MgSn5 crystallizes in the hexagonal P-6m2 space group. Mg(1) is bonded to six equivalent Sn(1) atoms to form distorted MgSn6 cuboctahedra that share corners with twelve equivalent Sn(2)Sn12 cuboctahedra, edges with six equivalent Mg(1)Sn6 cuboctahedra, and faces with two equivalent Sn(2)Sn12 cuboctahedra. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 3-coordinate geometry to three equivalent Mg(1) and three equivalent Sn(2) atoms. In the second Sn site, Sn(2) is bonded to three equivalent Sn(1), three equivalent Sn(3), and six equivalent Sn(2) atoms to form distorted SnSn12 cuboctahedra that share corners with six equivalent Mg(1)Sn6 cuboctahedra, corners with twelve equivalent Sn(2)Sn12 cuboctahedra, edges with six equivalent Sn(2)Sn12 cuboctahedra, edges with six equivalent Sn(3)Sn12 cuboctahedra,  a faceface with one Mg(1)Sn6 cuboctahedra, faces with six equivalent Sn(3)Sn12 cuboctahedra, and faces with seven equivalent Sn(2)Sn12 cuboctahedra. In the third Sn site, Sn(3) is bonded to six equivalent Sn(2) and six equivalent Sn(3) atoms to form a mixture of corner, face, and edge-sharing SnSn12 cuboctahedra.
MgSn5 crystallizes in the hexagonal P-6m2 space group. Mg(1) is bonded to six equivalent Sn(1) atoms to form distorted MgSn6 cuboctahedra that share corners with twelve equivalent Sn(2)Sn12 cuboctahedra, edges with six equivalent Mg(1)Sn6 cuboctahedra, and faces with two equivalent Sn(2)Sn12 cuboctahedra. All Mg(1)-Sn(1) bond lengths are 3.26 Å. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 3-coordinate geometry to three equivalent Mg(1) and three equivalent Sn(2) atoms. All Sn(1)-Sn(2) bond lengths are 3.51 Å. In the second Sn site, Sn(2) is bonded to three equivalent Sn(1), three equivalent Sn(3), and six equivalent Sn(2) atoms to form distorted SnSn12 cuboctahedra that share corners with six equivalent Mg(1)Sn6 cuboctahedra, corners with twelve equivalent Sn(2)Sn12 cuboctahedra, edges with six equivalent Sn(2)Sn12 cuboctahedra, edges with six equivalent Sn(3)Sn12 cuboctahedra,  a faceface with one Mg(1)Sn6 cuboctahedra, faces with six equivalent Sn(3)Sn12 cuboctahedra, and faces with seven equivalent Sn(2)Sn12 cuboctahedra. All Sn(2)-Sn(3) bond lengths are 3.45 Å. All Sn(2)-Sn(2) bond lengths are 3.32 Å. In the third Sn site, Sn(3) is bonded to six equivalent Sn(2) and six equivalent Sn(3) atoms to form a mixture of corner, face, and edge-sharing SnSn12 cuboctahedra. All Sn(3)-Sn(3) bond lengths are 3.32 Å.