Possible Synthetic Approaches for Heterobimetallic Complexes by Using NHC/NHC Heteroditopic Carbene Ligands.

The synthesis of heterobimetallic complexes remains a synthetic challenge in the field of organometallic chemistry. A possible approach in this regard might be the use of a bidentate heteroditopic bis(carbene) ligand that combines an imidazol-2-ylidene (NHC) with a 1,2,3-triazol-5-ylidene (NHC) connected by an organic spacer. The optimized strategy to heterobimetallic complexes with this type of ligand involves a 3-step procedure: (i) Coordination of the NHC, functionalized with a 1,2,3-triazole ring, to a metal center; (ii) formation of the triazolium ring by alkylation of the triazole N-3; (iii) deprotonation of the NHC precursor and coordination of the second metal center.