Heterogenized PCP Pd Pincer Complexes for the Arylation of Styrenes With Iodonium Salts

ABSTRACT Phosphine‐based (PCP) palladium pincer complexes, renowned for their tunable steric and electronic properties, are effective homogeneous catalysts but are prone to decomposition under the mild reductive conditions typical of cross‐coupling reactions. This decomposition can generate a mixture of metal complexes and nanoparticles, complicating the rationalization of the catalytic outcome. Herein, a phosphinite Pd‐POCOP‐Cl complex was used to synthesize silica‐supported heterogenized pincer complexes for the model arylation of p ‐bromostyrene with diphenyliodonium triflate, a reaction previously studied for its homogeneous counterpart in a proposed Pd(II)/Pd(IV) cycle but underexplored in heterogeneous catalysis. The heterogenization on SiO 2 produced surface complexes that evolved under reaction conditions, exhibiting a 15‐fold higher catalytic activity than the homogeneous Pd‐POCOP‐Cl complex under similar conditions. This enhanced performance originated from the decomposition of the surface complexes, even in non‐reductive conditions, leading to Pd leaching into the solution and forming an inactive Pd(II) species grafted onto the solid support. This transformation was facilitated by surface hydroxyl groups on SiO 2 , ultimately generating soluble Pd(0) species that retained phosphorus coordination before agglomerating into nanoparticles.