Ion-pair dissociation equilibria for hexachloroantimonate salts of stable organic cations in dichloromethane

Abstract

Ion-pair dissociation constants have been measured for hexachloroantimonate salts of tropylium, trityl, xanthylium, 2,4,6-trimethylpyrylium, benzyldimethylphenylammonium, tetraethylammonium, and tri-isopentyl-n-butylammonium cations in dichloromethane solvent at two temperatures. Heat and entropy terms for the dissociation equilibria indicate only slight increases in solvation on dissociation. Values of equivalent conductance at infinite dilution for SbCl₆^– and for the individual organic cations have been determined and there is good agreement between calculated values of effective interionic distance (a) and corresponding sums of Stokes radii (λ₀⁺+λ₀^–).