Functionalized Fluorophosphonium Ions

Abstract

Efforts to preparea ne lusive donor-free phosphenium ion, [R 2 P] + ,l ed us to synthesize functionalized fluorophosphonium cations of the type [R 2 P(F)X] + (X = SiEt 3 ,H ,F ), which were obtained from the relatedn eutral fluorophosphines R 2 PF and R 2 PF 3 upon protonation and reaction with solvated [Et 3 Si] + ions (R = 2,6-Mes 2 C 6 H 3 ). The hypothetical reductivee limination of [R 2 P(F)SiEt 3 ] + and [R 2 P(F)H] + affording [R 2 P] + ,E t 3 SiF and HF,r espectively, was calculated to be endothermic by 40.1 and 190.6 kJ mol À1

Intramolecular Reaction of Transient Phosphenium and Arsenium Ions Giving Rise to Isolable 9‐Phospha‐ and 9‐Arsena‐Fluorenium Ions

“…Starting from 2,6-(Me 5 C 6 ) 2 C 6 H 3 Li [12] and ECl 3 (E = P, As), we have now prepared the bis(m-terphenyl)fluoropnictogens (2,6-{Me 5 C 6 } 2 C 6 H 3 ) 2 EF (1 a, E = P; 1 b, E = As). The synthesis, solution NMR, and solid-state structural features of 1 a and 1 b resemble those of (2,6-Mes 2 C 6 H 3 ) 2 EF (E = P, [13] As [11] ) reported previously. In solution, 1 a and 1 b are characterized by 19 ] + confirmed that phosphorus was in a very similar coordination environment for both isomers.…”

Transient Phosphenium and Arsenium Ions versus Stable Stibenium and Bismuthenium Ions

“…In this work we describe the fluoride abstraction from (2,6‐Mes 2 C 6 H 3 ) 2 PF and (2,6‐Mes 2 C 6 H 3 ) 2 AsF that proceeded most likely with the formation of the transient phosphenium ion [(2,6‐Mes 2 C 6 H 3 ) 2 P] + [ 1 a ] + and the arsenium ion [(2,6‐Mes 2 C 6 H 3 ) 2 As] + [ 1 b ] + , whereby two bulky m ‐terphenyl substituents prevent the formation of dinuclear donor–acceptor complexes. Using a similar strategy, we have been recently able to isolate the heavier stibenium ion [(2,6‐Mes 2 C 6 H 3 ) 2 Sb] + [ 1 c ] + and the bismuthenium ion [(2,6‐Mes 2 C 6 H 3 ) 2 Bi] + [ 1 d ] + (Scheme ) …”

“…The fluoride abstraction from (2,6‐Mes 2 C 6 H 3 ) 2 PF with [Et 3 Si] + was impaired by the exothermic formation (Δ E =−241.0 kJ mol −1 ) of the stable donor–acceptor complex [(2,6‐Mes 2 C 6 H 3 ) 2 (F)PSiEt 3 ] + . The hypothetical elimination of Et 3 SiF and formation of [(2,6‐Mes 2 C 6 H 3 ) 2 P] + [ 1 a ] + was found to be endothermic (Δ E =+40.1 kJ mol −1 ) .…”

“…The fluoride abstraction from (2,6‐Mes 2 C 6 H 3 ) 2 PF with [Et 3 Si] + was impaired by the exothermic formation (Δ E =−241.0 kJ mol −1 ) of the stable donor–acceptor complex [(2,6‐Mes 2 C 6 H 3 ) 2 (F)PSiEt 3 ] + . The hypothetical elimination of Et 3 SiF and formation of [(2,6‐Mes 2 C 6 H 3 ) 2 P] + [ 1 a ] + was found to be endothermic (Δ E =+40.1 kJ mol −1 ) . In comparison, the fluoride abstraction from (2,6‐Mes 2 C 6 H 3 ) 2 AsF with [Et 3 Si] + might also form a thermodynamically donor–acceptor complex [(2,6‐Mes 2 C 6 H 3 ) 2 (F)AsSiEt 3 ] + (Δ E =−128.3 kJ mol −1 ); however, the competing elimination into Et 3 SiF and formation of [(2,6‐Mes 2 C 6 H 3 ) 2 As] + [ 1 b ] + was calculated to be thermodynamically more feasible (Δ E =−133.0 kJ mol −1 ), which is fully consistent with the experimental observations .…”

Intramolekulare Reaktionen transienter Phosphenium‐ und Arsenium‐Ionen führen zur Bildung isolierbarer 9‐Phospha‐ und 9‐Arsena‐Fluorenium‐Ionen

“…Ausgehend von 2,6‐(Me 5 C 6 ) 2 C 6 H 3 Li und ECl 3 (E=P, As) haben wir nun die Bis‐ m ‐terphenylpniktogenfluoride (2,6‐{Me 5 C 6 } 2 C 6 H 3 ) 2 EF ( 1 a , E=P; 1 b , E=As) hergestellt. Die Synthese, Lösungs‐NMR‐ und Festkörperstruktur‐Merkmale von 1 a und 1 b ähneln denen der zuvor beschriebenen Verbindungen (2,6‐Mes 2 C 6 H 3 ) 2 EF (E=P, As). In Lösung sind 1 a und 1 b durch chemische Verschiebungen im 19 F‐NMR‐Spektrum (in CD 2 Cl 2 ) bei δ=−200.3 (E=P) und −216.0 ppm (E=As) charakterisiert, während 1 a ein 31 P‐NMR‐Signal bei δ=193.8 ppm zeigt.…”