Mg5Cd crystallizes in the hexagonal P-6m2 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent Mg(2), six equivalent Mg(1), and three equivalent Cd(1) atoms to form distorted MgMg9Cd3 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra, corners with twelve equivalent Mg(1)Mg9Cd3 cuboctahedra, edges with six equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Mg(1)Mg9Cd3 cuboctahedra, edges with six equivalent Cd(1)Mg6Cd6 cuboctahedra,  a faceface with one Mg(3)Mg12 cuboctahedra, faces with six equivalent Mg(2)Mg12 cuboctahedra, faces with six equivalent Cd(1)Mg6Cd6 cuboctahedra, and faces with seven equivalent Mg(1)Mg9Cd3 cuboctahedra. In the second Mg site, Mg(2) is bonded to three equivalent Mg(1), three equivalent Mg(3), and six equivalent Mg(2) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Cd(1)Mg6Cd6 cuboctahedra, corners with twelve equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Mg(3)Mg12 cuboctahedra, edges with six equivalent Mg(1)Mg9Cd3 cuboctahedra,  a faceface with one Cd(1)Mg6Cd6 cuboctahedra, faces with six equivalent Mg(3)Mg12 cuboctahedra, faces with six equivalent Mg(1)Mg9Cd3 cuboctahedra, and faces with seven equivalent Mg(2)Mg12 cuboctahedra. In the third Mg site, Mg(3) is bonded to six equivalent Mg(2) and six equivalent Mg(3) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra, corners with twelve equivalent Mg(1)Mg9Cd3 cuboctahedra, edges with six equivalent Mg(3)Mg12 cuboctahedra, edges with twelve equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Mg(1)Mg9Cd3 cuboctahedra, faces with six equivalent Mg(3)Mg12 cuboctahedra, and faces with twelve equivalent Mg(2)Mg12 cuboctahedra. Cd(1) is bonded to six equivalent Mg(1) and six equivalent Cd(1) atoms to form CdMg6Cd6 cuboctahedra that share corners with six equivalent Cd(1)Mg6Cd6 cuboctahedra, corners with twelve equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Cd(1)Mg6Cd6 cuboctahedra, edges with twelve equivalent Mg(1)Mg9Cd3 cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with six equivalent Cd(1)Mg6Cd6 cuboctahedra, and faces with twelve equivalent Mg(1)Mg9Cd3 cuboctahedra.
Mg5Cd crystallizes in the hexagonal P-6m2 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent Mg(2), six equivalent Mg(1), and three equivalent Cd(1) atoms to form distorted MgMg9Cd3 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra, corners with twelve equivalent Mg(1)Mg9Cd3 cuboctahedra, edges with six equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Mg(1)Mg9Cd3 cuboctahedra, edges with six equivalent Cd(1)Mg6Cd6 cuboctahedra,  a faceface with one Mg(3)Mg12 cuboctahedra, faces with six equivalent Mg(2)Mg12 cuboctahedra, faces with six equivalent Cd(1)Mg6Cd6 cuboctahedra, and faces with seven equivalent Mg(1)Mg9Cd3 cuboctahedra. All Mg(1)-Mg(2) bond lengths are 3.23 Å. All Mg(1)-Mg(1) bond lengths are 3.15 Å. All Mg(1)-Cd(1) bond lengths are 3.19 Å. In the second Mg site, Mg(2) is bonded to three equivalent Mg(1), three equivalent Mg(3), and six equivalent Mg(2) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Cd(1)Mg6Cd6 cuboctahedra, corners with twelve equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Mg(3)Mg12 cuboctahedra, edges with six equivalent Mg(1)Mg9Cd3 cuboctahedra,  a faceface with one Cd(1)Mg6Cd6 cuboctahedra, faces with six equivalent Mg(3)Mg12 cuboctahedra, faces with six equivalent Mg(1)Mg9Cd3 cuboctahedra, and faces with seven equivalent Mg(2)Mg12 cuboctahedra. All Mg(2)-Mg(3) bond lengths are 3.22 Å. All Mg(2)-Mg(2) bond lengths are 3.15 Å. In the third Mg site, Mg(3) is bonded to six equivalent Mg(2) and six equivalent Mg(3) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra, corners with twelve equivalent Mg(1)Mg9Cd3 cuboctahedra, edges with six equivalent Mg(3)Mg12 cuboctahedra, edges with twelve equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Mg(1)Mg9Cd3 cuboctahedra, faces with six equivalent Mg(3)Mg12 cuboctahedra, and faces with twelve equivalent Mg(2)Mg12 cuboctahedra. All Mg(3)-Mg(3) bond lengths are 3.15 Å. Cd(1) is bonded to six equivalent Mg(1) and six equivalent Cd(1) atoms to form CdMg6Cd6 cuboctahedra that share corners with six equivalent Cd(1)Mg6Cd6 cuboctahedra, corners with twelve equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Cd(1)Mg6Cd6 cuboctahedra, edges with twelve equivalent Mg(1)Mg9Cd3 cuboctahedra, faces with two equivalent Mg(2)Mg12 cuboctahedra, faces with six equivalent Cd(1)Mg6Cd6 cuboctahedra, and faces with twelve equivalent Mg(1)Mg9Cd3 cuboctahedra. All Cd(1)-Cd(1) bond lengths are 3.15 Å.