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Ion‐Pair Formation in the Ionic Liquid 1‐Ethyl‐3‐methylimidazolium Bis(triflyl)imide as a Function of Temperature and Concentration
Author(s) -
Köddermann Thorsten,
Wertz Christiane,
Heintz Andreas,
Ludwig Ralf
Publication year - 2006
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200600034
Subject(s) - ionic liquid , imide , chemistry , ion , chloroform , ionic bonding , fourier transform infrared spectroscopy , hydrogen bond , inorganic chemistry , dilution , crystallography , analytical chemistry (journal) , molecule , polymer chemistry , organic chemistry , catalysis , thermodynamics , physics , quantum mechanics
The structures and ion‐pair formation in the ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide are studied by a combination of FTIR measurements and DFT calculations. We could clearly distinguish imidazolium cations that are completely H‐bonded to anions from those that are single H‐bonded in ion pairs. Ion‐pair formation already occurs in the neat IL and rises with temperature. Ion‐pair formation is strongly promoted by dilution of the IL in chloroform. In these weakly polar environments ion pairs H‐bonded via C(2)H are strongly favored over those H‐bonded via C(4,5)H. This finding is in agreement with DFT (gas phase) calculations, which show a preference for ion pairs H‐bonded via C(2)H as a result of the acidic C(2)H bond.