Materials Data on KCrNiOF6 by Materials Project
KCrNiOF6 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. K1+ is bonded to two equivalent O2- and six F1- atoms to form KO2F6 hexagonal bipyramids that share edges with two equivalent KO2F6 hexagonal bipyramids, edges with two equivalent CrF6 octahedra, and edges with four equivalent NiF6 octahedra. Both K–O bond lengths are 2.91 Å. There are two shorter (2.64 Å) and four longer (2.71 Å) K–F bond lengths. Cr5+ is bonded to six F1- atoms to form CrF6 octahedra that share corners with two equivalent CrF6 octahedra, corners with four equivalent NiF6 octahedra, and edges with two equivalent KO2F6 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 38–40°. There is four shorter (1.93 Å) and two longer (2.01 Å) Cr–F bond length. Ni2+ is bonded to six F1- atoms to form NiF6 octahedra that share corners with two equivalent NiF6 octahedra, corners with four equivalent CrF6 octahedra, and edges with four equivalent KO2F6 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 40–45°. There are two shorter (2.03 Å) and four longer (2.04 Å) Ni–F bond lengths. O2- is bonded in a 3-coordinate geometry to two equivalent K1+ and one F1- atom. The O–F bond length is 2.36 Å. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a 3-coordinate geometry to one K1+, one Cr5+, and one Ni2+ atom. In the second F1- site, F1- is bonded in a 4-coordinate geometry to two equivalent K1+ and two equivalent Ni2+ atoms. In the third F1- site, F1- is bonded in a 2-coordinate geometry to two equivalent Cr5+ and one O2- atom.