Palladium(II) complexes of a bis-2-aminobiphenyl N-heterocyclic carbene: Synthesis, structural studies and catalytic activity

A new imidazolinium [(SIBiphen)H](BF4) was synthesized in three steps from 2-aminobiphenyl. The reaction of the salt with Pd(OAc)2, NaI and t-BuOK gave a dimeric Pd(II) complex [(SIBiphen)PdI2]2, which was analyzed by an X-ray diffraction study. The reaction of [Pd(allyl)Cl]2, the imidazolinium salt and t-BuOK in THF at −78 °C gave the monomeric Pd complex, in which the N-heterocyclic carbene was bound to the metal centre, as confirmed by a single-crystal X-ray diffraction study. A preliminary catalytic study showed that these new systems were moderately active in the Suzuki–Miyaura coupling of aryl halides.