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.

A cationic phosphoranide featuring a normal and an abnormal imidazoliumyl substituent was prepared through the reaction of a P‐centered cation with an N‐heterocyclic carbene (NHC). The remarkable reactivity of this compound allows the formation of two‐ or three‐coordinate P‐centered cations, illustrating the ability of imidazoliumyl substituents to stabilize high‐ and low‐coordinated P atoms.

A highly Lewis acidic diphosphonium dication [(C10H6)(Ph2P)2](2+) (1), in combination with a Lewis basic phosphine, acts as a purely phosphorus-based frustrated Lewis pair (FLP) and abstracts hydride from [HB(C6F5)3](-) and Et3SiH demonstrating the remarkable hydridophilicity of 1. The P-based FLP is also shown to activate H2 and C-H bonds.

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.

Fluorobenzene solutions of RPCl2 and a Lewis acid such as ECl3 (E = Al, Ga) in a 1:1 ratio are used as reactive sources of chlorophosphenium cations [RPCl]+, which insert into P–P bonds of dissolved P4. This general protocol represents a powerful strategy for the synthesis of new cationic chloro-substituted organophosphorus [RP5Cl]+-cages as illustrated by the isolation of several monocations (21a-g +) in good to excellent yields. For singular reaction two possible reaction mechanisms are proposed on the basis of quantum chemical calculations. The intriguing NMR spectra and structures of the obtained cationic [RP5Cl]+-cages are discussed. Furthermore, the reactions of dichlorophosphanes and the Lewis acid GaCl3 in various stoichiometries are investigated to obtain a deeper understanding of the species involved in these reactions. The formation of intermediates such as RPCl2·GaCl3 (14) adducts, dichlorophosphanylchlorophosphonium cations [RPCl2–RPCl]+ (16 +) and [RPCl2–RPCl–GaCl3]+ (17 +) in reaction mixtures of RPCl2 and GaCl3 in fluorobenzene strongly depends on the basicity of the dichlorophosphane RPCl2 (R = tBu, Cy, iPr, Et, Me, Ph, C6F5) and the reaction stoichiometry.