LiMg5 crystallizes in the hexagonal P-6m2 space group. Li(1) is bonded to six equivalent Mg(1) atoms to form distorted LiMg6 cuboctahedra that share corners with twelve equivalent Mg(1)Li3Mg9 cuboctahedra; corners with twelve Mg(2,2)Mg12 cuboctahedra; edges with six equivalent Li(1)Mg6 cuboctahedra; edges with twelve equivalent Mg(1)Li3Mg9 cuboctahedra; and faces with two Mg(2,2)Mg12 cuboctahedra. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent Li(1), three equivalent Mg(2), and six equivalent Mg(1) atoms to form distorted MgLi3Mg9 cuboctahedra that share corners with six equivalent Li(1)Mg6 cuboctahedra, corners with six equivalent Mg(3)Mg12 cuboctahedra, corners with twelve equivalent Mg(1)Li3Mg9 cuboctahedra, edges with six equivalent Li(1)Mg6 cuboctahedra, edges with six equivalent Mg(1)Li3Mg9 cuboctahedra, edges with six equivalent Mg(2)Mg12 cuboctahedra,  a faceface with one Mg(3)Mg12 cuboctahedra, faces with six equivalent Mg(2)Mg12 cuboctahedra, and faces with seven equivalent Mg(1)Li3Mg9 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 Li(1)Mg6 cuboctahedra; corners with twelve Mg(2,2)Mg12 cuboctahedra; edges with six equivalent Mg(1)Li3Mg9 cuboctahedra; edges with six equivalent Mg(2)Mg12 cuboctahedra; edges with six equivalent Mg(3)Mg12 cuboctahedra;  a faceface with one Li(1)Mg6 cuboctahedra; faces with six equivalent Mg(1)Li3Mg9 cuboctahedra; faces with six equivalent Mg(3)Mg12 cuboctahedra; and faces with seven Mg(2,2)Mg12 cuboctahedra. In the third Mg site, Mg(3) is bonded to six Mg(2,2) 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)Li3Mg9 cuboctahedra; edges with six equivalent Mg(3)Mg12 cuboctahedra; edges with twelve Mg(2,2)Mg12 cuboctahedra; faces with two equivalent Mg(1)Li3Mg9 cuboctahedra; faces with six equivalent Mg(3)Mg12 cuboctahedra; and faces with twelve Mg(2,2)Mg12 cuboctahedra. In the fourth 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 Li(1)Mg6 cuboctahedra; corners with twelve Mg(2,2)Mg12 cuboctahedra; edges with six equivalent Mg(1)Li3Mg9 cuboctahedra; edges with six equivalent Mg(2)Mg12 cuboctahedra; edges with six equivalent Mg(3)Mg12 cuboctahedra;  a faceface with one Li(1)Mg6 cuboctahedra; faces with six equivalent Mg(1)Li3Mg9 cuboctahedra; faces with six equivalent Mg(3)Mg12 cuboctahedra; and faces with seven Mg(2,2)Mg12 cuboctahedra.
LiMg5 crystallizes in the hexagonal P-6m2 space group. Li(1) is bonded to six equivalent Mg(1) atoms to form distorted LiMg6 cuboctahedra that share corners with twelve equivalent Mg(1)Li3Mg9 cuboctahedra; corners with twelve Mg(2,2)Mg12 cuboctahedra; edges with six equivalent Li(1)Mg6 cuboctahedra; edges with twelve equivalent Mg(1)Li3Mg9 cuboctahedra; and faces with two Mg(2,2)Mg12 cuboctahedra. All Li(1)-Mg(1) bond lengths are 3.08 Å. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent Li(1), three equivalent Mg(2), and six equivalent Mg(1) atoms to form distorted MgLi3Mg9 cuboctahedra that share corners with six equivalent Li(1)Mg6 cuboctahedra, corners with six equivalent Mg(3)Mg12 cuboctahedra, corners with twelve equivalent Mg(1)Li3Mg9 cuboctahedra, edges with six equivalent Li(1)Mg6 cuboctahedra, edges with six equivalent Mg(1)Li3Mg9 cuboctahedra, edges with six equivalent Mg(2)Mg12 cuboctahedra,  a faceface with one Mg(3)Mg12 cuboctahedra, faces with six equivalent Mg(2)Mg12 cuboctahedra, and faces with seven equivalent Mg(1)Li3Mg9 cuboctahedra. All Mg(1)-Mg(2) bond lengths are 3.14 Å. All Mg(1)-Mg(1) bond lengths are 3.17 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 Li(1)Mg6 cuboctahedra; corners with twelve Mg(2,2)Mg12 cuboctahedra; edges with six equivalent Mg(1)Li3Mg9 cuboctahedra; edges with six equivalent Mg(2)Mg12 cuboctahedra; edges with six equivalent Mg(3)Mg12 cuboctahedra;  a faceface with one Li(1)Mg6 cuboctahedra; faces with six equivalent Mg(1)Li3Mg9 cuboctahedra; faces with six equivalent Mg(3)Mg12 cuboctahedra; and faces with seven Mg(2,2)Mg12 cuboctahedra. All Mg(2)-Mg(3) bond lengths are 3.13 Å. All Mg(2)-Mg(2) bond lengths are 3.17 Å. In the third Mg site, Mg(3) is bonded to six Mg(2,2) 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)Li3Mg9 cuboctahedra; edges with six equivalent Mg(3)Mg12 cuboctahedra; edges with twelve Mg(2,2)Mg12 cuboctahedra; faces with two equivalent Mg(1)Li3Mg9 cuboctahedra; faces with six equivalent Mg(3)Mg12 cuboctahedra; and faces with twelve Mg(2,2)Mg12 cuboctahedra. All Mg(3)-Mg(2) bond lengths are 3.13 Å. All Mg(3)-Mg(3) bond lengths are 3.17 Å. In the fourth 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 Li(1)Mg6 cuboctahedra; corners with twelve Mg(2,2)Mg12 cuboctahedra; edges with six equivalent Mg(1)Li3Mg9 cuboctahedra; edges with six equivalent Mg(2)Mg12 cuboctahedra; edges with six equivalent Mg(3)Mg12 cuboctahedra;  a faceface with one Li(1)Mg6 cuboctahedra; faces with six equivalent Mg(1)Li3Mg9 cuboctahedra; faces with six equivalent Mg(3)Mg12 cuboctahedra; and faces with seven Mg(2,2)Mg12 cuboctahedra. All Mg(2)-Mg(1) bond lengths are 3.14 Å. All Mg(2)-Mg(2) bond lengths are 3.17 Å.