The dicationic imidazolium-phosphonium salt [(SIMes)PFPh2][B(C6F5)4]2 has been prepared and shown to exhibit remarkable Lewis acidity in stoichiometric reactions and acting as an effective Lewis acid catalyst for the hydrodefluorination of fluoroalkanes and the hydrosilylation of olefins.

Ketones are efficiently deoxygenated in the presence of silane using highly electrophilic phosphonium cation (EPC) salts as catalysts, thus affording the corresponding alkane and siloxane. The influence of distinct substitution patterns on the catalytic effectiveness of several EPCs was evaluated. The deoxygenation mechanism was probed by DFT methods.

The hydrosilylation/reduction of tertiary and secondary phosphine oxides to phosphines is catalyzed by B­(C6F5)3 or electrophilic fluorophosphonium cations (EPCs). B­(C6F5)3 is an effective catalyst for phosphine oxide reduction using (EtO)3SiH, PhSiH3, and Ph2SiH2 at elevated temperature (105 °C), while EPCs effect the same reduction at significantly lower temperature with PhSiH3 as reducing agent, allowing for good functional-group tolerance.

Molecular compounds featuring nitrogen atoms are typically regarded as Lewis bases and are extensively employed as donor ligands in coordination chemistry or as nucleophiles in organic chemistry.B yc ontrast, electrophilic nitrogencontaining compounds are muchr arer.N itrenium cations are an ew family of nitrogen-based Lewis acids,t he reactivity of which remains largely unexplored. In this work, nitrenium ions are explored as catalysts in five organic transformations.These reactions are the first examples of Lewis acid catalysis employing nitrogen as the site of substrate activation. Moreover,these compounds are readily accessed from commercially available reagents and exhibit remarkable stability toward moisture,a llowing for benchtop transformations without the need to pretreat solvents.

The use of a bis(diphenyl)phosphine functionalized β‐diketiminato ligand, [HC{(CH 3 )C} 2 {( ortho ‐[P(C 6 H 5 ) 2 ] 2 C 6 H 4 )N} 2 ] − (PNac), as a support for germanium(II) and tin(II) chloride and phosphaketene compounds, is described. The conformational flexibility and hemilability of this unique ligand provide a versatile coordination environment that can accommodate the electronic needs of the ligated elements. For example, chloride abstraction from [(PNac)ECl] (E=Ge, Sn) affords the cationic germyliumylidene and stannyliumylidene species [(PNac)E] + in which the pendant phosphine arms associate more strongly with the Lewis acidic main group element centers, providing further electronic stabilization. In a similar fashion, chemical decarbonylation of the germanium phosphaketene [(PNac)Ge(PCO)] with tris(pentafluorophenyl)borane affords a “push–pull” stabilized phosphinidene in which one of the phosphine groups of the ligand backbone associates with the low valent phosphinidene center.