Structural studies of the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate in dichloromethane using a combined DFT-NMR spectroscopic approach.
DFT methods in combination with NMR spectroscopy are used to investigate possible variants of the molecular structure of the ion pairs of the ionic liquid (IL) 1-ethyl-3-methylimidazolium tetrafluoroborate, [EMIM][BF(4)], in dichloromethane. According to the computations of the chemical shifts, experimental NMR spectra can be rationalized by an equilibrium between ca. 70-80% of structures with the anion positioned near to the C2 atom of the imidazolium ring and ca. 20-30% of structures with the anion close to the C5 and/or C4 atoms. The content of the latter structures, according to the computed Gibbs free energies, does not exceed 10%. Both the computations and the experimental NMR data suggest that the ratio of the two above-mentioned types of structures of the imidazolium-based ILs is influenced by the concentration/polarity of their dichloromethane solutions.
Katsyuba
Sergey A
SA
A.E.Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Centre of the Russian Academy of Sciences, Arbuzov Str. 8, 420088 Kazan, Russia. skatsyuba@yahoo.com
Griaznova
Tatiana P
TP
Vidis
Ana
A
Dyson
Paul J
PJ
D003198:Computer Simulation; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008752:Methylene Chloride / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D011789:Quantum Theory
C499119:1-ethyl-3-methylimidazolium tetrafluoroborate; D007093:Imidazoles; D052578:Ionic Liquids; D008752:Methylene Chloride