This article is focused on recent developments in main group mediated hydrogenation chemistry and catalysis using "frustrated Lewis pairs" (FLPs). The broading range of substrates and catalyst systems is reviewed and the advances in catalytic reductions and the development of stereoselective, asymmetric reductions made since 2012 is considered.

Acyl(chloro)phosphines RC(O)P(Cl)(t-Bu) have been prepared by formal insertion of tert-butyl phosphinidene (t-Bu–P) from t-BuPA (A = C14H10 or anthracene) into the C–Cl bond of acyl chlorides.

The reactions of the phosphaethynolate anion ([PCO] ) with a range of boranes were explored. BPh and [PCO] form a dimeric anion featuring P-B bonds and is prone to dissociation at room temperature. The more Lewis acidic borane B(C F ) yields a less symmetric dimer of [PCO] with P-B and P-O bonds. Less sterically demanding HB(C F ) and H B(C F ) boranes form a third isomer with [PCO] featuring both boranes bound to the same phosphorus atom. Despite the unexpected thermodynamic preference for P-coordination, computational data illustrate that electronic and steric features impact the binding modes of the resulting dianionic dimers.

The neutral PCO derivative Ph3GePCO undergoes addition of borohydride to generate the anion [Ph3GePC­(H)­OBPh3]−. A subsequent deprotection strategy provides access to the monomethyl and dimethylformyl phosphines, Ph3GeP­(Me)­C­(H)O and Me2PC­(H)­O, respectively. The latter species which is the phosphorus analogue of DMF, was characterized and shown to complex via phosphorus to Ru. A computational study also highlights the similarities and differences between the P- and N-containing molecules.