Unsymmetrical Imidazopyrimidine-Based Ligand and Bimetallic Complexes

Area of Science:

• Coordination Chemistry
• Catalysis
• Organic Synthesis

Background:

• Bimetallic catalysts are crucial for various chemical transformations.
• Development of versatile binucleating ligands is essential for advancing bimetallic catalyst design.
• Existing ligands may lack the electronic and structural diversity needed for novel catalyst architectures.

Purpose of the Study:

• To synthesize a novel unsymmetric binucleating ligand, 2,7-di(pyridin-2-yl)imidazo[1,2-a]pyrimidine (dpip).
• To demonstrate the utility of dpip as a scaffold for constructing diverse bimetallic complexes.
• To investigate the electronic properties and coordination behavior of dpip-based complexes using computational methods.

Main Methods:

• Multigram scale synthesis of the dpip ligand in four steps.
• One-step synthesis of dicopper, dipalladium, and dinickel bimetallic complexes.
• Characterization using spectroscopic methods and X-ray crystallography.
• Quantum chemical calculations including Natural Bonding Orbital (NBO) and Mayer Bond Order (MBO) analyses.

Main Results:

• The dpip ligand was synthesized in 54% overall yield.
• Bimetallic complexes of copper, palladium, and nickel were formed in high yields (79-92%).
• X-ray crystallography confirmed metal-metal distances and revealed structural details.
• Computational analyses indicated stronger metal coordination by dpip compared to 1,8-naphthyridine.

Conclusions:

• The unsymmetric dpip ligand is a versatile scaffold for synthesizing diverse bimetallic complexes.
• dpip exhibits enhanced metal-coordinating ability, beneficial for catalyst development.
• This work provides a new tool for designing advanced bimetallic catalysts with tailored properties.