Ionic solvation of tetrabutylammonium hexafluorophosphate in pure nitromethane, 1,3-dioxolane and nitrobenzene: A comparative physicochemical study

Electrolytic conductivities (Λ), densities (ρ), viscosities (η), refractive indices (nD) and speed of sound (u) of tetrabutylammonium hexafluorophosphate (Bu4NPF6) have been studied in nitromethane (NM), 1,3-dioxolane (DO) and nitrobenzene (NB) at 298.15 K. The limiting molar conductivities (Λo), association constants (KA), and the distance of closest approach of the ion (R) have been evaluated using the Fuoss conductance equation (1978). The Walden product is obtained and discussed. The deviation of the conductmetric curves (Λ vs √c) from linearity for the salt in 1,3-dioxolane indicates triple-ion formation, and therefore the corresponding conductance data have been analyzed by using the Fuoss–Kraus theory of triple-ions. The limiting apparent molar volumes (ϕV), experimental slopes (SV*) derived from the Masson equation, and viscosity A and B coefficients using the Jones–Dole equation have been interpreted in terms of ion–ion and ion–solvent interactions, respectively. Molar refraction (RM) have been calculated using the Lorentz–Lorenz equation. The adiabatic compressibility (βS) has been evaluated using the u   values. There after, the limiting apparent molar adiabatic compressibility (ϕKo) have been calculated and discussed.

► Physicochemical study of Bu4NPF6 in nitromethane, 1,3-dioxolane and nitrobenzene.
► Triple-ion formation in 1,3-dioxolane.
► More ion–solvent interaction in nitrobenzene.
► Less ion–ion interaction than ion–solvent interaction in all the solvents.