Excess-electron-induced C–C bond formation in transformation of carbon dioxide

Abstract

This study presents a new fixation method of CO₂ through excess-electron-induced C–C bond formation using quantum chemical method. Because of active CO₂⁻˙ with a distinct radical character at the carbon center, two divalent anion complexes [O₂C–C₆H₆–CO₂]²⁻ (cis-II and trans-II) are obtained via C–C bond formation between the carbon atom of C₆H₆ and the carbon atom of CO₂ in the process of CO₂⁻˙ radical attacking on benzene molecule. Furthermore, the transformations of cis-II and trans-II are predicted. We found that the more favorable transformation is for cis-II. It can produce terephthalic and one H₂ molecule via two H-atom elimination with the energy barrier of 35.70 kcal mol⁻¹. Furthermore, we found that the formed hydrogen bond complex CO₂–HCN did not reduce the energy barrier; however, it could reduce the energy of the transition state with respect to that of the reactant, due to it dispersing the charge of benzene ring.