The activity and reversibility of intramolecular B/N Frustrated Lewis Pairs in the hydrogenation

Abstract

Frustrated Lewis Pairs (FLPs) as the zwitter compound is not only an effective catalyst in the hydrogenation process, but also a potential excellent hydrogen-storage material. Therefore, the activity and the reversibility of the ab-/desorbing hydrogen process of FLPs are generally determined by the acidity of the Lewis acid (LA) and the alkalinity of the Lewis base (LB). Herein, we learn three classic B/N intramolecular FLPs composed by Pier's acid and N-heterocyclic groups to evaluate the relationship between the energy of deformation of LA/LB and the reactivity of FLPs in the hydrogenation. The acidity is determined by the energy of structural transformation in activating hydrogen, while the alkalinity of LB is determined by the electron density of connected groups. Different from the traditional point that the strong LA and LB form a perfect FLPs, the excellent FLPs appears reversibility and fast reaction rate in the hydrogenation when it composed by a strong LA (72.97 = GA ≤ 120.15 kcal/mol) and a relative weak LB (GB ≥ 155.28 kcal/mol). The results help us to establish a quantitative relationship between the deformation energy of FLPs and the reversibility/activity in the Ab-/Desorbing hydrogen process of the intramolecular B/N FLPs.