Acridine PNP-Pincer Ligands Enabling Transition Metal-Catalyzed Photoreactions

Transition metal-catalyzed reactions are developed togetherwithligands. While transition metal-catalyzed photoreactions have beenextensively reported in recent years, the development of ligands forphotoreactions is limited to only a few cases. Therefore, establishingligands that shed light on transition metal-catalyzed photoreactionsis an important research goal. We successfully synthesized four acridine-containingPNP-pincer ligands and formed transition metal complexes with Ni,Pd, Pt, Cu, and Co. We found that the platinum complex induced photoreactionsof olefins under visible light irradiation: transfer hydrogenation,which required only a stoichiometric amount of hydrogen source, andhydroxy/alkoxy alkylation of olefins. These reactions did not proceedwith existing well-known ligands, demonstrating that the developmentof photoreaction-oriented ligands reveals unknown reactivities oftransition metals.

Automated summary

Transition metal-catalyzed photoreactions have been extensively reported, but the development of ligands for these reactions is limited. This study successfully synthesized acridine-containing PNP-pincer ligands and found that the platinum complex induced photoreactions of olefins under visible light irradiation. These reactions revealed unknown reactivities of transition metals that could not be achieved with existing well-known ligands.