The unsymmetrical tris(imidazolium) salt H-3-1(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.