Homogeneous Catalytic CO₂ Hydrogenation by [Fe]-Hydrogenase Bioinspired Complexes: A Computational Study

Area of Science:

• Computational chemistry and catalysis
• Organometallic chemistry
• Sustainable energy research

Background:

• The [Fe]-hydrogenase active site serves as a biological inspiration for artificial catalysts.
• Efficient and sustainable methods for CO2 hydrogenation to formic acid are crucial for carbon utilization.
• Developing base- and additive-free catalytic systems remains a significant challenge.

Purpose of the Study:

• To computationally design and evaluate novel iron catalysts for CO2 hydrogenation.
• To elucidate the catalytic mechanism and identify key intermediates and transition states.
• To compare the catalytic performance of different iron complexes with varying ligand structures.

Main Methods:

• Density-based functional theory (DFT) calculations at the M06-L/def2-TZVP level.
• High-level coupled-cluster calculations (DLPNO-CCSD(T)/CBS) for accurate energy evaluations.
• Quasi-harmonic corrections applied to mimic experimental conditions.

Main Results:

• Four distinct iron catalyst structures were proposed, inspired by the [Fe]-hydrogenase active site.
• Detailed electronic structure calculations identified reaction intermediates and transition states.
• Turnover frequencies (TOFs) indicated that iron catalysts with tridentate phosphine pincer ligands (D(1) and C(1)) exhibit superior performance.

Conclusions:

• Iron complexes featuring tridentate phosphine pincer ligands are highly promising for CO2 hydrogenation.
• The developed catalysts enable the direct conversion of CO2 to formic acid without bases or additives.
• These findings offer a new avenue for designing efficient and sustainable catalysts for CO2 valorization.