MgLi2 crystallizes in the trigonal P-3m1 space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to three equivalent Li(2) and nine Li(1,1) atoms to form LiLi12 cuboctahedra that share corners with six equivalent Li(1)Li12 cuboctahedra; corners with six equivalent Li(2)Li9Mg3 cuboctahedra; corners with six equivalent Mg(1)Li3Mg9 cuboctahedra; edges with six equivalent Li(2)Li9Mg3 cuboctahedra; edges with twelve Li(1,1)Li12 cuboctahedra;  a faceface with one Mg(1)Li3Mg9 cuboctahedra; faces with seven equivalent Li(2)Li9Mg3 cuboctahedra; and faces with twelve Li(1,1)Li12 cuboctahedra. In the second Li site, Li(2) is bonded to three equivalent Li(1), six equivalent Li(2), and three equivalent Mg(1) atoms to form distorted LiLi9Mg3 cuboctahedra that share corners with six equivalent Li(1)Li12 cuboctahedra; corners with six equivalent Li(2)Li9Mg3 cuboctahedra; corners with six equivalent Mg(1)Li3Mg9 cuboctahedra; edges with six equivalent Li(1)Li12 cuboctahedra; edges with six equivalent Li(2)Li9Mg3 cuboctahedra; edges with six equivalent Mg(1)Li3Mg9 cuboctahedra; faces with six equivalent Li(2)Li9Mg3 cuboctahedra; faces with seven Li(1,1)Li12 cuboctahedra; and faces with seven equivalent Mg(1)Li3Mg9 cuboctahedra. In the third Li site, Li(1) is bonded to three equivalent Li(2) and nine Li(1,1) atoms to form LiLi12 cuboctahedra that share corners with six equivalent Li(1)Li12 cuboctahedra; corners with six equivalent Li(2)Li9Mg3 cuboctahedra; corners with six equivalent Mg(1)Li3Mg9 cuboctahedra; edges with six equivalent Li(2)Li9Mg3 cuboctahedra; edges with twelve Li(1,1)Li12 cuboctahedra;  a faceface with one Mg(1)Li3Mg9 cuboctahedra; faces with seven equivalent Li(2)Li9Mg3 cuboctahedra; and faces with twelve Li(1,1)Li12 cuboctahedra. Mg(1) is bonded to three equivalent Li(2) and nine equivalent Mg(1) atoms to form distorted MgLi3Mg9 cuboctahedra that share corners with six equivalent Li(1)Li12 cuboctahedra, corners with six equivalent Li(2)Li9Mg3 cuboctahedra, corners with six equivalent Mg(1)Li3Mg9 cuboctahedra, edges with six equivalent Li(2)Li9Mg3 cuboctahedra, edges with twelve equivalent Mg(1)Li3Mg9 cuboctahedra,  a faceface with one Li(1)Li12 cuboctahedra, faces with seven equivalent Li(2)Li9Mg3 cuboctahedra, and faces with twelve equivalent Mg(1)Li3Mg9 cuboctahedra.
MgLi2 crystallizes in the trigonal P-3m1 space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to three equivalent Li(2) and nine Li(1,1) atoms to form LiLi12 cuboctahedra that share corners with six equivalent Li(1)Li12 cuboctahedra; corners with six equivalent Li(2)Li9Mg3 cuboctahedra; corners with six equivalent Mg(1)Li3Mg9 cuboctahedra; edges with six equivalent Li(2)Li9Mg3 cuboctahedra; edges with twelve Li(1,1)Li12 cuboctahedra;  a faceface with one Mg(1)Li3Mg9 cuboctahedra; faces with seven equivalent Li(2)Li9Mg3 cuboctahedra; and faces with twelve Li(1,1)Li12 cuboctahedra. All Li(1)-Li(2) bond lengths are 3.08 Å. All Li(1)-Li(1,1) bond lengths are 3.11 Å. In the second Li site, Li(2) is bonded to three equivalent Li(1), six equivalent Li(2), and three equivalent Mg(1) atoms to form distorted LiLi9Mg3 cuboctahedra that share corners with six equivalent Li(1)Li12 cuboctahedra; corners with six equivalent Li(2)Li9Mg3 cuboctahedra; corners with six equivalent Mg(1)Li3Mg9 cuboctahedra; edges with six equivalent Li(1)Li12 cuboctahedra; edges with six equivalent Li(2)Li9Mg3 cuboctahedra; edges with six equivalent Mg(1)Li3Mg9 cuboctahedra; faces with six equivalent Li(2)Li9Mg3 cuboctahedra; faces with seven Li(1,1)Li12 cuboctahedra; and faces with seven equivalent Mg(1)Li3Mg9 cuboctahedra. All Li(2)-Li(2) bond lengths are 3.11 Å. All Li(2)-Mg(1) bond lengths are 3.07 Å. In the third Li site, Li(1) is bonded to three equivalent Li(2) and nine Li(1,1) atoms to form LiLi12 cuboctahedra that share corners with six equivalent Li(1)Li12 cuboctahedra; corners with six equivalent Li(2)Li9Mg3 cuboctahedra; corners with six equivalent Mg(1)Li3Mg9 cuboctahedra; edges with six equivalent Li(2)Li9Mg3 cuboctahedra; edges with twelve Li(1,1)Li12 cuboctahedra;  a faceface with one Mg(1)Li3Mg9 cuboctahedra; faces with seven equivalent Li(2)Li9Mg3 cuboctahedra; and faces with twelve Li(1,1)Li12 cuboctahedra. All Li(1)-Li(2) bond lengths are 3.08 Å. All Li(1)-Li(1) bond lengths are 3.11 Å. Mg(1) is bonded to three equivalent Li(2) and nine equivalent Mg(1) atoms to form distorted MgLi3Mg9 cuboctahedra that share corners with six equivalent Li(1)Li12 cuboctahedra, corners with six equivalent Li(2)Li9Mg3 cuboctahedra, corners with six equivalent Mg(1)Li3Mg9 cuboctahedra, edges with six equivalent Li(2)Li9Mg3 cuboctahedra, edges with twelve equivalent Mg(1)Li3Mg9 cuboctahedra,  a faceface with one Li(1)Li12 cuboctahedra, faces with seven equivalent Li(2)Li9Mg3 cuboctahedra, and faces with twelve equivalent Mg(1)Li3Mg9 cuboctahedra. There are six shorter (3.11 Å) and three longer (3.19 Å) Mg(1)-Mg(1) bond lengths.