Functionalized Fluorophosphonium Ions.

Efforts to prepare an elusive donor-free phosphenium ion, [R2 P]+ , led us to synthesize functionalized fluorophosphonium cations of the type [R2 P(F)X]+ (X=SiEt3 , H, F), which were obtained from the related neutral fluorophosphines R2 PF and R2 PF3 upon protonation and reaction with solvated [Et3 Si]+ ions (R=2,6-Mes2 C6 H3 ). The hypothetical reductive elimination of [R2 P(F)SiEt3 ]+ and [R2 P(F)H]+ affording [R2 P]+ , Et3 SiF and HF, respectively, was calculated to be endothermic by 40.1 and 190.6 kJ mol-1 .

Al(OCArF3)3 - a thermally stable Lewis superacid.

The adduct free Lewis superacid Al(OCArF3)3 was obtained by the reaction of ArF3COH with AlEt3 and fully characterized (ArF = C6F5). It comprises a high thermal stability up to 180 °C and a distinct reactivity towards Lewis bases, as exemplified by the isolation of the neutral adducts Al(OCArF3)·D (D = MeCN, THF, Et2O, pyridine, OPEt3), the fluoride complexes [Q][FAl(OCArF)3] (Q+ = Cs+, Ag+, Tl+, [S(NMe2)3]+, [Ph3C]+, Li+, [NBu4]+, [FeCp2]+) and the chloride complex [Ph3C][ClAl(OCArF)3].