Highly conducting ionic liquids based on 1-ethyl-3-methylimidazolium cation

Highly conducting EMI-based room-temperature (RT) ionic liquids containing transition metals [EMI][M(III)Cl-4] (M = Fe, Fe-0.5 Ga-0.5 and Ga) were prepared, and their thermal and physical properties were well investigated, where EMI is 1-ethyl-3-methylimidazolium. All the salts are liquid at RT and show a wide liquid range. High ionic conductivities (1.8-2.0 x 10(-2) S cm(-1) at 20 degrees C) and low viscosities (12-14 cP at 30 degrees C) are comparable to those of N(CN)(2) and C(CN)(3) salts. The FeCl4 and Fe0.5Ga0.5Cl4 melts exhibit a Curie-like behavior arising from the S = 5/2 spins on iron(III) ions, indicating the first conductive-paramagnetic bifunctional RT ionic liquids. On cooling, the solidified FeCl4 salt passes through an anti ferromagnetic transition at 4.2 K. On the basis of sixteen EMI-based RT ionic liquids including the present salts, it has become apparent that the conductivity is proportional to the reciprocal of the product of the anion weight and the viscosity.