Regioselective Synthesis and Characterization of Multinuclear Convex-Bound Ruthenium-[n]Cycloparaphenylene (n = 5 and...

Area of Science:

• Organometallic Chemistry
• Supramolecular Chemistry
• Coordination Chemistry

Background:

• Cycloparaphenylenes (CPPs) are macrocyclic aromatic hydrocarbons with unique structural and electronic properties.
• Ruthenium complexes are widely studied for their catalytic and photophysical applications.
• Synthesizing multinuclear metal complexes with macrocyclic ligands presents challenges in controlling coordination modes.

Purpose of the Study:

• To synthesize and characterize novel mono- and multinuclear ruthenium complexes with [5] and [6]cycloparaphenylenes ([5]CPP and [6]CPP).
• To investigate the selective coordination behavior of ruthenium onto the CPP macrocycle.
• To elucidate the binding mode and structural features of the resulting ruthenium-CPP complexes.

Main Methods:

• Ligand exchange reaction using a cationic ruthenium precursor, [(Cp)Ru(CH3CN)3](PF6).
• Synthesis of mono- and multinuclear complexes with varying CPP sizes.
• Single-crystal X-ray diffraction analysis to determine the solid-state structure.

Main Results:

• Mono- and multinuclear ruthenium complexes with [5] and [6]CPPs were obtained in excellent yields.
• Ruthenium selectively coordinated to alternate paraphenylene units in multinuclear complexes.
• Bis- and tris-ruthenium complexes were formed for [5]CPP and [6]CPP, respectively.
• X-ray crystallography confirmed η(6)-hapticity of ruthenium coordination on the convex surface of CPPs.

Conclusions:

• The study successfully demonstrates the controlled synthesis of ruthenium complexes with CPPs.
• Selective coordination of ruthenium to alternate units of CPPs is achievable.
• The findings provide insights into the coordination chemistry of ruthenium with macrocyclic aromatic systems.