Hydrogenation of Carbon Dioxide to Methanol Catalyzed by Iron, Cobalt, and Manganese Cyclopentadienone Complexes: Mechanistic Insights and Computational Design

摘要

Density functional theory study of the hydrogenation of carbon dioxide to methanol catalyzed by iron, cobalt, and manganese cyclopentadienone complexes reveals a selfpromoted mechanism, which features a methanol-or watermolecule-assisted proton transfer for the cleavage of H_2. The total free energy barrier of the formation of methanol from CO_2 and H_2 catalyzed by Kn?lker's iron cyclopentadienone complex, [2,5-(SiMe_3)_2-3,4-(CH_2)_4(η_5-C_4COH)]Fe(CO)_2H, is 26.0 kcalmol-1 in the methanol solvent. We also evaluated the catalytic activities of 8 other experimentally reported iron cyclopentadienone complexes and 37 iron, cobalt, and manganese cyclopentadienone complexes proposed in this study. In general, iron and manganese complexes have relatively higher catalytic activities. Among all calculated complexes, [2,5-(SiMe_3)_2-3,4-CH_3CHSCH_2(η_5-C_4COH)]Fe(CO)_2H (1Fe-Casey-S-CH_3) is the most active one with a total free energy barrier of 25.1 kcalmol-1 in the methanol solvent. Such a low barrier indicates that 1Fe-Casey-S-CH_3 is a very promising low-cost and high efficiency catalyst for the conversion of CO_2 and H_2 to methanol under mild conditions.