Heterobimetallic Carbene Complexes by a Single-Step Site-Selective Metalation of a Tricarbene Ligand

The unsymmetrical tris­(imidazolium) salt H3-1(Br)3, featuring a 1,2,4-substitution pattern of the central phenyl ring, after triple imidazolium C2 deprotonation reacts in a one-pot reaction with Pd­(OAc)2 and [M­(Cp*)­(Cl)2]2 (M = RhIII, IrIII) to yield heterobimetallic complexes [3] (M = Rh) and [4] (M = Ir), in which the PdII ion is chelated by two ortho N-heterocyclic carbene (NHC) donors while the third NHC donor coordinates to the MIII center, which orthometalates the central phenyl ring.