Lattice energies, ionic liquid structure

The term ionic liquids refers to liquids that exclusively contain ions. They are liquid salts which do not need to be dissolved in a solvent such as water. As a rule, the term ionic liquids is used when the corresponding salts are liquid at temperatures lower than 100 °C. Examples of suitable cations are alkylated imidazolium, pyridin-ium, ammonium or phosphonium ions. The size and the symmetry of the participating ions prevents the formation of a strong crystal lattice, meaning that only small amounts of thermal energy are needed to overcome the lattice energy and break up the solid crystal structure. 

Besides the prediction of structural information of various phases, calculations of thermochemical quantities such as the heat of formation in gas, liquid, and solid phases, the heat of vaporization for liquids, the heat of sublimation for ionic solids or the lattice energy for ionic solids represent important quantitative measures related to stability and phase-transformation properties of the compounds of interest. Calculations of such properties are feasible and we will describe the methods for performing them. 

An ionic liquid generally consists of a large nitrogen-containing organic cation and a smaller, inorganic anion. The asymmetry reduces the lattice energy of the crystalline structure and results... 

Interestingly, there is, currently, only one report of a crystal structure of a naked fluoride ion-containing ionic liquid, namely, [NH30HJF melting at 97-98°C (lattice potential energy, 1/ l =... 

Physical and transport properties of bis(trifl.uoromethylsulfonyl)imide-based room-temperature ionic liquids Application to the diffusion of tris(2,2 -bipyridyl)ruthenium(II). Journal of the Electrochemical Society, 158,1, (2010), F1-F9 Papoular, R. J. Allouchi, H. Chagnes, A. Dzyabchenko, A. Carre, B. Lemordant, D. V. Agafonov (2005). X-ray powder diffraction structure determination of y butyrolactone at 180 K phase-problem solution from the lattice energy minimization with two independent molecules. Acta Crystallographica, Section B. Structural Science, B61, (2005), 312-320... 

Non-aqueous Solvation.—Structural radii and electron-cloud radii, together with lattice enthalpies and enthalpies of solvation of ionic crystals, have been reviewed.84 The free energies of transfer, AGtr(K+), of potassium ions from water to 14 non-aqueous solvents have been reported, and they were derived from measurements in an electrochemical cell assumed to have a negligible liquid-junction potential. The essentially electrostatic nature of its solvation allows K+ to be used as a model for non-specific solvent-ion interactions. A... 

---