Unprecedented Tetravalent Uranium Photocatalysts for Efficient C(sp3)─C(sp3) Bond Cleavage and Formation

Abstract

Photocatalysis is a pivotal area in synthetic chemistry. Despite extensive application potential in nuclear industry, uranium-based photocatalysts are historically limited to uranyl(VI/V) redox cycle. Here, we report the discovery of the first tetravalent uranium [U(IV)] photocatalyst that enables efficient C(sp³)─C(sp³) bond cleavage and formation under ideal visible light. The U(IV) alkoxy species mediates C─C bond cleavage in a wide range of cycloalkanols and promotes their coupling with electron-deficient alkenes, providing access to previously unattainable molecular architectures. These U(IV) alkoxy complexes, fully characterized by X-ray diffraction and magnetic studies, exhibit exceptional photocatalytic efficiency. Quantum chemical studies reveal that the energy barrier for C─C bond cleavage and formation is reduced to below 10 kcal · mol⁻¹ under visible light excitation. This work introduces a new mechanistic paradigm for uranium-based photocatalysis and positions U(IV) alkoxy complexes as a versatile platform for bond activation and functionalization, expanding the potential applications of depleted uranium in synthetic chemistry.