Thermally stable bis(trifluoromethylsulfonyl)imide salts and their mixtures

Abstract

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.