Preparation and Properties of Ammonium Hexachlorozirconate(IV) and Its Reaction with Gaseous Ammonia

Abstract

Ammonium hexachlorozirconate (NH₄)₂ZrCl₆ was prepared by the direct reaction of ZrCl₄ with NH₄Cl. The X-ray powder diffraction and the density measurements showed that it has a face-centered cubic lattice with a=10.127(2) Å and is isostructural with K₂PtCl₆. The hexachlorozirconate undergoes ammonolysis in gaseous ammonia at room temperature, forming ZrCl₃(NH₂)·xNH₃ and NH₄Cl. The ammonolysis product reverts to the initial (NH₄)₂ZrCl₆ on heating to 250 °C in the ammonia atmosphere. The hexachlorozirconate vaporizes at about 450 °C. The reaction of ZrCl₄ with gaseous ammonia was also studied in comparison with that of the hexachlorozirconate.