Synthesis of NHC Complexes with an N‐(2‐Oxopropyl) Group

Abstract

Dedicated to Prof. Wolfgang Kaim on the Occasion of his 70th BirthdayThe unsymmetrically N,N ,N'-picolylbenzimidazolium chloride (H-1)Cl, featuring an N-protecting group has been prepared. Reaction of (H-1)Cl with Ag 2 O followed by transmetallation of the NHC to [MCl 2 (Cp*)] 2 (M = Rh, Ir) yielded complexes [MCl(Cp*)(k 2 -1)]Cl (M = Rh, [2]Cl; M = Ir, [3]Cl) with a chelating coordinated C NHĈ N pyridine ligand. Anion exchange gave complexes [2]BF 4 (M = Rh) and [3]BF 4 (M = Ir). Transmetallation of the NHC ligand from silver(I) to gold(I) gave the mononuclear complex [AuCl(1)] [4] bearing a monodentate, N-picoly funtionalized NHC ligand. Complex [4] reacts with AgBF 4 to yield the dinuclear complex [5](BF 4 ) 2 featuring two bridging μ 2 -C NHC^Npyridine ligands. The molecular structures of [2]BF 4 • CH 2 Cl 2 and [3]BF 4 • CH 2 Cl 2 have been determined by X-ray diffraction studies.