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

Given the growing significance of earth-abundant organometallic catalysis, especially with iron, this study provides a comprehensive evaluation of the most effective exchange-correlation functionals (XCFs) for accurately reproducing the experimental geometry, ground spin-state, and reactivity of organometallic Fe^II complexes bearing alkyl, alkylidene, or acetylide ligands. We optimized these complexes in various spin-states using twelve different XCFs and compared the results with experimental data. Subsequently, we analyzed the optimized geometries of the most stable spin-states against the experimental structures. Finally, we evaluated the ability of the XCFs to replicate the experimental stereoselectivity of the cyclopropanation reaction. Our results indicate that among the functionals evalueted, B3LYP* and r²-SCAN are the XCFs that most effectively reproduce the experimental observations considered for the systems evaluated in this work.