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 = Rh(III), Ir(III)) to yield heterobimetallic complexes [3] (M = Rh) and [4] (M = Ir), in which the Pd(II) ion is chelated by two ortho N-heterocyclic carbene (NHC) donors while the third NHC donor coordinates to the M(III) center, which orthometalates the central phenyl ring.