1. Unexpected role of two ortho-OH groups for the hydrogenation of CO2 to methanol catalyzed by Fe bipyridinol complexes.
- Author
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Yan, Xiuli, Hao, Yongjing, Zhu, Zheng, Chang, Tao, and Yang, Xinzheng
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HYDROGENATION , *CATALYSTS , *METHANOL , *CARBON dioxide , *HYDROGEN bonding - Abstract
• Density functional theory study of hydrogenation of CO 2 to methanol catalyzed by iron bipyridinol complexes. • An unexpected three-site metal-ligand cooperation (MLC) mechanism for the breaking of C–O and O–H bonds and the formation of O–H...O hydrogen bonds. • The essential role of the bipyridinol ligand with hydroxyl groups for hydrogenation reactions. A density functional theory study of Fe-catalyzed hydrogenation of CO 2 to methanol reveals an unexpected metal–ligand cooperation mechanism with two ortho -OH groups play key roles for the breaking of C–O and O–H bonds and formation of O–H...O hydrogen bonds. The formation of methanediol via hydride transfer from Fe to formic acid (4′ → TS 6,7) is the rate-determining step with a total barrier of 30.8 kcal mol−1 in free energy. Furthermore, by replacing the two meta (R 1) and two para (R 2) hydrogen atoms in the bipyridinol ligand and the coordinated CN and CO with different functional groups, we built a series of stable iron complexes and computationally predicted their catalytic activities for hydrogenation of CO 2 to methanol. Among all newly proposed iron complexes, 1t and 1u are promising catalyst candidates for hydrogenation of CO 2 to methanol with rather low total free energy barriers of 26.6 and 28.8 kcal mol−1, respectively. The electrostatic potential map analysis indicates that stronger electron donating ligands on iron may lead to higher catalytic activities. DFT calculations reveal an unexpected metal–ligand cooperation mechanism with two ortho -OH groups play key roles for the breaking of C–O and O–H bonds and formation of O–H...O hydrogen bonds. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2022
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