Photohemilabile PSP-Rhodium Pincer Catalysts for Dehydrogenative C-H Bond Activation of Arenes

Hemilabile ligands have been widely utilized for transition metal catalysis, but hemilability upon excitation, termed as "photohemilability", is still elusive despite the recent progress of organometallic photocatalysis. In this study, it was discovered that Thioxantphos-based PSP-Rh pincer complexes undergo dehydrogenative C-H bond activation of arenes under irradiation with visible light. Theoretical calculations indicate that a transient photodissociation of the strong S-Rh bond brought about by d-d excitation on Rh is the key to realize oxidative addition of arenes to the Rh(I) center, which can be regarded as a photohemilabile behavior. This C-H bond activation process was successfully applied to visible light-driven C-H borylation of simple arenes.