CsMg14Si crystallizes in the hexagonal P-6m2 space group. Cs(1) is bonded to six equivalent Mg(2) and six equivalent Mg(3) atoms to form CsMg12 cuboctahedra that share corners with six equivalent Cs(1)Mg12 cuboctahedra, faces with two equivalent Si(1)Mg12 cuboctahedra, and faces with six equivalent Mg(4)Mg12 cuboctahedra. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Si(1) atoms. In the second Mg site, Mg(2) is bonded in a distorted linear geometry to two equivalent Cs(1) and two equivalent Mg(4) atoms. In the third Mg site, Mg(3) is bonded in a 10-coordinate geometry to one Cs(1), two equivalent Mg(1), two equivalent Mg(4), four equivalent Mg(3), and one Si(1) atom. In the fourth Mg site, Mg(4) is bonded to three equivalent Mg(1), three equivalent Mg(2), and six equivalent Mg(3) atoms to form distorted MgMg12 cuboctahedra that share corners with six equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with three equivalent Cs(1)Mg12 cuboctahedra, and faces with three equivalent Si(1)Mg12 cuboctahedra. Si(1) is bonded to six equivalent Mg(1) and six equivalent Mg(3) atoms to form SiMg12 cuboctahedra that share corners with six equivalent Si(1)Mg12 cuboctahedra, faces with two equivalent Cs(1)Mg12 cuboctahedra, and faces with six equivalent Mg(4)Mg12 cuboctahedra.
CsMg14Si crystallizes in the hexagonal P-6m2 space group. Cs(1) is bonded to six equivalent Mg(2) and six equivalent Mg(3) atoms to form CsMg12 cuboctahedra that share corners with six equivalent Cs(1)Mg12 cuboctahedra, faces with two equivalent Si(1)Mg12 cuboctahedra, and faces with six equivalent Mg(4)Mg12 cuboctahedra. All Cs(1)-Mg(2) bond lengths are 3.19 Å. All Cs(1)-Mg(3) bond lengths are 3.57 Å. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Si(1) atoms. Both Mg(1)-Mg(4) bond lengths are 3.41 Å. There are two shorter (3.11 Å) and two longer (3.27 Å) Mg(1)-Mg(1) bond lengths. All Mg(1)-Mg(3) bond lengths are 3.12 Å. Both Mg(1)-Si(1) bond lengths are 3.19 Å. In the second Mg site, Mg(2) is bonded in a distorted linear geometry to two equivalent Cs(1) and two equivalent Mg(4) atoms. Both Mg(2)-Mg(4) bond lengths are 3.26 Å. In the third Mg site, Mg(3) is bonded in a 10-coordinate geometry to one Cs(1), two equivalent Mg(1), two equivalent Mg(4), four equivalent Mg(3), and one Si(1) atom. Both Mg(3)-Mg(4) bond lengths are 3.22 Å. There are two shorter (3.16 Å) and two longer (3.22 Å) Mg(3)-Mg(3) bond lengths. The Mg(3)-Si(1) bond length is 3.09 Å. In the fourth Mg site, Mg(4) is bonded to three equivalent Mg(1), three equivalent Mg(2), and six equivalent Mg(3) atoms to form distorted MgMg12 cuboctahedra that share corners with six equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with three equivalent Cs(1)Mg12 cuboctahedra, and faces with three equivalent Si(1)Mg12 cuboctahedra. Si(1) is bonded to six equivalent Mg(1) and six equivalent Mg(3) atoms to form SiMg12 cuboctahedra that share corners with six equivalent Si(1)Mg12 cuboctahedra, faces with two equivalent Cs(1)Mg12 cuboctahedra, and faces with six equivalent Mg(4)Mg12 cuboctahedra.