Reactivity and Thermal Stability of Hexafluorides

The review deals with the possibility of using various physicochemical characteristics of the hexafluorides of p, d, and f elements for a comparative estimation of their thermal stability and reactivity. The force constants of EF₆ molecules, the average bond energy and length, and also the thermodynamic stability constants of the octahedral EF₆ molecules have been used as characteristic properties.
It has been shown that the force constants of the E–F bond are not effective characteristics of the thermal stability and reactivity of all hexafluorides in reactions where more than one E–F bond is dissociated. Only the thermodynamic stability constants can serve as an objective criterion for the assessment when account is taken of definite dissociation mechanisms of EF₆ molecules (complete or incomplete dissociation). Within the limits of individual groups of 4d, 5d, and 5f elements and also sulphur, selenium, and tellurium, the variation of the force constants and thermodynamic stability in relation to the incomplete dissociation of the hexafluorides corresponds to the experimental sequences of their thermal stabilities.
The bibliography includes 85 references.