Flexible proton-responsive ligand-based Mn(i) complexes for CO₂ hydrogenation: a DFT study.

Area of Science:

• Inorganic Chemistry
• Catalysis
• Sustainable Chemistry

Background:

• Carbon dioxide (CO2) hydrogenation is crucial for sustainable chemical synthesis.
• Base-free catalytic systems are desirable to avoid side reactions and simplify product purification.
• Manganese complexes offer a potentially cost-effective and earth-abundant alternative to precious metal catalysts.

Purpose of the Study:

• To investigate the role of flexible proton-responsive ligands in base-free CO2 hydrogenation.
• To explore manganese(I) complexes featuring N^N-bidentate ligands for catalytic CO2 reduction.
• To understand the mechanism by which these ligands influence the H2 activation step.

Main Methods:

• Synthesis and characterization of novel manganese(I) complexes with proton-responsive N^N-bidentate ligands.
• Computational studies, including DFT calculations, to determine reaction free energy barriers.
• Analysis of the electronic and structural effects of the ligands on dihydrogen activation.

Main Results:

• Proton-responsive ligands significantly enhance the efficiency of base-free CO2 hydrogenation.
• Calculated activation energy barriers for heterolytic H2 cleavage are remarkably low (around 3 kcal mol-1).
• Flexible ligands strengthen dihydrogen (H2) bonding, facilitating H2 cleavage.

Conclusions:

• Flexible proton-responsive ligands are critical for enabling efficient base-free CO2 hydrogenation.
• The studied manganese complexes demonstrate potential as catalysts for sustainable CO2 conversion.
• Ligand design is a key strategy for optimizing catalytic activity in hydrogenation reactions.