An Aliphatic Solvent-Soluble Lithium Salt of the Perhalogenated Weakly Coordinating Anion [Al(OC(CCl3)(CF3)2)4]-

The facile synthesis of a new highly aliphatic solvent-soluble Li+ salt of the perhalogenated weakly coordinating anion [Al(OC(CCl3)(CF3)(2))(4)](-) and its application in stabilizing the Ph3C+ cation were investigated. The lithium salt Li[Al(OC(CCl3)(CF3)(2))(4)](-) (4) was prepared by the treatment of 4 mol equiv of HOC(CCl3)(CF3)(2) with purified LiAlH4 in n-hexane from -20 degrees C to room temperature. Compound 4 is highly soluble in both polar and nonpolar solvents, and it bears both CCl3 and CF3 groups, resulting in a lower symmetry around the Al center compared to that of Li[Al(OC(CF3)(3))(4)] (1). Treatment of 4 with Ph3CCl afforded the ionic compound [Ph3C][Al(OC(CCl3)(CF3)(2))(4)] (5) bearing the Ph3C+ cation with concomitant elimination of LiCl, suggesting the potential application of [Al(OC(CCl3)(CF3)(2))(4)](-) in stabilizing reactive cationic species. Compounds 4 and 5 were fully characterized by spectroscopic and structural methods.