Safe preparation and purification of sodium tetrakis[(3,5-trifluoromethyl)phenyllborate (NaBArF24):: Reliable and sensitive analysis of water in solutions of fluorinated tetraarylborates

A safe, convenient preparation of the reagent sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate (NaBArF24) has been devised by utilizing a magnesium-bromine exchange reaction in the absence of metallic magnesium. Purified material was then rigorously dried over P2O5 (NaBArF24 with < 500 ppm H2O by mass) or recrystallized as a hydrate (NaBArF24 center dot(2.6 +/- 0.1)H2O). Accurate analysis of the water content of these samples by H-1 NMR was accomplished by using dimethylzirconocene (Cp2Zr(CH3)(2)).