Li3Mg5 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 10-coordinate geometry to two equivalent Mg(2) and eight equivalent Mg(1) atoms. In the second Li site, Li(2) is bonded in a distorted body-centered cubic geometry to eight equivalent Mg(1) atoms. There are two inequivalent Mg sites. In the first Mg site, Mg(2) is bonded to four equivalent Li(1) and eight equivalent Mg(1) atoms to form MgLi4Mg8 cuboctahedra that share corners with twelve equivalent Mg(2)Li4Mg8 cuboctahedra, edges with sixteen equivalent Mg(1)Li6Mg6 cuboctahedra, and faces with eight equivalent Mg(1)Li6Mg6 cuboctahedra. In the second Mg site, Mg(1) is bonded to two equivalent Li(2), four equivalent Li(1), two equivalent Mg(2), and four equivalent Mg(1) atoms to form distorted MgLi6Mg6 cuboctahedra that share corners with twelve equivalent Mg(1)Li6Mg6 cuboctahedra, edges with four equivalent Mg(2)Li4Mg8 cuboctahedra, edges with eight equivalent Mg(1)Li6Mg6 cuboctahedra, faces with two equivalent Mg(2)Li4Mg8 cuboctahedra, and faces with ten equivalent Mg(1)Li6Mg6 cuboctahedra.
Li3Mg5 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 10-coordinate geometry to two equivalent Mg(2) and eight equivalent Mg(1) atoms. Both Li(1)-Mg(2) bond lengths are 3.20 Å. All Li(1)-Mg(1) bond lengths are 3.06 Å. In the second Li site, Li(2) is bonded in a distorted body-centered cubic geometry to eight equivalent Mg(1) atoms. All Li(2)-Mg(1) bond lengths are 3.06 Å. There are two inequivalent Mg sites. In the first Mg site, Mg(2) is bonded to four equivalent Li(1) and eight equivalent Mg(1) atoms to form MgLi4Mg8 cuboctahedra that share corners with twelve equivalent Mg(2)Li4Mg8 cuboctahedra, edges with sixteen equivalent Mg(1)Li6Mg6 cuboctahedra, and faces with eight equivalent Mg(1)Li6Mg6 cuboctahedra. All Mg(2)-Mg(1) bond lengths are 3.06 Å. In the second Mg site, Mg(1) is bonded to two equivalent Li(2), four equivalent Li(1), two equivalent Mg(2), and four equivalent Mg(1) atoms to form distorted MgLi6Mg6 cuboctahedra that share corners with twelve equivalent Mg(1)Li6Mg6 cuboctahedra, edges with four equivalent Mg(2)Li4Mg8 cuboctahedra, edges with eight equivalent Mg(1)Li6Mg6 cuboctahedra, faces with two equivalent Mg(2)Li4Mg8 cuboctahedra, and faces with ten equivalent Mg(1)Li6Mg6 cuboctahedra. All Mg(1)-Mg(1) bond lengths are 3.20 Å.