Mechanistic Studies on Photoinduced Catalytic Olefin Migration Reactions at the Pd(II) Centers of a Porous Crystal, Metal-Macrocycle Framework.

Porous crystals with well-defined active metal centers on the pore surface have high potential as heterogeneous metal catalysts. We have recently demonstrated that a porous molecular crystal, metal-macrocycle framework (MMF), catalyzes olefin migration reactions by photoactivation of its Pd II Cl 2  moieties exposed on the crystalline channel surface. Herein we report a mechanistic study of the photoinduced olefin migration reactions at the Pd II  active centers of MMF. Several experiments, including a deuterium scrambling study, revealed that olefin migration is catalyzed  via  an alkyl mechanism by  in situ  generated Pd-H species on the channel surface during photoirradiation. This proposed mechanism was further supported by DFT and ONIOM calculations.