DFT Benchmarking for [Fe^II]‑(Alkyl/Alkylidene/Acetylide) Complexes

Area of Science:

• Organometallic chemistry
• Computational chemistry
• Catalysis

Background:

• Earth-abundant metal catalysis, particularly iron, is increasingly important.
• Accurate computational methods are crucial for understanding and designing iron catalysts.

Purpose of the Study:

• To comprehensively evaluate exchange-correlation functionals (XCFs) for organometallic iron(II) complexes.
• To determine which XCFs best reproduce experimental geometry, spin-state, and reactivity.
• To assess XCF performance in predicting stereoselectivity for cyclopropanation reactions.

Main Methods:

• Optimization of organometallic Fe(II) complexes with alkyl, alkylidene, and acetylide ligands using twelve different XCFs.
• Comparison of calculated geometries and spin-states with experimental data.
• Evaluation of XCFs' ability to predict experimental stereoselectivity in cyclopropanation.

Main Results:

• B3LYP* and r2-SCAN demonstrated the highest accuracy in reproducing experimental geometries and ground spin-states.
• These functionals also showed superior performance in replicating experimental stereoselectivity for the cyclopropanation reaction.
• Significant variations in accuracy were observed among the twelve evaluated XCFs.

Conclusions:

• B3LYP* and r2-SCAN are recommended as reliable XCFs for studying organometallic iron(II) complexes.
• These findings aid in the computational design of more efficient and selective iron-based catalysts.
• The study highlights the importance of careful functional selection in computational organometallic chemistry.