Electron-density distribution in a crystal of potassium tetrafluoronickelate, K2NiF4

Abstract

Dipotassium tetrafluoronickelate(II), K 2 NiF 4 , M r =212.90, tetragonal, I4/mmm, a=4.0130 (6), c=13.088 (2) A, V=210.78 (4) A 3 , Z=2, T=300 K, D x =3.36 Mg m -3 , Mo Kα, λ=0.7107 A, μ=656 mm -1 , F(000)=204, final R=0.018 for 698 unique reflections [I>2σ(I)]. Charge asphericity around the Ni atom caused by the splitting of 3d orbitals is clearly observed in the deformation density. Although the exact site symmetry at the Ni atom is D 4h , the local geometry around Ni is practically O h with Ni-F distances of 2.0065 (3) and 2.0062 (8) A