The Crucial Role of Lewis Basicity of N-Heterocyclic Carbenes in the CO2 Hydroboration Reduction: Comprehensive Insights from Density Functional Theory Calculations and Microkinetic Simulations

Abstract

The hydroboration reduction of CO₂ by HBpin, catalyzed by N-heterocyclic carbene (NHC), has been investigated using density functional theory (DFT) calculations and microkinetic simulations. NHC acts as an effective activator for both CO₂ and HBpin, and thus, NHC and its CO₂ adduct, NHC–CO₂, function as crucial active catalysts in the hydroboration reduction of CO₂. Herein, the preferences of these two active catalysts in the hydroboration of CO₂ have been evaluated, and the catalytic reaction mechanism has been unveiled. A linear relationship between carbene-type catalysts and their chemical reactivities is established to screen highly activated carbene species for the CO₂ hydroboration reduction. It is found that the chemical reactivities of NHCs, including small molecule activation and CO₂ hydroboration reduction, are closely related to their Lewis basicity and global nucleophilicity. In addition, microkinetic simulations have been performed to analyze the influence of initial stoichiometric ratio and temperature on the temporal distribution of various species. The present study suggests a fresh perspective on the application of NHC and its analogues in CO₂ reduction.