Theoretical prediction on CO insertion reactions through the anionic complex [ClMg(η2-O2C]− as a catalyst

Abstract

The mechanisms of the reaction of CO inserting into the CH bond of furane/thiofuran through the anionic magnesium–CO2 complex [ClMg(η2-O2C)]− as a reaction catalyst are investigated using the second-order Møller-Plesset (MP2), and the polarized continuum model (PCM) is applied to simulate the solvent effects. Calculated results show that the insertion reaction route includes three steps: (i) the dehydrogenation of furane/thiofuran through the capturing of the anion complex [ClMg(η2-O2C)]− with strong carbene character, results in an intermediate I, (ii) the addition of CO via the CC bond formation between the carbon atom of I and the carbon atom of CO through the partial negative charge transfer into the π∗ orbital of CO, forms an anion species III, and (iii) H abstraction from the neutral complex [ClMg(η2-O2CH)]0 produces the aldehyde product. We find that the reactions of CO inserting into the CH bond of furane/thiofuran is an endothermic process, and the H abstraction to form aldehyde species (corresponding transition states TS3) is the rate-determining step. Meanwhile, solvent effect is important for the CO insertion reaction, for example, the barrier of TS3 in THF solvent is lower by 5kcal/mol than corresponding that in acetone solvent. We expected that the understanding of the insertion reaction can provide valuable insights into related reactions.