Reappraisal of the energetics of the thallium(I) halides

Abstract

The crystal energies of the thallium(I) halides, particularly TlF, have been recalculated. The results, in kcal mol^–1, are TlF: –196 (–200) TlCl: –169 (–178) TlBr: –163 (–174) TlI: –157 (–168); the values in parentheses have been derived from a Born-Haber cycle. The enthalpy of hydration of the Tl⁺ ion is –97 kcal mol^–1, and the mean molal ionic activity coefficient of TlF in saturated solution is 0.687. The interatomic bonding in the thallium(I) halides is compared with that in the silver halides.