Syntheses, structures and properties of 1-ethyl-3-methylimidazolium salts of fluorocomplex anions

Abstract

Fluoroacid-base reactions of a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium fluorohydrogenate (EMIm(HF)2.3F, EMIm = 1-ethyl-3-methylimidazolium cation), and Lewis fluoroacids (BF3, PF5, AsF5, NbF5, TaF5 and WF6) give EMIm salts of the corresponding fluorocomplex anions, EMImBF4, EMImPF6, EMImAsF6, EMImNbF6, EMImTaF6 and EMImWF7, respectively. Attempts to prepare EMImVF6 by both the acid-base reaction of EMIm(HF)2.3F with VF5 and the metathesis of EMImCl with KVF6 failed due to the strong oxidizing power of the pentavalent vanadium, whereas EMImSbF6 was successfully prepared only by the metathesis of EMImCl and KSbF6. EMImBF4, EMImSbF6, EMImNbF6, EMImTaF6 and EMImWF7 are liquids at room temperature whereas EMImPF6 and EMImAsF6 melts at around 330 K. Raman spectra of the obtained salts showed the existence of the EMIm cation and corresponding fluorocomplex anions. IR spectroscopy revealed that strong hydrogen bonds are not observed in these salts. EMImAsF6(mp 326 K) and EMImSbF6(mp 283 K) are isostructural with the previously reported EMImPF6. The melting point of the hexafluorocomplex EMIm salt decreases with the increase of the size of the anion (PF6- < AsF6- < SbF6- <NbF6- approximately TaF6-).

Raman Spectroscopy and Ab-Initio Model Calculations on Ionic Liquids

“…As expected, in many papers only the anions are varied and the cation is kept or vice versa. Matsumoto et al e.g., studied syntheses, structures, and properties (e.g., Raman spectra) of 1-ethyl-3-methylimidazolium salts of a series of fluorocomplex anions [72,73].…”

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

“…126 due to no density data), which shows a low conductivity of 2:8 Â 10 À3 S cm À1 and high viscosity of 162 cP. 845,864 The long alkyl chain and hard basicity of C 3 F 7 CO 2 in salt 19 and large molecular weight and low symmetry of WF 7 (C 3v symmetry 867 ) in salt 16 might cause their high viscosity and low conductivity. The poor conductivity (ca.…”

“…73, they can be classified into three categories (groups a-c) based on a parameter d=, which roughly corresponds to a slope of the ' vs M a À1 plot. a) d= < 0:02: X = WF 7 (16), 867 854,855 FeCl 4 (4), 854,855 and AlCl 4 (6). 853 The highly viscous salts in group a show low ionic conductivity, which is insensitive to M a , presumably indicating that the individual molecules are largely retarded by strong and specific intermolecular interactions to have a poor self-diffusivity.…”

Influence of Dopant Type and Orientation of Silicon Anodes on Performance, Efficiency and Corrosion of Silicon–Air Cells with EMIm(HF)2.3F Electrolyte

“…One of the possible approaches is the usage of EMIm(HF) 2.3 F electrolyte which possesses high conductivity, low viscosity and chemical stability in air. [7][8][9][10] The proof of concept, that substantial discharge was possible when using EMIm(HF) 2.3 F electrolyte, was proposed in 2010 according to the following reactions: 11 Anode: Si + 12(HF) 2 Additionally, a screening of several anode materials -As-, Sband B-doped Si wafers -was performed, in which the cell potential at intermediate current densities as determined from potentiodynamic polarization measurements, was set as major criterion. The corrosion current densities as obtained by the Tafel fits from the polarization experiments for the different wafer types were also considered for the material selection.…”