Supported Pd Nanoparticles with a Metallic and Oxidized Multisite for Sustainable Suzuki-Miyaura-Type C-H Arylation

Here, we demonstrated that γ-Al₂O₃-supported palladium nanoparticles containing dominant metallic-state Pd sites and charged Pd (Pd²⁺ and Pd¹⁺) sites are a highly active, selective, and stable heterogeneous catalyst for a variety of Suzuki-Miyaura-type C(sp³)-H or C(sp²)-H arylation reactions, resulting in a high cumulative turnover number (TON) of 226 after 6 runs. Multi-technique characterization data, including X-ray absorption fine structure (XAFS) analyses, showed that both the strong metal-support interaction (SMSI) with Pd-O coordination and the fitting increase of metal-metal bonds after reaction efficiently limit Pd leaching and Pd⁰ aggregates. The support concerted metalation-deprotonation (SCMD) effect of Pd/γ-Al₂O₃ is more favorable for the proceeding of the Pd²⁺/Pd⁰ catalytic cycle at the microenvironment. This study sheds light on a new approach for heterogenization of homogeneous palladium catalysts in inert C-H bond activation reactions.