MgSn2 crystallizes in the orthorhombic Cmcm space group. Mg(1) is bonded to four equivalent Sn(2) and six equivalent Sn(1) atoms to form distorted MgSn10 cuboctahedra that share corners with four equivalent Mg(1)Sn10 cuboctahedra, corners with six equivalent Sn(2)Mg4Sn2 cuboctahedra, corners with twelve equivalent Sn(1)Mg6Sn6 cuboctahedra,  an edgeedge with one Sn(1)Mg6Sn6 cuboctahedra, edges with three equivalent Sn(2)Mg4Sn2 cuboctahedra, edges with eight equivalent Mg(1)Sn10 cuboctahedra, faces with six equivalent Mg(1)Sn10 cuboctahedra, and faces with six equivalent Sn(1)Mg6Sn6 cuboctahedra. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to six equivalent Mg(1), two equivalent Sn(2), and four equivalent Sn(1) atoms to form distorted SnMg6Sn6 cuboctahedra that share corners with six equivalent Sn(1)Mg6Sn6 cuboctahedra, corners with twelve equivalent Mg(1)Sn10 cuboctahedra, corners with twelve equivalent Sn(2)Mg4Sn2 cuboctahedra,  an edgeedge with one Mg(1)Sn10 cuboctahedra, edges with seven equivalent Sn(2)Mg4Sn2 cuboctahedra, faces with two equivalent Sn(2)Mg4Sn2 cuboctahedra, faces with six equivalent Mg(1)Sn10 cuboctahedra, and faces with ten equivalent Sn(1)Mg6Sn6 cuboctahedra. In the second Sn site, Sn(2) is bonded to four equivalent Mg(1) and two equivalent Sn(1) atoms to form distorted SnMg4Sn2 cuboctahedra that share corners with two equivalent Sn(2)Mg4Sn2 cuboctahedra, corners with six equivalent Mg(1)Sn10 cuboctahedra, corners with twelve equivalent Sn(1)Mg6Sn6 cuboctahedra, edges with three equivalent Mg(1)Sn10 cuboctahedra, edges with six equivalent Sn(2)Mg4Sn2 cuboctahedra, edges with seven equivalent Sn(1)Mg6Sn6 cuboctahedra, and faces with two equivalent Sn(1)Mg6Sn6 cuboctahedra.
MgSn2 crystallizes in the orthorhombic Cmcm space group. Mg(1) is bonded to four equivalent Sn(2) and six equivalent Sn(1) atoms to form distorted MgSn10 cuboctahedra that share corners with four equivalent Mg(1)Sn10 cuboctahedra, corners with six equivalent Sn(2)Mg4Sn2 cuboctahedra, corners with twelve equivalent Sn(1)Mg6Sn6 cuboctahedra,  an edgeedge with one Sn(1)Mg6Sn6 cuboctahedra, edges with three equivalent Sn(2)Mg4Sn2 cuboctahedra, edges with eight equivalent Mg(1)Sn10 cuboctahedra, faces with six equivalent Mg(1)Sn10 cuboctahedra, and faces with six equivalent Sn(1)Mg6Sn6 cuboctahedra. There are two shorter (3.28 Å) and two longer (3.32 Å) Mg(1)-Sn(2) bond lengths. There are four shorter (3.32 Å) and two longer (3.33 Å) Mg(1)-Sn(1) bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to six equivalent Mg(1), two equivalent Sn(2), and four equivalent Sn(1) atoms to form distorted SnMg6Sn6 cuboctahedra that share corners with six equivalent Sn(1)Mg6Sn6 cuboctahedra, corners with twelve equivalent Mg(1)Sn10 cuboctahedra, corners with twelve equivalent Sn(2)Mg4Sn2 cuboctahedra,  an edgeedge with one Mg(1)Sn10 cuboctahedra, edges with seven equivalent Sn(2)Mg4Sn2 cuboctahedra, faces with two equivalent Sn(2)Mg4Sn2 cuboctahedra, faces with six equivalent Mg(1)Sn10 cuboctahedra, and faces with ten equivalent Sn(1)Mg6Sn6 cuboctahedra. Both Sn(1)-Sn(2) bond lengths are 3.31 Å. There are two shorter (3.33 Å) and two longer (3.36 Å) Sn(1)-Sn(1) bond lengths. In the second Sn site, Sn(2) is bonded to four equivalent Mg(1) and two equivalent Sn(1) atoms to form distorted SnMg4Sn2 cuboctahedra that share corners with two equivalent Sn(2)Mg4Sn2 cuboctahedra, corners with six equivalent Mg(1)Sn10 cuboctahedra, corners with twelve equivalent Sn(1)Mg6Sn6 cuboctahedra, edges with three equivalent Mg(1)Sn10 cuboctahedra, edges with six equivalent Sn(2)Mg4Sn2 cuboctahedra, edges with seven equivalent Sn(1)Mg6Sn6 cuboctahedra, and faces with two equivalent Sn(1)Mg6Sn6 cuboctahedra.