Relative molar Gibbs energies of cation transfer from a molecular liquid to ionic liquids at 298.15 K

Abstract

Molar Gibbs energies of Ag⁺, Cu²⁺, Zn²⁺ and Cd²⁺ transfer from dimethylsulfoxide (DMSO), a reference molecular liquid, to a number of ionic liquids (IL), Δ_tG(DMSO → IL), were obtained from M|Mⁿ⁺ electrode potentials at 298.15 K. The ionic liquids consisted of various tetraalkylammonium cations and Cl⁻, Br⁻, BF₄⁻, PF₆⁻ or N(CF₃SO₂)₂⁻ anions. The measured M|Mⁿ⁺ (0.01 M, IL) potentials depend both on the tetraalkylammonium cation as well as on the anion. The transfer of cations from DMSO to ionic liquids brings about positive or negative changes of the molar Gibbs energy. The most important factor influencing the transfer molar Gibbs energy is the anionic component of the ionic liquid, which solvates the cation. In general, the molar Gibbs energy of cations in ionic liquids having N(CF₃SO₂)₂⁻ anion is lower than in those having halide or tetrafluoroborate anions.