Site-selective metallation of dicarbene precursors

Abstract

An imidazolium/2-chlorobenzimidazole bis-NHC precursor has been reacted with Ag₂O followed by transmetallation with [AuCl(THT)] to give the Au–NHC complex via metallation of the imidazolium site, while the reaction of the same bis-NHC precursor with [Pd(PPh₃)₄] yields exclusively the azolato complex by oxidative addition of the C2–Cl bond to Pd⁰. Both complexes have been converted into the heterobimetallic Au/Pd-complex by reaction with [Pd(PPh)₃]₄ (for the NHC complex) or Ag₂O/[AuCl(THT)] (for the azolato complex), respectively.