Synthesis of Selected Cationic Pnictanes [L_nPnX_3–n]ⁿ⁺ (L = Imidazolium-2-yl; Pn = P, As; n = 1–3) and Replacement Reactions with Pseudohalogens

Abstract

Herein we report on reactions of "imidazoliumyl-transfer" reagents [L((R/R'))SiMe3][OTf] (4((R/R'))[OTf]); L = imidazolium-2-yl, R/R': Me/Me, (i)Pr/Me, Dipp/H, Dipp/Cl) with pnictogen trichlorides PnCl3 (Pn = P, As, Sb) in various stoichiometries. In the case of the 1:1 reaction of [L((R/R'))SiMe3][OTf] with PCl3 the corresponding cationic imidazoliumyl-substituted dichlorophosphanes [L((R/R'))PCl2](+) (1P((R/R')))(+) are obtained as triflate salts on a multigram scale. We found that the reactions using various stoichiometries of [L((R/R'))SiMe3][OTf] and PnCl3 are less selective in the case of the heavier congeners or by decreasing steric demand of the R-group attached to the N atoms of the heterocycle. An equilibrium between the monocation [L((Me/Me))PCl2](+) (1P((Me/Me)+)), the dication [L((Me/Me))2PCl](2+) (2P((Me/Me)2+)), and the trication [L((Me/Me))3P](3+) (5P((Me/Me)3+)) is observed in solution. Reactions of the monocationic derivatives [L((R/R'))PnCl2][OTf] (Pn = P, As) with Me3SiX (X = CN, N3) resulted in the exchange of the chloro groups for the respective pseudohalogen and yielded the dicyano [L((R/R'))Pn(CN)2][OTf] (6Pn((R/R'))[OTf]) and diazido-substituted pnictanes [L((R/R'))Pn(N3)2][OTf] (7Pn((R/R'))[OTf]), respectively. All new compounds are thoroughly characterized by multinuclear NMR, IR, and Raman spectroscopy. For most cases the molecular structure was confirmed by X-ray crystal structure analysis.

Selective and Reversible Fluoride Complexation from Water by a Cyclic Tri(phosphonio)methanide Dication

“…[7][8][9] Certain phosphonium cations also possess ahigh F À affinity, [10,11] when hypercoordination is possible. Thei mplementation of electron withdrawing substituents (I) [14,15] and/or the increase of the overall charge of the cations by the introduction of onio-substituents (II) [16] are suitable concepts to achieve this goal (Scheme 1, left). Thei mplementation of electron withdrawing substituents (I) [14,15] and/or the increase of the overall charge of the cations by the introduction of onio-substituents (II) [16] are suitable concepts to achieve this goal (Scheme 1, left).…”

Tris(1‐methyl‐imidazol‐2‐yl)phosphane Complexes of Pnictogen, Tetrel, and Triel Cations

“…Both compounds have short M−N distances [As−N 1.931(2)–1.937(2), Sb−N 2.151(2)–2.159(2) Å]. The P−C bond lengths are only slightly longer in [P(Im) 3 As] 3+ (1.829(2)–1.836(2) Å) and [P(Im) 3 Sb] 3+ (1.830(3)–1.835(3) Å) than in P(Im) 3 (1.817–1.829 Å) or in the trimethylated ligand, [P(ImMe) 3 ] 3+ (1.813–1.825 Å) . The sum of angles around phosphorus follow the trend, °Σ P(Im) 279.20 [P(Im) 3 As] 3+ <285.09° [P(Im) 3 Sb] 3+ <302.95° P(Im) 3 <312.20° [P(ImMe) 3 ] 3+ .…”

Recent Advances in Imidazoliumyl‐Substituted Phosphorus Compounds

“…A clean formation of the diimidazoliumyl‐substituted derivative 97 b [OTf] 2 is observed for the reaction of two equivalents of 95 b [OTf] with PCl 3 (Scheme ) . For the reaction of two equivalents of 95 a [OTf] with PCl 3 , a mixture of the mono‐, di‐, and tricationic derivatives is observed in solution . For derivatives 95 c [OTf] and 95 d [OTf], the reaction to the respective dications is hampered owing to steric hindrance …”

“…For the reaction of two equivalents of 95 a [OTf] with PCl 3 , a mixture of the mono‐, di‐, and tricationic derivatives is observed in solution . For derivatives 95 c [OTf] and 95 d [OTf], the reaction to the respective dications is hampered owing to steric hindrance …”

“…The neat reaction of three equivalents of 95 a [OTf] with PCl 3 at 140 °C gives the triflate salt of triimidazoliumyl‐substituted trication 98 3+ (Scheme ) . A comparison of the 31 P NMR chemical shifts of monocations 96 a + ( δ (P)=107.2 ppm), 96 b + ( δ (P)=109.1 ppm), 96 c + ( δ (P)=113.5 ppm), 96 d + ( δ (P)=114.9 ppm), dications 97 a 2+ ( δ (P)=6.9 ppm), 97 b 2+ ( δ (P)=19.9 ppm), and trication 98 3+ ( δ (P)=−82.9 ppm) reveals a trend to higher field with an increased number of imidazoliumyl‐substituents and an increased overall charge of the respective compounds.…”