Mg5Sn 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) and three equivalent Sn(1) atoms to form distorted MgMg3Sn3 cuboctahedra that share corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Mg(3)Mg12 cuboctahedra, corners with six equivalent Mg(1)Mg3Sn3 cuboctahedra, edges with six equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Mg(1)Mg3Sn3 cuboctahedra,  a faceface with one Mg(3)Mg12 cuboctahedra, and  a faceface with one Mg(1)Mg3Sn3 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 Mg(1)Mg3Sn3 cuboctahedra, corners with six equivalent Sn(1)Mg6 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)Mg3Sn3 cuboctahedra,  a faceface with one Sn(1)Mg6 cuboctahedra, faces with six equivalent Mg(3)Mg12 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)Mg3Sn3 cuboctahedra, edges with six equivalent Mg(3)Mg12 cuboctahedra, edges with twelve equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Mg(1)Mg3Sn3 cuboctahedra, faces with six equivalent Mg(3)Mg12 cuboctahedra, and faces with twelve equivalent Mg(2)Mg12 cuboctahedra. Sn(1) is bonded to six equivalent Mg(1) atoms to form distorted SnMg6 cuboctahedra that share corners with twelve equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Sn(1)Mg6 cuboctahedra, and faces with two equivalent Mg(2)Mg12 cuboctahedra.
Mg5Sn 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) and three equivalent Sn(1) atoms to form distorted MgMg3Sn3 cuboctahedra that share corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Mg(3)Mg12 cuboctahedra, corners with six equivalent Mg(1)Mg3Sn3 cuboctahedra, edges with six equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Mg(1)Mg3Sn3 cuboctahedra,  a faceface with one Mg(3)Mg12 cuboctahedra, and  a faceface with one Mg(1)Mg3Sn3 cuboctahedra. All Mg(1)-Mg(2) bond lengths are 3.23 Å. All Mg(1)-Sn(1) bond lengths are 3.16 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 Mg(1)Mg3Sn3 cuboctahedra, corners with six equivalent Sn(1)Mg6 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)Mg3Sn3 cuboctahedra,  a faceface with one Sn(1)Mg6 cuboctahedra, faces with six equivalent Mg(3)Mg12 cuboctahedra, and faces with seven equivalent Mg(2)Mg12 cuboctahedra. All Mg(2)-Mg(3) bond lengths are 3.18 Å. All Mg(2)-Mg(2) bond lengths are 3.25 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)Mg3Sn3 cuboctahedra, edges with six equivalent Mg(3)Mg12 cuboctahedra, edges with twelve equivalent Mg(2)Mg12 cuboctahedra, faces with two equivalent Mg(1)Mg3Sn3 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 3.25 Å. Sn(1) is bonded to six equivalent Mg(1) atoms to form distorted SnMg6 cuboctahedra that share corners with twelve equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Sn(1)Mg6 cuboctahedra, and faces with two equivalent Mg(2)Mg12 cuboctahedra.