes of uranium in low oxidation state have shown the ability of activating non-reactive small molecules such as N2. However, the multi-electron transfer required for such activation, remains limited in uranium chemistry. Here, we review our recent research on the use of different strategies to overcome this issue, which has led to the isolation of a diuranium(ɪɪɪ) bridging oxide complex that reacts as a U(ɪɪ) synthon able to effect one-electron transfer per uranium center to N-heterocycles and multi-electron transfer to diphenylacetylene and azobenzene. We also showed that a closely related molecular U(ɪɪ) complex effects the same reactions providing the first unambiguous example of a monouranium four-electron transfer.