ABSTRACT
Bis-NHC precursors composed of an azolium and a 2-halogenoazole group connected by different linkers have been site-selectively metallated to give heterobimetallic complexes from a single-frame bis-NHC ligand. The azolium group reacts with a base and oxidized metal centers to give NHC complexes with no participation of the halogenoazole, while the halogenoazole reacts in an oxidative addition with low-valent transition metals to give azolato complexes with no participation of the azolium group.
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.
