An Acyclic Arsenium Cation Stabilised by a Single P–As π‐Interaction and a Cyclic Diphosphinophosphonium Salt

Abstract

Stable acyclic arsenium cations R2As+, isoelectronic analogues of germylenes, are rare in comparison to the corresponding phosphenium cations. The first example of a diphosphaarsenium salt, [{(Dipp)2P}2As][Al{OC(CF3)3}4]⋅11/2 PhMe, is described. This salt exhibits remarkable stability due to the delocalisation of a lone pair from a planar phosphorus centre into the vacant p‐orbital at arsenic; the bonding in 2 has been probed by DFT calculations. An attempt to synthesise an analogous diphosphaphosphenium salt unexpectedly generated the cyclic phosphonium salt [cyclo‐{(Mes)P}2P(Mes)2][BArF4]⋅CyMe through the cyclisation of a putative phosphine‐substituted diphosphene cation intermediate.

Donor-Stabilized Antimony(I) and Bismuth(I) Ions: Heavier Valence Isoelectronic Analogues of Carbones

“…Schulz et al reported on the synthesis of a 3-bisma-2-pentazenium cation [R 2 N-N­(R)-BiN­(R)-NR 2 ] + (R = (CH 3 ) 3 Si) . Izod et al isolated a phosphine-stabilized acyclic arsenium cation [{(Dipp) 2 P} 2 As]­[Al­{OC­(CF 3 ) 3 } 4 ] . In 2018, Beckmann et al reported two-coordinated stibenium and bismuthenium ions, [(2,6-Mes 2 C 6 H 3 ) 2 E]­[BArF 4 ] (E = Sb, Bi), obtained by using bulky meta -terphenyl substituents, which were heavier isoelectronic analogues of carbenes .…”

Gradual Donor Stabilization of a Transient Ferrocene Bridged Bisphosphanyl Phosphenium Cation

“…A closely related bisphosphanylarsenium ion has been reported few years ago, whereas the corresponding phosphenium ion underwent rearrangement and could not be detected. 15 We have chosen the triphospha [3]ferrocenophane scaffold for our investigation which has been demonstrated to limit the number of isomers emerging from the stereogenic nature of the flanking phosphanyl units. 16 The analogous 1,3,2-diazaphospha- [3]ferrocenophane scaffold has already been successfully employed for isolation of a phosphenium ion I (Figure 1).…”

Diazaphospholene and Diazaarsolene Derived Homogeneous Catalysis

“…The first isolated and structurally characterized arsenium cations were reported by Burford in 1992, and although much rarer than phospheniums, a number of examples do exist . Although a lone pair and a vacant p ‐orbital are still present, their bonding to transition metals is typically confined to Lewis acid chemistry, where there is little to no σ‐donation from the lone pair .…”