Acta Cryst. (2006). E62, i91-i93  [ doi:10.1107/S1600536806009147 ]

Dipotassium heptafluorotantalate(V), -K₂TaF₇, at 509 K

V. Langer, L. Smrcok and M. Boca

Abstract: Upon heating to 509 K, monoclinic -K₂TaF₇ (P2₁/c) transforms to orthorhombic -K₂TaF₇ (Pnma) which is composed of discrete K⁺ cations and TaF₇^2- anions. In the anion, the Ta atom is sevenfold coordinated by F atoms, with the Ta-F distance varying from 1.88 (2) to 1.965 (19) Å. The two independent K⁺ cations are surrounded by F atoms positioned within 2.740 (17)-2.979 (10) and 2.989 (17)-3.15 (5) Å. Ta, both K and one of the four F atoms are located on a mirror plane, Wyckoff position 4c.

Online 15 March 2006

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