Materials Data on MgCrF5 by Materials Project
MgCrF5 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Mg2+ is bonded to seven F1- atoms to form distorted MgF7 pentagonal bipyramids that share corners with four equivalent CrF6 octahedra, edges with two equivalent CrF6 octahedra, and edges with two equivalent MgF7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 7–36°. There are a spread of Mg–F bond distances ranging from 1.93–2.48 Å. Cr3+ is bonded to six F1- atoms to form CrF6 octahedra that share corners with two equivalent CrF6 octahedra, corners with four equivalent MgF7 pentagonal bipyramids, and edges with two equivalent MgF7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 41°. There are a spread of Cr–F bond distances ranging from 1.92–1.98 Å. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted trigonal planar geometry to one Mg2+ and two equivalent Cr3+ atoms. In the second F1- site, F1- is bonded in a linear geometry to one Mg2+ and one Cr3+ atom. In the third F1- site, F1- is bonded in a 2-coordinate geometry to two equivalent Mg2+ and one Cr3+ atom.