Thermally stable bis(trifluoromethylsulfonyl)imide salts and their mixtures
We show that both tetraphenylphosphonium bis(trifluoromethylsulfonyl)imide ([PPh4][NTf2]) and Cs[NTf2] are low melting salts of exceptionally high and also very similar thermal stability. This similarity indicates that the thermal stability is dominated by the anion. Moreover, eutectic mixtures of [PPh4][NTf2] and Cs[NTf2] with melting points below 100 °C are presented. Surface analysis of the latter in the liquid state reveals a surprising depletion of [PPh4]+ ions from the surface.