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The Formation of Imidazolium Salt Intimate (Contact) Ion Pairs in Solution
Author(s) -
Zanatta Marcileia,
Girard AnneLise,
Simon Nathalia M.,
Ebeling Gunter,
Stassen Hubert K.,
Livotto Paolo R.,
dos Santos Francisco P.,
Dupont Jairton
Publication year - 2014
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201408151
Subject(s) - chemistry , ion , ionic liquid , salt (chemistry) , ion exchange , ionic bonding , hydrogen bond , catalysis , inorganic chemistry , molecular dynamics , deuterium , crystallography , computational chemistry , molecule , organic chemistry , physics , quantum mechanics
1‐ n ‐Butyl‐2,3‐dimethylimidazolium (BMMI) ionic liquids (ILs) associated with different anions undergo H/D exchange preferentially at 2‐Me group of the imidazolium in deuterated solvents. This process is mainly related to the existence of ion pairs rather than the anion basicity. The H/D exchange occurs in solvents (CDCl 3 and MeCN for instance) in which intimate contact ion pairs are present and the anion possesses a labile H in its structure, such as hydrogen carbonate and prolinate. In D 2 O, separated ion pairs are formed and the H/D exchange does not occur. A plausible catalytic cycle is that the IL behaves as a neutral base in the course of all H/D exchange processes. NMR experiments, density functional calculations, and molecular dynamics simulations corroborate these hypotheses.