Activation of Acetonitrile with (C2 F5 )3 PF2 and Amines.

Acetonitrile is deprotonated by a combination of the strong Lewis acid (C2 F5 )3 PF2 and triethylamine. The resulting cyanomethyl function is bound to the phosphorus moiety, affording the highly stable salt [HNEt3 ][P(C2 F5 )3 F2 (CH2 CN)]. Salt metathesis reactions furnished the corresponding [Cu(MeCN)2 ]+ and [Ag(MeCN)]+ derivatives in which the CH2 CN substituent of the anion [P(C2 F5 )3 F2 (CH2 CN)]- coordinates to the metal. An investigation of the gas separation capability of the silver salt [Ag(MeCN)][P(C2 F5 )3 F2 (CH2 CN)] shows an uptake of 1.7 equivalents of isobutene from a propane/isobutene mixture. The reaction of (C2 F5 )3 PF2 with acetonitrile and diethylamine furnishes [P(C2 F5 )3 F2 {NHC(CH3 )NEt2 }]-a phosphate featuring an amidine ligand which formally results from hydroamination of acetonitrile by HNEt2 . Exchange of HNEt2 with the primary amines H2 NPh and H2 NBu leads to comparable amidine salts that exhibit a solvent-dependent conformational isomerism.