Factors Affecting the Oxidative Addition of Aryl Electrophiles to 1,1‘-Bis(diphenylphosphino)ferrocenepalladium(η²-methyl acrylate), an Isolable Pd[0] Alkene Complex

Abstract

The title complex 3 has been synthesized and characterized by X-ray crystallography. It undergoes oxidative addition with aryl triflates and iodides by a nondissociative mechanism in THF. The Heck addition product methyl cinnamate was detected at traces from the reaction with phenyl triflate, and from iodobenzene the direct oxidative addition product was characterized. The addition of halides or acetate salts to the system led to modest effects on the rate of oxidative addition of aryl triflates, but resulted in neutral arylpalladium(II) complexes. Addition of lithium or europium salts enhanced the reaction rate, the effect being most pronounced with Eu(OTf) 3, possibly through promotion of a competing dissociative pathway.