Isolation of a Phosphenium Ion with a P-C .sigma. Bond

Abstract

The first example of an X-ray crystallographically characterized two-coordinate phosphorus cation with a P-C single o bond is described. [P(mesityl)(N-i-Pr2>][AlClJ was prepared by treatment ofPCl(mesityl)(N-i-Pr2) with AhCle in dichloromethane. The phosphenium ion character of the cation is reflected in the large downfield 31P chemical shift (500 ppm) and can be compared to 313 ppm in the corresponding bis-(dialkylamido) cation [P(N-i-Pr2)zI+.

A Crystalline Phosphenium Salt Featuring the Electron-Withdrawing 2,6-Bis(trifluoromethyl)phenyl Group

“…[12] Because of their inherent electrophilicity, most of the known phosphenium salts (R 2 P ϩ ) feature two π-donor substituents such as amino groups. [13] Notable exceptions are the (amino)(mesityl)- [14] and (phosphanyl)(supermesityl)-phosphenium [15] salts, which both feature an electron-rich [ aryl substituent. Given the potential uses of phosphenium salts as strong π-acceptor ligands, [16] it was of interest to investigate the possibility of preparing a phosphenium salt featuring an electron-withdrawing group.…”

Unusual Metal-Coordinated Zwitterionic P−C−N−C−N−C Phosphido Adducts

“…Phosphenium ions have been widely studied and stabilized by various donor substituents e.g. aryl/alkylamino 3 , hydrocarbon 4 and N,C-bonded β-diketiminato groups. 5 Burford and co-workers 6 have elegantly shown phosphenium cations can be isolated upon coordination to tertiary phosphine ligands.…”

Kationische Carben‐Analoga: Donorfreie Phosphenium‐ und Arsenium‐Ionen

“…Der signifikant größere C‐P‐C Winkel von 6 , im Vergleich zu 8 , resultiert wahrscheinlich aus dem größeren sterischen Druck, der von der Mesitylgruppe ausgeht. Die C−P Bindungslängen, die in den Phosphenium‐Ionen 6 (1.772(2) Å, 1.828(1) Å) und 8 [1.781(2) Å, 1.827(2) Å] gefunden werden, sind etwas kürzer als in 2 (1.864(2) Å) oder den durchschnittlichen P−C Einfachbindungslängen in Ph 3 P (1.830(2) Å), [20] aber im Einklang mit kurzen Einfachbindungen und Werten die für [MesP(N( i ‐Pr) 2 ] + (1.787(6) Å) [21] oder [Fc 2 P] + (durchschnittlich 1.758(6) Å) [6] gefunden werden. Zum Vergleich sind die C=P Doppelbindungslängen im p‐Phosphaquinon von Yoshifuji et al.…”