Thermochemistry of hexafluoro-anions of MIV(M = Si, Ti, Mn, or Re) and lattice energy calculations for their salts

Abstract

Enthalpies of solution of salts of MF₆^2–(M = Si^IV, Ti^IV, Mn^IV, or Re^IV), reactions of anions of this type for M = Os^IV, Ru^IV, and Re^IV, and enthalpies of hydrolysis of hexafluoro-manganate(IV) and -rhenate(IV) ions are reported. From these results and appropriate ancillary thermochemical data and extra-thermodynamic assumptions, we have estimated ion hydration enthalpies for a range of MF₆^2– ions, enthalpies of formation of K₂[MnF₆], Rb₂[MnF₆], K₂[ReF₆], and several MF₆^2– ions, and two-fluoride ion affinities of the tetrafluorides of silicon, titanium, and manganese. The lattice enthalpies required in deriving these estimates have been obtained by an empirical and by a direct minimisation approach.