A magnetic ionic liquid has been identified by Hayashi and Hamaguchi in 2004 as an ionic liquid based on the imidazole 1-butyl-3-methylimidazolium chloride and ferric chloride. Due to the presence of high spin FeCl₄⁻ the liquid is paramagnetic and a magnetic susceptibility of 40.6 × 10−6 emu g^-1 is reported. A simple magnet suffices to attract the liquid in a test tube.

references

Discovery of a Magnetic Ionic Liquid [bmim]FeCl4, Satoshi Hayashi, Hiro-o Hamaguchi Chemistry Letters, Vol. 33 (2004) 1590-1591