Physicochemical and Electrochemical Properties of Room-Temperature Ionic Liquids Based on Quaternary Phosphonium Cations and Tetracyanoborate Anion

The physicochemical and electrochemical properties of room-temperature ionic liquids based quaternary phosphonium cations together with tetracyanoborate anion are presented in this report. It was found that the tetracyanoborate anion based phosphonium ionic liquids showed relatively low viscosity, high conductivity and considerably high thermal stability when compared to those of the corresponding ammonium and the conventional phosphonium ionic liquids. The introduction of a methoxy group into the phosphonium cation tended to reduce the thermal stability and the electrochemical stability of the ionic liquids.