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

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• N-heterocyclic carbenes (NHCs) are versatile ligands in organometallic chemistry.
• Xanthene-based ligands offer unique structural and electronic properties.
• Bimetallic complexes can exhibit synergistic effects and novel reactivity.

Purpose of the Study:

• To synthesize and characterize novel bimetallic NHC-metal complexes.
• To investigate the coordination behavior of NHC ligands attached to a xanthene scaffold.
• To explore the potential of these complexes in catalysis or materials science.

Main Methods:

• Synthesis of xanthene-functionalized NHC precursors.
• Coordination of NHC ligands with various metal precursors (e.g., Rh, Ir, Au, Ag, Cu, Pd).
• Characterization of the resulting bimetallic complexes using spectroscopic and analytical techniques.

Main Results:

• Successful synthesis of several xanthene-((NHC)ML)2 bimetallic complexes.
• Confirmation of the coordination mode where each NHC unit binds one metal center.
• Demonstration that chelation of a single metal by two NHC units is sterically hindered.
• Investigation of complexes with ML = RhCl(cod), IrCl(cod), RhCl(CO)2, IrCl(CO)2, AuCl, AgCl, CuCl, and Pd(allyl)Cl.

Conclusions:

• The study presents a new class of bimetallic NHC-metal complexes based on a xanthene framework.
• The synthetic strategy allows for controlled coordination of two separate metal centers by the bimetallic ligand.
• These complexes represent promising platforms for further exploration in catalysis and coordination chemistry.