Bi- and trimetallic complexes with macrocyclic xanthene-4,5-diNHC ligands.

Three different types of bimetallic NHC-metal complexes were synthesized, whose NHC units are attached at the 4,5-positions of xanthene. The NHC units are in close proximity and are designed such that each carbene coordinates one ML unit, while the chelation of one metal by two NHC is not possible. Several xanthene-((NHC)ML) 2 complexes with ML = RhCl(cod), IrCl(cod), RhCl(CO) 2 , IrCl(CO) 2 , AuCl, AgCl, CuCl and Pd(allyl)Cl were synthesized and investigated.