title: Vaporization and formation enthalpies of 1-alkyl-3-methylimidazolium tricyanomethanides.
abstract: Thermochemical studies of the ionic liquids 1-ethyl-3-methylimidazolium tricyanomethanide [C(2)MIM][C(CN)(3)] and 1-butyl-3-methylimidazolium tricyanomethanide [C(4)MIM][C(CN)(3)] have been performed in this work. Vaporization enthalpies have been obtained using a recently developed quartz crystal microbalance (QCM) technique. The molar enthalpies of formation of these ionic liquids in the liquid state were measured by means of combustion calorimetry. A combination of the results obtained from QCM and combustion calorimetry lead to values of gaseous molar enthalpies of formation of [C(n)MIM][C(CN)(3)]. First-principles calculations of the enthalpies of formation in the gaseous phase for the ionic liquids [C(n)MIM][C(CN)(3)] have been performed using the CBS-QB3 and G3MP2 theory and have been compared with the experimental data. Furthermore, experimental results of enthalpies of formation of imidazolium-based ionic liquids with the cation [C(n)MIM] (where n = 2 and 4) and anions [N(CN)(2)], [NO(3)], and [C(CN)(3)] available in the literature have been collected and checked for consistency using a group additivity procedure. It has been found that the enthalpies of formation of these ionic liquids roughly obey group additivity rules.
authors: Department of Physical Chemistry,  University of Rostock , Dr-Lorenz-Weg-1, 18059 Rostock, Germany.
authors: Vladimir N
authors: VN
authors: Emel'yanenko
authors: Dzmitry H
authors: DH
authors: Zaitsau
authors: Sergey P
authors: SP
authors: Verevkin
authors: Andreas
authors: A
authors: Heintz
authors: Karsten
authors: K
authors: Voss
authors: Axel
authors: A
authors: Schulz