Visible-Light-Responsive Tetranuclear Ir-Based Polyoxometalates Achieve Photocatalytic Baeyer–Villiger Oxidation of Ketones

Synthesizing efficient photocatalysts with a broad-spectrum response is crucial for improving solar energy utilization. In this work, we have constructed two examples of tetrameric Ir-based polyoxometalates by introducing an Ir ion. The introduction of Ir ions lowers the band gap energy, and the light absorption range is extended into the visible region. Both displayed satisfactory reactivity for the visible-light-catalyzed Baeyer-Villiger reaction of cyclohexanone, especially compound 1, which reacted up to 95.1% yield for 3 h with TON and TOF values of 951 and 510 h-1, respectively. Meanwhile, 1 also presents excellent cyclic and structural stability, and the yield can still reach 92.2% after five cyclic reactions.