Metal complexes with di(N-heterocyclic carbene) ligands bearing a rigid ortho-, meta or para-phenylene bridge

Three novel dinuclear bis-dicarbene silver(I) complexes of general formula [Ag-2(Melm-phenylene-Melm)(2)] (PF6)(2) (Im = imidazol-2-ylidene) were synthesized. The corresponding copper(I) and gold(I) complexes were obtained by transmetalation of the di(N-heterocyclic carbene) ligand from the silver(I) species, and both coordination geometry and stoichiometry are maintained for all three group 11 metals as expected. The photophysical properties of the Ag(I) and Au(I) complexes were also investigated and discussed; in particular the most strongly emitting complex was also studied via DFT calculations. In addition, the ruthenium(II) and iridium(III) complexes [RuCl(Melm-(o-phenylene)-Melm)(p-cym)](PF6) and [IrClCp*-(Melm-(o-phenylene)-Melm)](PF6) were prepared and shown to present in these cases a chelating coordination of the di (N-heterocyclic carbene) ligand.