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

Abstract

Enthalpies of solution of salts of MF62–(M = SiIV, TiIV, MnIV, or ReIV), reactions of anions of this type for M = OsIV, RuIV, and ReIV, 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 MF62– ions, enthalpies of formation of K2[MnF6], Rb2[MnF6], K2[ReF6], and several MF62– 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.