Frustrated Lewis Pairs: Metal‐free Hydrogen Activation and More

Abstract Sterically encumbered Lewis acid and Lewis base combinations do not undergo the ubiquitous neutralization reaction to form “classical” Lewis acid/Lewis base adducts. Rather, both the unquenched Lewis acidity and basicity of such sterically “frustrated Lewis pairs (FLPs)” is available to carry out unusual reactions. Typical examples of frustrated Lewis pairs are inter‐ or intramolecular combinations of bulky phosphines or amines with strongly electrophilic RB(C 6 F 5 ) 2 components. Many examples of such frustrated Lewis pairs are able to cleave dihydrogen heterolytically. The resulting H + /H − pairs (stabilized for example, in the form of the respective phosphonium cation/hydridoborate anion salts)…