Materials Data on CsBe2F5 by Materials Project
CsBe2F5 crystallizes in the cubic P4_132 space group. The structure is three-dimensional. Cs1+ is bonded to twelve F1- atoms to form CsF12 cuboctahedra that share corners with twelve equivalent BeF4 tetrahedra, faces with six equivalent CsF12 cuboctahedra, and faces with two equivalent BeF4 tetrahedra. There are six shorter (3.29 Å) and six longer (3.49 Å) Cs–F bond lengths. Be2+ is bonded to four F1- atoms to form BeF4 tetrahedra that share corners with six equivalent CsF12 cuboctahedra, corners with three equivalent BeF4 tetrahedra, and a faceface with one CsF12 cuboctahedra. There is one shorter (1.50 Å) and three longer (1.59 Å) Be–F bond length. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to three equivalent Cs1+ and one Be2+ atom. In the second F1- site, F1- is bonded in a bent 120 degrees geometry to two equivalent Cs1+ and two equivalent Be2+ atoms.