Synthesis and Characterization of the Tetrakis(pentafluoroethyl)aluminate.

While perfluorinated aryl, aryloxy and alkoxy aluminum species are well-established as weakly coordinating anions (WCAs), corresponding perfluoroalkyl aluminum derivatives are virtually unknown.  Reaction of Si(C 2 F 5 ) 3 CH 3  with Li[AlH 4 ] afforded the tetrakis(pentafluoroethyl)aluminate, [ Al(C 2 F 5 ) 4 ] - . Several salts of the  [ Al(C 2 F 5 ) 4 ] -  ion were synthesized and characterized by NMR spectroscopic methods, mass spectrometry, X-ray diffraction studies and elemental analysis.