Practical Ligand-Enabled N₂ Adsorption of Rhenium(I) Carbonyl Complexes Based on Meridionally Coordinated Terpyridine

Area of Science:

• Inorganic Chemistry
• Catalysis
• Materials Science

Background:

• Efficient nitrogen (N2) adsorption on metal sites is crucial for N2 activation under mild conditions.
• Understanding N2 adsorption selectivity and environmental factors is vital for catalyst design and mechanistic elucidation.

Purpose of the Study:

• To synthesize and investigate the N2 reactivity of a mer, cis-Re(tpy)(CO)2Cl complex.
• To elucidate the factors influencing N2 adsorption and activation on rhenium-terpyridine complexes.

Main Methods:

• Synthesis of the mer, cis-Re(tpy)(CO)2Cl complex.
• Electrospray ionization mass spectrometry (ESI-MS) to generate and study reactive species.
• Density functional theory (DFT) calculations to analyze electronic and steric effects.

Main Results:

• ESI-MS revealed the N2 adsorption reactivity order: [Re(tpy)]+ > [Re(tpy)(CO)]+ >> [Re(tpy)(CO)2]+ (inert).
• DFT calculations confirmed π back-donation between Re and N2.
• Reactivity decrease is attributed to electron depletion and steric hindrance from CO ligands.

Conclusions:

• CO ligands decrease N2 adsorption reactivity by reducing Re's π back-donation capacity and causing steric hindrance.
• This research provides insights into ligand-metal synergistic effects for designing N2 adsorption and activation systems.