Ion-Pair and Triple-Ion Formation by Some Tetraalkylammonium Iodides in Binary Mixtures of 1,4-Dioxane + Tetrahydrofuran

Electrical conductances of tetraalkylammonium iodides, R 4 NI (R = pentyl to heptyl) have been measured at 298.15 K in low-permittivity mixtures of 1,4-dioxane (ε = 2.21) and tetrahydrofuran (ε = 7.58). Minima in the conductometric curves (Λ versus √ c ) were observed for electrolyte concentrations dependent upon both the electrolyte and the binary solvent mixture. The conductance data have been analyzed by the Fuoss−Kraus theory of triple ions. A numerical evaluation of ion-pair and triple-ion formation constants ( K P and K T ) was made, and the results have been discussed in terms of a molecular scale model.