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.

A series of electrophilic bis-fluorophosphonium dications dervied from diphosphines with naphthalene- and (oligo)methylene-linkers is presented. The resulting Lewis acidity is demonstrated to depend on the spatial proximity between the P moieties as evidenced in several Lewis acid catalyzed transformations.

Many transition-metal complexes containing a broad variety of degraded or aggregated P n units, resulting from P 4 activation, have been discovered and described. [1][2][3] In comparison, the functionalization of P 4 with main-group fragments represents a new and rapidly developing field. Recently, Bertrand and co-workers have found that carbenes react with white phosphorus, with or without inducing its fragmentation or aggregation [4] . Similarly, heavier carbenelike main-group-element derivatives containing Al, [5] Ga, [6] Tl, [7] and Si, [8] insert into the PÀP bonds of the P 4 tetrahedron. [9] Krossing and co-workers have reported the insertion of in situ-prepared, highly electrophilic, carbene-analogous [PX 2 ] + cations (X = Br, I) into one of the P À P bonds of P 4 , yielding phosphorus-rich binary cage cations [P 5 X 2 ] + (1, see below). Although highly reactive, these cations could be successfully isolated using non-oxidizing, weakly coordinating counteranions of type [Al(OR) 4 ] À (OR = polyfluorinated aliphatic alkoxide). [10] In contrast to the well-developed chemistry of oligophosphorus anions, [11] 1 represents the only structurally characterized cationic homoatomic phosphorus cluster reported.www.angewandte.de acid/chloropnictogen systems with P 4 and the behavior of the reaction products in organic solvents.

The cage compound [DippP5 Cl][GaCl4 ] (Dipp=2,6-diisopropylphenyl) reacts with an NHC (N-heterocyclic carbene) by an unprecedented [3+2] fragmentation of the P5 (+) core. This yields an imidazoliumyl-substituted P3 species featuring a triphosphaallyl anion motif and a neutral P2 compound. The mechanism of the fragmentation reaction was elucidated by means of experimental and quantum chemical methods.