Cs3AlF6 crystallizes in the cubic Fm-3m space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to twelve equivalent F(1) atoms to form distorted CsF12 cuboctahedra that share corners with twelve equivalent Cs(1)F12 cuboctahedra, faces with six equivalent Cs(1)F12 cuboctahedra, faces with four equivalent Cs(2)F6 octahedra, and faces with four equivalent Al(1)F6 octahedra. In the second Cs site, Cs(2) is bonded to six equivalent F(1) atoms to form CsF6 octahedra that share corners with six equivalent Al(1)F6 octahedra and faces with eight equivalent Cs(1)F12 cuboctahedra. The corner-sharing octahedra are not tilted. Al(1) is bonded to six equivalent F(1) atoms to form AlF6 octahedra that share corners with six equivalent Cs(2)F6 octahedra and faces with eight equivalent Cs(1)F12 cuboctahedra. The corner-sharing octahedra are not tilted. F(1) is bonded in a distorted single-bond geometry to one Cs(2), four equivalent Cs(1), and one Al(1) atom.
Cs3AlF6 crystallizes in the cubic Fm-3m space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to twelve equivalent F(1) atoms to form distorted CsF12 cuboctahedra that share corners with twelve equivalent Cs(1)F12 cuboctahedra, faces with six equivalent Cs(1)F12 cuboctahedra, faces with four equivalent Cs(2)F6 octahedra, and faces with four equivalent Al(1)F6 octahedra. All Cs(1)-F(1) bond lengths are 3.31 Å. In the second Cs site, Cs(2) is bonded to six equivalent F(1) atoms to form CsF6 octahedra that share corners with six equivalent Al(1)F6 octahedra and faces with eight equivalent Cs(1)F12 cuboctahedra. The corner-sharing octahedra are not tilted. All Cs(2)-F(1) bond lengths are 2.81 Å. Al(1) is bonded to six equivalent F(1) atoms to form AlF6 octahedra that share corners with six equivalent Cs(2)F6 octahedra and faces with eight equivalent Cs(1)F12 cuboctahedra. The corner-sharing octahedra are not tilted. All Al(1)-F(1) bond lengths are 1.82 Å. F(1) is bonded in a distorted single-bond geometry to one Cs(2), four equivalent Cs(1), and one Al(1) atom.