A new room temperature ionic liquid of oxyfluorometallate anion: 1-Ethyl-3-methylimidazolium oxypentafluorotungstate (EMImWOF5)

The first room temperature ionic liquid (room temperature molten salt) containing oxyfluorometallate anion, 1-ethyl-3-methylimidazolium oxypentafluorotungstate (EMImWOF5), has been synthesized and characterized compared to other known EMIm fluorocomplex salts. EMImWOF5 is synthesized by two routes: one is the hydrolysis of EMImWF7 and the other is the fluoroacid–base reaction of EMIm(HF)2.3F and WOF4. EMImWOF5 is a hydrophilic room temperature ionic liquid but is stable in aqueous solution. From the result of DSC analysis, EMImWOF5 exhibits a glass transition at 182 K and melts at 253 K. The density, conductivity and viscosity at 298 K are 2.25 g cm−3, 3.0 mS cm−1 and 105.1 cP, respectively.