Heat of formation of some alkali hexahalogenoniobates(IV) and potassium hexachlorotantalate(IV)

Abstract

Enthalpies of reaction are determined by solution calorimetry for the process 2AX(c)+ MX₄(c)→ A₂MX₆(c) where A₂MX₆ is K₂NbCl₆, Rb₂NbCl₆, Cs₂NbCl₆, Cs₂NbBr₆, and K₂TaCl₆. Heats of formation, ΔH°_f298, are determined for the chloro-complexes. The tantalum complex is more stable than K₂NbCl₆. There is no appreciable difference in the affinity exhibited by Nb^IV toward Cl^– and Br^– respectively.