Suzuki Coupling Reactions Catalyzed by PdO Dispersed on Dealuminated Y Zeolite in Air under Ambient Conditions.

Suzuki coupling reactions are performed using PdO loaded on dealuminated Y (USY) zeolite. The reaction between bromobenzene and phenylboronic acid is complete in 15 min at room temperature in air, with a turnover number of 1300. The reaction can be repeated at least five times by using 1 wt % Pd. Inductively coupled plasma analysis does not reveal the dissolution of Pd from products, even if the reaction is repeated up to four times. Pd K-edge extended X-ray absorption fine structure analysis reveals the presence of molecular-like PdO and a mixture of Pd(0) -PdO before and after the reaction, respectively. This is probably because Pd stabilized by Al sites is present at the II sites of the Y-type zeolite, as estimated using first-principles calculations. Conversely, Pd species change to PdO clusters after repeated reactions in air using the thermally treated sample.