Frustrated Lewis Pairs

Abstract

The articulation of the notion of "frustrated Lewis pairs" (FLPs), which emerged from the discovery that H2 can be reversibly activated by combinations of sterically encumbered Lewis acids and bases, has prompted a great deal of recent activity. Perhaps the most remarkable consequence has been the development of FLP catalysts for the hydrogenation of a range of organic substrates. In the past 9 years, the substrate scope has evolved from bulky polar species to include a wide range of unsaturated organic molecules. In addition, effective stereoselective metal-free hydrogenation catalysts have begun to emerge. The mechanism of this activation of H2 has been explored, and the nature and range of Lewis acid/base combinations capable of effecting such activation have also expanded to include a variety of non-metal species. The reactivity of FLPs with a variety of other small molecules, including olefins, alkynes, and a range of element oxides, has also been developed. Although much of this latter chemistry has uncovered unique stoichiometric transformations, metal-free catalytic hydroamination, CO2 reduction chemistry, and applications in polymerization have also been achieved. The concept is also beginning to find applications in bioinorganic and materials chemistry as well as heterogeneous catalysis. This Perspective highlights many of these developments and discusses the relationship between FLPs and established chemistry. Some of the directions and developments that are likely to emerge from FLP chemistry in the future are also presented.

The Carbon Dioxide Molecule and the Effects of Its Interaction with Electrophiles and Nucleophiles

“…For instance, the components of the couple t-Bu 3 P/B(C 6 F 5 ) 3 pair add to CO 2 at ambient temperature in bromobenzene with P-C and O-B bond formation, yielding the product t-Bu 3 P-C(O)O-B(C 6 F 5 ) 3 (Scheme 3) [96,97]. An analogous behavior was also observed with the intramolecular frustrated Lewis pair (C 6 H 2 Me 3 ) 2 PCH 2 CH 2 B(C 6 F 5 ) 2 .…”

Design principles in frustrated Lewis pair catalysis for the functionalization of carbon dioxide and heterocycles

“…Although some previous observations already suggested that cooperativity between Lewis pairs could promote metal-free transformations, notably for hydrosilylation [7], it is the use of FLPs for molecular hydrogen activation that led to a surge in research in this field [8][9]. Since, FLPs have been shown to activate many small molecules in addition to being active catalysts in reductive transformations [10][11][12]. The activation of substrates like H2 by transition metal complexes occurs generally by the transfer of electrons from the bond to be cleaved to the LUMO of the metal complex while electrons from the HOMO, either associated with the d orbitals or a ligand in the coordination sphere, are transferred to the anti-bonding orbital (Scheme 1A).…”

Solid frustrated-Lewis-pair catalysts constructed by regulations on surface defects of porous nanorods of CeO2

“…Hydrogen activation by either transition metal complexes or metal-based heterogeneous catalysts have been well developed and successfully applied for various reactions4. Recently, frustrated Lewis pairs (FLPs), Lewis acids and bases that are sterically prevented from interaction to form Lewis acid–base adjuncts, can efficiently and cooperatively activate many small molecules (for example, H 2 , CO 2 , and NO) and even strong C–H bond for important catalytic reactions including hydrogenation, hydroamination and carbon dioxide reduction5678910111213141516171819202122232425.…”