Uranyl Tris(benzoate) Photocatalysts for Site-Selective Hydrocarbon Functionalization.

Area of Science:

• Inorganic Chemistry
• Photocatalysis
• Organic Synthesis

Background:

• The uranyl dication ([UO2]2+) is a potent photocatalyst for C-H bond functionalization through hydrogen atom abstraction (HAA).
• Uranyl ion photocatalysis is underexplored, with most studies using simple uranyl salts like uranyl nitrate (U^NO3).

Purpose of the Study:

• To develop novel uranyl photocatalysts with enhanced stability and tunable reactivity.
• To investigate the influence of equatorial ligands on the selectivity and efficiency of uranyl-catalyzed C-H functionalization.

Main Methods:

• Synthesis and characterization of uranyl tris(benzoate) complexes (1-R) with tunable equatorial ligands.
• Photocatalytic reactions involving C-H bond functionalization via HAA using the synthesized uranyl complexes.
• Analysis of reaction selectivity and comparison with existing uranyl catalysts and other photoactive oxo complexes.

Main Results:

• Uranyl tris(benzoate) complexes (1-R) exhibit photocatalytic activity for C-H bond functionalization by HAA.
• Ligand framework significantly influences reactivity and selectivity, distinct from U^NO3 or decatungstate.
• Stable U-O bonds facilitate radical acceptor reactions, enabling C-C and C-N bond formation through alkyl radical intermediates.
• Regioselective alkylation and functionalization of diverse substrates were achieved.

Conclusions:

• Modulating equatorial ligands on [UO2]2+ offers a powerful strategy to control photocatalytic C-H bond functionalization.
• Novel uranyl complexes provide a platform for efficient and selective C-H activation and subsequent bond formation.