Mg14AlSb crystallizes in the hexagonal P-6m2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(4); four equivalent Mg(1); four Mg(3,3); and two equivalent Al(1) atoms to form MgMg10Al2 cuboctahedra that share corners with four equivalent Sb(1)Mg12 cuboctahedra; corners with six equivalent Mg(1)Mg10Al2 cuboctahedra; corners with eight Mg(2,2)Mg10Sb2 cuboctahedra; edges with two equivalent Al(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Al2 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight Mg(3,3)Mg10AlSb cuboctahedra; faces with two equivalent Mg(2)Mg10Sb2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Al(1)Mg12 cuboctahedra; faces with four equivalent Mg(1)Mg10Al2 cuboctahedra; and faces with ten Mg(3,3,3)Mg10AlSb cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4); four Mg(2,2); four Mg(3,3); and two equivalent Sb(1) atoms to form distorted MgMg10Sb2 cuboctahedra that share corners with four equivalent Al(1)Mg12 cuboctahedra; corners with six equivalent Mg(2)Mg10Sb2 cuboctahedra; corners with eight equivalent Mg(1)Mg10Al2 cuboctahedra; edges with two equivalent Sb(1)Mg12 cuboctahedra; edges with four Mg(2,2)Mg10Sb2 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight Mg(3,3)Mg10AlSb cuboctahedra; faces with two equivalent Mg(1)Mg10Al2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Sb(1)Mg12 cuboctahedra; faces with four Mg(2,2)Mg10Sb2 cuboctahedra; and faces with ten Mg(3,3,3)Mg10AlSb cuboctahedra. In the third Mg site, Mg(2) is bonded to two equivalent Mg(4); four equivalent Mg(2); four Mg(3,3); and two equivalent Sb(1) atoms to form distorted MgMg10Sb2 cuboctahedra that share corners with four equivalent Al(1)Mg12 cuboctahedra; corners with six equivalent Mg(2)Mg10Sb2 cuboctahedra; corners with eight equivalent Mg(1)Mg10Al2 cuboctahedra; edges with two equivalent Sb(1)Mg12 cuboctahedra; edges with four equivalent Mg(2)Mg10Sb2 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight Mg(3,3)Mg10AlSb cuboctahedra; faces with two equivalent Mg(1)Mg10Al2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Sb(1)Mg12 cuboctahedra; faces with four equivalent Mg(2)Mg10Sb2 cuboctahedra; and faces with ten Mg(3,3,3)Mg10AlSb cuboctahedra. In the fourth Mg site, Mg(3) is bonded to two equivalent Mg(1); two equivalent Mg(2); two equivalent Mg(4); four Mg(3,3); one Al(1); and one Sb(1) atom to form distorted MgMg10AlSb cuboctahedra that share corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with fourteen Mg(3,3,3)Mg10AlSb cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Al(1)Mg12 cuboctahedra; edges with two equivalent Sb(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Al2 cuboctahedra; edges with four Mg(3,3)Mg10AlSb cuboctahedra; edges with four equivalent Mg(2)Mg10Sb2 cuboctahedra;  a faceface with one Al(1)Mg12 cuboctahedra;  a faceface with one Sb(1)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with five equivalent Mg(1)Mg10Al2 cuboctahedra; faces with five Mg(2,2)Mg10Sb2 cuboctahedra; and faces with six Mg(3,3,3)Mg10AlSb cuboctahedra. In the fifth Mg site, Mg(3) is bonded to two equivalent Mg(1); two Mg(2,2); two equivalent Mg(4); four Mg(3,3); one Al(1); and one Sb(1) atom to form distorted MgMg10AlSb cuboctahedra that share corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with fourteen Mg(3,3,3)Mg10AlSb cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Al(1)Mg12 cuboctahedra; edges with two equivalent Sb(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Al2 cuboctahedra; edges with four Mg(3,3)Mg10AlSb cuboctahedra; edges with four Mg(2,2)Mg10Sb2 cuboctahedra;  a faceface with one Al(1)Mg12 cuboctahedra;  a faceface with one Sb(1)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with five equivalent Mg(1)Mg10Al2 cuboctahedra; faces with five Mg(2,2)Mg10Sb2 cuboctahedra; and faces with six Mg(3,3,3)Mg10AlSb cuboctahedra. In the sixth Mg site, Mg(3) is bonded to two equivalent Mg(1); two Mg(2,2); two equivalent Mg(4); four Mg(3,3); one Al(1); and one Sb(1) atom to form distorted MgMg10AlSb cuboctahedra that share corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with fourteen Mg(3,3,3)Mg10AlSb cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Al(1)Mg12 cuboctahedra; edges with two equivalent Sb(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Al2 cuboctahedra; edges with four Mg(3,3)Mg10AlSb cuboctahedra; edges with four Mg(2,2)Mg10Sb2 cuboctahedra;  a faceface with one Al(1)Mg12 cuboctahedra;  a faceface with one Sb(1)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with five equivalent Mg(1)Mg10Al2 cuboctahedra; faces with five Mg(2,2)Mg10Sb2 cuboctahedra; and faces with six Mg(3,3,3)Mg10AlSb cuboctahedra. In the seventh Mg site, Mg(4) is bonded to three equivalent Mg(1); three Mg(2,2); and six Mg(3,3,3) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(4)Mg12 cuboctahedra; corners with twelve Mg(3,3,3)Mg10AlSb cuboctahedra; edges with six equivalent Mg(1)Mg10Al2 cuboctahedra; edges with six Mg(3,3,3)Mg10AlSb cuboctahedra; edges with six Mg(2,2)Mg10Sb2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with three equivalent Mg(1)Mg10Al2 cuboctahedra; faces with three Mg(2,2)Mg10Sb2 cuboctahedra; faces with three equivalent Al(1)Mg12 cuboctahedra; faces with three equivalent Sb(1)Mg12 cuboctahedra; and faces with six Mg(3,3,3)Mg10AlSb cuboctahedra. Al(1) is bonded to six equivalent Mg(1) and six Mg(3,3,3) atoms to form AlMg12 cuboctahedra that share corners with six equivalent Al(1)Mg12 cuboctahedra; corners with twelve Mg(2,2)Mg10Sb2 cuboctahedra; edges with six equivalent Mg(1)Mg10Al2 cuboctahedra; edges with twelve Mg(3,3,3)Mg10AlSb cuboctahedra; faces with two equivalent Sb(1)Mg12 cuboctahedra; faces with six equivalent Mg(1)Mg10Al2 cuboctahedra; faces with six Mg(3,3,3)Mg10AlSb cuboctahedra; and faces with six equivalent Mg(4)Mg12 cuboctahedra. Sb(1) is bonded to six Mg(2,2) and six Mg(3,3,3) atoms to form SbMg12 cuboctahedra that share corners with six equivalent Sb(1)Mg12 cuboctahedra; corners with twelve equivalent Mg(1)Mg10Al2 cuboctahedra; edges with six Mg(2,2)Mg10Sb2 cuboctahedra; edges with twelve Mg(3,3,3)Mg10AlSb cuboctahedra; faces with two equivalent Al(1)Mg12 cuboctahedra; faces with six Mg(3,3,3)Mg10AlSb cuboctahedra; faces with six Mg(2,2)Mg10Sb2 cuboctahedra; and faces with six equivalent Mg(4)Mg12 cuboctahedra.
Mg14AlSb crystallizes in the hexagonal P-6m2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(4); four equivalent Mg(1); four Mg(3,3); and two equivalent Al(1) atoms to form MgMg10Al2 cuboctahedra that share corners with four equivalent Sb(1)Mg12 cuboctahedra; corners with six equivalent Mg(1)Mg10Al2 cuboctahedra; corners with eight Mg(2,2)Mg10Sb2 cuboctahedra; edges with two equivalent Al(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Al2 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight Mg(3,3)Mg10AlSb cuboctahedra; faces with two equivalent Mg(2)Mg10Sb2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Al(1)Mg12 cuboctahedra; faces with four equivalent Mg(1)Mg10Al2 cuboctahedra; and faces with ten Mg(3,3,3)Mg10AlSb cuboctahedra. Both Mg(1)-Mg(4) bond lengths are 3.16 Å. All Mg(1)-Mg(1) bond lengths are 3.18 Å. All Mg(1)-Mg(3,3) bond lengths are 3.14 Å. Both Mg(1)-Al(1) bond lengths are 3.18 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4); four Mg(2,2); four Mg(3,3); and two equivalent Sb(1) atoms to form distorted MgMg10Sb2 cuboctahedra that share corners with four equivalent Al(1)Mg12 cuboctahedra; corners with six equivalent Mg(2)Mg10Sb2 cuboctahedra; corners with eight equivalent Mg(1)Mg10Al2 cuboctahedra; edges with two equivalent Sb(1)Mg12 cuboctahedra; edges with four Mg(2,2)Mg10Sb2 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight Mg(3,3)Mg10AlSb cuboctahedra; faces with two equivalent Mg(1)Mg10Al2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Sb(1)Mg12 cuboctahedra; faces with four Mg(2,2)Mg10Sb2 cuboctahedra; and faces with ten Mg(3,3,3)Mg10AlSb cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.16 Å. There are two shorter (3.17 Å) and two longer (3.19 Å) Mg(2)-Mg(2,2) bond lengths. All Mg(2)-Mg(3,3) bond lengths are 3.18 Å. Both Mg(2)-Sb(1) bond lengths are 3.18 Å. In the third Mg site, Mg(2) is bonded to two equivalent Mg(4); four equivalent Mg(2); four Mg(3,3); and two equivalent Sb(1) atoms to form distorted MgMg10Sb2 cuboctahedra that share corners with four equivalent Al(1)Mg12 cuboctahedra; corners with six equivalent Mg(2)Mg10Sb2 cuboctahedra; corners with eight equivalent Mg(1)Mg10Al2 cuboctahedra; edges with two equivalent Sb(1)Mg12 cuboctahedra; edges with four equivalent Mg(2)Mg10Sb2 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight Mg(3,3)Mg10AlSb cuboctahedra; faces with two equivalent Mg(1)Mg10Al2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Sb(1)Mg12 cuboctahedra; faces with four equivalent Mg(2)Mg10Sb2 cuboctahedra; and faces with ten Mg(3,3,3)Mg10AlSb cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.16 Å. All Mg(2)-Mg(3,3) bond lengths are 3.18 Å. Both Mg(2)-Sb(1) bond lengths are 3.18 Å. In the fourth Mg site, Mg(3) is bonded to two equivalent Mg(1); two equivalent Mg(2); two equivalent Mg(4); four Mg(3,3); one Al(1); and one Sb(1) atom to form distorted MgMg10AlSb cuboctahedra that share corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with fourteen Mg(3,3,3)Mg10AlSb cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Al(1)Mg12 cuboctahedra; edges with two equivalent Sb(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Al2 cuboctahedra; edges with four Mg(3,3)Mg10AlSb cuboctahedra; edges with four equivalent Mg(2)Mg10Sb2 cuboctahedra;  a faceface with one Al(1)Mg12 cuboctahedra;  a faceface with one Sb(1)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with five equivalent Mg(1)Mg10Al2 cuboctahedra; faces with five Mg(2,2)Mg10Sb2 cuboctahedra; and faces with six Mg(3,3,3)Mg10AlSb cuboctahedra. Both Mg(3)-Mg(4) bond lengths are 3.18 Å. There are two shorter (3.17 Å) and two longer (3.19 Å) Mg(3)-Mg(3,3) bond lengths. The Mg(3)-Al(1) bond length is 3.14 Å. The Mg(3)-Sb(1) bond length is 3.19 Å. In the fifth Mg site, Mg(3) is bonded to two equivalent Mg(1); two Mg(2,2); two equivalent Mg(4); four Mg(3,3); one Al(1); and one Sb(1) atom to form distorted MgMg10AlSb cuboctahedra that share corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with fourteen Mg(3,3,3)Mg10AlSb cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Al(1)Mg12 cuboctahedra; edges with two equivalent Sb(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Al2 cuboctahedra; edges with four Mg(3,3)Mg10AlSb cuboctahedra; edges with four Mg(2,2)Mg10Sb2 cuboctahedra;  a faceface with one Al(1)Mg12 cuboctahedra;  a faceface with one Sb(1)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with five equivalent Mg(1)Mg10Al2 cuboctahedra; faces with five Mg(2,2)Mg10Sb2 cuboctahedra; and faces with six Mg(3,3,3)Mg10AlSb cuboctahedra. Both Mg(3)-Mg(4) bond lengths are 3.18 Å. There is one shorter (3.17 Å) and one longer (3.19 Å) Mg(3)-Mg(3) bond length. The Mg(3)-Al(1) bond length is 3.14 Å. The Mg(3)-Sb(1) bond length is 3.19 Å. In the sixth Mg site, Mg(3) is bonded to two equivalent Mg(1); two Mg(2,2); two equivalent Mg(4); four Mg(3,3); one Al(1); and one Sb(1) atom to form distorted MgMg10AlSb cuboctahedra that share corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with fourteen Mg(3,3,3)Mg10AlSb cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Al(1)Mg12 cuboctahedra; edges with two equivalent Sb(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Al2 cuboctahedra; edges with four Mg(3,3)Mg10AlSb cuboctahedra; edges with four Mg(2,2)Mg10Sb2 cuboctahedra;  a faceface with one Al(1)Mg12 cuboctahedra;  a faceface with one Sb(1)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with five equivalent Mg(1)Mg10Al2 cuboctahedra; faces with five Mg(2,2)Mg10Sb2 cuboctahedra; and faces with six Mg(3,3,3)Mg10AlSb cuboctahedra. Both Mg(3)-Mg(1) bond lengths are 3.14 Å. The Mg(3)-Mg(2) bond length is 3.18 Å. Both Mg(3)-Mg(4) bond lengths are 3.18 Å. The Mg(3)-Al(1) bond length is 3.14 Å. The Mg(3)-Sb(1) bond length is 3.19 Å. In the seventh Mg site, Mg(4) is bonded to three equivalent Mg(1); three Mg(2,2); and six Mg(3,3,3) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(4)Mg12 cuboctahedra; corners with twelve Mg(3,3,3)Mg10AlSb cuboctahedra; edges with six equivalent Mg(1)Mg10Al2 cuboctahedra; edges with six Mg(3,3,3)Mg10AlSb cuboctahedra; edges with six Mg(2,2)Mg10Sb2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with three equivalent Mg(1)Mg10Al2 cuboctahedra; faces with three Mg(2,2)Mg10Sb2 cuboctahedra; faces with three equivalent Al(1)Mg12 cuboctahedra; faces with three equivalent Sb(1)Mg12 cuboctahedra; and faces with six Mg(3,3,3)Mg10AlSb cuboctahedra. Al(1) is bonded to six equivalent Mg(1) and six Mg(3,3,3) atoms to form AlMg12 cuboctahedra that share corners with six equivalent Al(1)Mg12 cuboctahedra; corners with twelve Mg(2,2)Mg10Sb2 cuboctahedra; edges with six equivalent Mg(1)Mg10Al2 cuboctahedra; edges with twelve Mg(3,3,3)Mg10AlSb cuboctahedra; faces with two equivalent Sb(1)Mg12 cuboctahedra; faces with six equivalent Mg(1)Mg10Al2 cuboctahedra; faces with six Mg(3,3,3)Mg10AlSb cuboctahedra; and faces with six equivalent Mg(4)Mg12 cuboctahedra. Sb(1) is bonded to six Mg(2,2) and six Mg(3,3,3) atoms to form SbMg12 cuboctahedra that share corners with six equivalent Sb(1)Mg12 cuboctahedra; corners with twelve equivalent Mg(1)Mg10Al2 cuboctahedra; edges with six Mg(2,2)Mg10Sb2 cuboctahedra; edges with twelve Mg(3,3,3)Mg10AlSb cuboctahedra; faces with two equivalent Al(1)Mg12 cuboctahedra; faces with six Mg(3,3,3)Mg10AlSb cuboctahedra; faces with six Mg(2,2)Mg10Sb2 cuboctahedra; and faces with six equivalent Mg(4)Mg12 cuboctahedra.