Reaction Mechanism of Epoxide Cycloaddition to CO2 Catalyzed by Salen‑M (M = Co, Al, Zn)

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 118; no. 39; pp. 9239 - 9243
• Main Authors: Wang, Ting-Ting, Xie, Yong, Deng, Wei-Qiao
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02.10.2014
• ISSN: 1089-5639; 1520-5215; 1520-5215
• DOI: 10.1021/jp506124h

We propose a catalytic mechanism for the cycloaddition of epoxide to carbon dioxide catalyzed by salen-M (M = Co, Zn, Al) based on density functional theory calculations. The catalytic reaction follows a single-site mechanism rather than a bimetallic-site mechanism, which includes four steps: epoxide adsorption by salen-M, ring opening of epoxide, CO2 insertion, and intramolecular rearrangement. Our calculation results showed that the highest reaction barrier for salen-Co catalyst is only 9.94 kcal/mol, which is lower than that of salen-Al (14.38 kcal/mol) and salen-Zn (13.05 kcal/mol). The results indicate that the reaction catalyzed by salen-Al, salen-Co, or salen-Zn can occur at room temperature and atmospheric pressure, which is in agreement with experimental results. The mechanism can be used for the design of a novel catalyst for this reaction.