Detailed Mechanism for Hiyama Coupling Reaction in Water Catalyzed by Linear Polystyrene-Stabilized PdO Nanoparticles

The catalytic cycle of the Hiyama coupling reaction in water catalyzed by linear polystyrene-stabilized PdO nanoparticles (PS-PdONPs) was investigated. The formation of 4-methylbiphenyl was confirmed from the reaction of 4-bromotoluene with the catalyst recovered from the reaction of PS-PdONPs with trimethoxyphenylsilane. The catalytic activity of PS-PdONPs significantly diminished upon addition of NaI or poly(4-vinylpyridine). The Hiyama coupling reaction using PS-PdONPs as a catalyst proceeds through a different mechanism from the commonly accepted one that starts from the oxidative addition of an aryl halide to a Pe((0)) species.