Materials Data on K3BeF5 by Materials Project
K3BeF5 crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.66–2.89 Å. In the second K1+ site, K1+ is bonded in a 2-coordinate geometry to ten F1- atoms. There are two shorter (2.73 Å) and eight longer (3.03 Å) K–F bond lengths. Be2+ is bonded in a tetrahedral geometry to four equivalent F1- atoms. All Be–F bond lengths are 1.57 Å. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted single-bond geometry to five K1+ and one Be2+ atom. In the second F1- site, F1- is bonded to six K1+ atoms to form corner-sharing FK6 octahedra. The corner-sharing octahedra tilt angles range from 0–31°.