Premium
In Search of Ionic Liquids Incorporating Azolate Anions
Author(s) -
Katritzky Alan R.,
Singh Shailendra,
Kirichenko Kostyantyn,
Smiglak Marcin,
Holbrey John D.,
Reichert W. Matthew,
Spear Scott K.,
Rogers Robin D.
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500840
Subject(s) - ionic liquid , thermogravimetric analysis , differential scanning calorimetry , salt (chemistry) , chemistry , ion , ionic bonding , trigonal crystal system , inorganic chemistry , crystal structure , glass transition , crystallography , organic chemistry , polymer , catalysis , physics , thermodynamics
Twenty‐eight novel salts with tetramethyl‐, tetraethyl‐, and tetrabutylammonium and 1‐butyl‐3‐methylimidazolium cations paired with 3,5‐dinitro‐1,2,4‐triazolate, 4‐nitro‐1,2,3‐triazolate, 2,4‐dinitroimidazolate, 4,5‐dinitroimidazolate, 4,5‐dicyanoimidazolate, 4‐nitroimidazolate, and tetrazolate anions have been prepared and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and single‐crystal X‐ray crystallography. The effects of cation and anion type and structure on the physicochemical properties of the resulting salts, including several ionic liquids, have been examined and discussed. Ionic liquids (defined as having m.p.<100 °C) were obtained with all combinations of the 1‐butyl‐3‐methylimidazolium cation ([C 4 mim] + ) and the heterocyclic azolate anions studied, and with several combinations of tetraethyl or tetrabutylammonium cations and the azolate anions. The [C 4 mim] + azolates were liquid at room temperature exhibiting large liquid ranges and forming glasses on cooling with glass‐transition temperatures in the range of −53 to −82 °C (except for the 3,5‐dinitro‐1,2,4‐triazolate salt with m.p. 33 °C). Six crystal structures of the corresponding tetraalkylammonium salts were determined and the effects of changes to the cations and anions on the packing of the structure have been investigated.