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 °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.