The role of cations in the interactions between anionic N-heterocycles and SO(2)

Our study shows that cation plays a more important role in the interactions between anionic N-heterocycles and SO(2) than in the NHC-CO(2) case. The adducts of NHC, SO(2) and cation often exhibit multiple stable configurations with close energies rather than the only reported “CO(2)-sandwiched” planar NHC-CO(2)-cation structure. The structural diversity makes the models omitting cation inappropriate for predicting the SO(2) capture products, which also leads to less clear trends of the cation effects than those observed in the CO(2) case. The detailed cation effects are discussed in the text.