Borane Derivatives of Five-Membered N-heterocyclic Rings As Frustrated Lewis Pairs: Activation of CO 2

The reaction of seventeen borane derivatives of five-membered N-heterocyclic rings (BNHRs) with CO 2 has been studied by means of DFT calculations. Several non-covalent complexes between the BNHRs and CO 2 which evolve through a TS in a single adduct for each BNHR have been identified. The calculated IRC of the TS has allowed to identify the non-covalent complex involved in the reaction in each case. The stationary points of the reactions have been analyzed with the distortion/interaction partition model. In addition, empirical models have been attempted to correlate the acid (fluoride ion affinity) and basic (proton affinity) properties of the isolated BNHR with the TS barriers and adduct energies. The energetics of the reactions are influenced by the number of nitrogen atoms in the ring.