Mechanistic Insight into the Hydrogen Activation by Frustrated Lewis Pairs

Abstract

The combination of a Lewis acid (LA) and a Lewis base (LB) in such a way that they are prevented from forming a classical LA–LB adduct by means of steric hindrance or thermal hindrance is called a Frustrated Lewis Pair (FLP). FLPs have been shown to function as metal-free catalysts for small molecule activation and conversion. In this chapter, we review theoretical results from combined quantum mechanical calculations and first-principles (DFT) molecular dynamics/metadynamics simulations with the aim of understanding the mechanistic aspects of FLP reactivity. Our results are contextualized with the recently published work from other researchers. The mechanisms of H2 activation by both inter- and intramolecular FLPs are examined and the impact of water on FLP reactivity is discussed. Furthermore, the possibility of alternative mechanisms of H2 activation by activated carbonyl carbon is presented. Carbonyl carbon is activated (polarized) by complexation of the C = O group to a Lewis/Bronsted acid or formation of an H-bond with an H-bond donor in solution. Finally, an overview of applications of Lewis pair-functionalized metal–organic frameworks (MOFs) for H2 activation is given.