Highly Dispersed Pd Species Active in the Suzuki-Miyaura Reaction

Structures of Pd/zeolites immersed in solvents were measured by in situ X-ray absorption fine structure (XAFS). Systematic studies revealed that the selection of an appropriate support (USY-zeolite), thermal treatment temperature of USY, solvent (o-xylene), H-2 partial pressure (6%), and the use of a Pd amine complex affect the structure of Pd. As a result, we found that monomeric Pd can be obtained in the USY support with H-2 bubbling in o-xylene. The structural properties of Pd correlate well with its catalytic performance in the Suzuki-Miyaura coupling reactions; a very high TON of up to 11000 000 was obtained over the monomeric Pd.