Mg14YSb crystallizes in the hexagonal P-6m2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Y(1) atoms to form MgY2Mg10 cuboctahedra that share corners with four equivalent Sb(1)Mg12 cuboctahedra, corners with six equivalent Mg(1)Y2Mg10 cuboctahedra, corners with eight equivalent Mg(2)Mg10Sb2 cuboctahedra, edges with two equivalent Y(1)Mg12 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(1)Y2Mg10 cuboctahedra, edges with eight equivalent Mg(3)YMg10Sb cuboctahedra, faces with two equivalent Mg(2)Mg10Sb2 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Y(1)Mg12 cuboctahedra, faces with four equivalent Mg(1)Y2Mg10 cuboctahedra, and faces with ten equivalent Mg(3)YMg10Sb cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4), four equivalent Mg(2), four equivalent Mg(3), and two equivalent Sb(1) atoms to form distorted MgMg10Sb2 cuboctahedra that share corners with four equivalent Y(1)Mg12 cuboctahedra, corners with six equivalent Mg(2)Mg10Sb2 cuboctahedra, corners with eight equivalent Mg(1)Y2Mg10 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 equivalent Mg(3)YMg10Sb cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(1)Y2Mg10 cuboctahedra, faces with two equivalent Sb(1)Mg12 cuboctahedra, faces with four equivalent Mg(2)Mg10Sb2 cuboctahedra, and faces with ten equivalent Mg(3)YMg10Sb cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), four equivalent Mg(3), one Y(1), and one Sb(1) atom to form distorted MgYMg10Sb cuboctahedra that share corners with four equivalent Mg(4)Mg12 cuboctahedra, corners with fourteen equivalent Mg(3)YMg10Sb cuboctahedra, edges with two equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Y(1)Mg12 cuboctahedra, edges with two equivalent Sb(1)Mg12 cuboctahedra, edges with four equivalent Mg(2)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(1)Y2Mg10 cuboctahedra, edges with four equivalent Mg(3)YMg10Sb cuboctahedra,  a faceface with one Y(1)Mg12 cuboctahedra,  a faceface with one Sb(1)Mg12 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with five equivalent Mg(2)Mg10Sb2 cuboctahedra, faces with five equivalent Mg(1)Y2Mg10 cuboctahedra, and faces with six equivalent Mg(3)YMg10Sb cuboctahedra. In the fourth Mg site, Mg(4) is bonded to three equivalent Mg(1), three equivalent Mg(2), and six equivalent Mg(3) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(4)Mg12 cuboctahedra, corners with twelve equivalent Mg(3)YMg10Sb cuboctahedra, edges with six equivalent Mg(2)Mg10Sb2 cuboctahedra, edges with six equivalent Mg(1)Y2Mg10 cuboctahedra, edges with six equivalent Mg(3)YMg10Sb cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with three equivalent Mg(2)Mg10Sb2 cuboctahedra, faces with three equivalent Mg(1)Y2Mg10 cuboctahedra, faces with three equivalent Y(1)Mg12 cuboctahedra, faces with three equivalent Sb(1)Mg12 cuboctahedra, and faces with six equivalent Mg(3)YMg10Sb cuboctahedra. Y(1) is bonded to six equivalent Mg(1) and six equivalent Mg(3) atoms to form YMg12 cuboctahedra that share corners with six equivalent Y(1)Mg12 cuboctahedra, corners with twelve equivalent Mg(2)Mg10Sb2 cuboctahedra, edges with six equivalent Mg(1)Y2Mg10 cuboctahedra, edges with twelve equivalent Mg(3)YMg10Sb cuboctahedra, faces with two equivalent Sb(1)Mg12 cuboctahedra, faces with six equivalent Mg(4)Mg12 cuboctahedra, faces with six equivalent Mg(1)Y2Mg10 cuboctahedra, and faces with six equivalent Mg(3)YMg10Sb cuboctahedra. Sb(1) is bonded to six equivalent Mg(2) and six equivalent Mg(3) atoms to form SbMg12 cuboctahedra that share corners with six equivalent Sb(1)Mg12 cuboctahedra, corners with twelve equivalent Mg(1)Y2Mg10 cuboctahedra, edges with six equivalent Mg(2)Mg10Sb2 cuboctahedra, edges with twelve equivalent Mg(3)YMg10Sb cuboctahedra, faces with two equivalent Y(1)Mg12 cuboctahedra, faces with six equivalent Mg(2)Mg10Sb2 cuboctahedra, faces with six equivalent Mg(4)Mg12 cuboctahedra, and faces with six equivalent Mg(3)YMg10Sb cuboctahedra.
Mg14YSb crystallizes in the hexagonal P-6m2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Y(1) atoms to form MgY2Mg10 cuboctahedra that share corners with four equivalent Sb(1)Mg12 cuboctahedra, corners with six equivalent Mg(1)Y2Mg10 cuboctahedra, corners with eight equivalent Mg(2)Mg10Sb2 cuboctahedra, edges with two equivalent Y(1)Mg12 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with four equivalent Mg(1)Y2Mg10 cuboctahedra, edges with eight equivalent Mg(3)YMg10Sb cuboctahedra, faces with two equivalent Mg(2)Mg10Sb2 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Y(1)Mg12 cuboctahedra, faces with four equivalent Mg(1)Y2Mg10 cuboctahedra, and faces with ten equivalent Mg(3)YMg10Sb cuboctahedra. Both Mg(1)-Mg(4) bond lengths are 3.20 Å. There are two shorter (3.17 Å) and two longer (3.31 Å) Mg(1)-Mg(1) bond lengths. All Mg(1)-Mg(3) bond lengths are 3.22 Å. Both Mg(1)-Y(1) bond lengths are 3.24 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4), four equivalent Mg(2), four equivalent Mg(3), and two equivalent Sb(1) atoms to form distorted MgMg10Sb2 cuboctahedra that share corners with four equivalent Y(1)Mg12 cuboctahedra, corners with six equivalent Mg(2)Mg10Sb2 cuboctahedra, corners with eight equivalent Mg(1)Y2Mg10 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 equivalent Mg(3)YMg10Sb cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Mg(1)Y2Mg10 cuboctahedra, faces with two equivalent Sb(1)Mg12 cuboctahedra, faces with four equivalent Mg(2)Mg10Sb2 cuboctahedra, and faces with ten equivalent Mg(3)YMg10Sb cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.25 Å. There are two shorter (3.20 Å) and two longer (3.28 Å) Mg(2)-Mg(2) bond lengths. All Mg(2)-Mg(3) bond lengths are 3.21 Å. Both Mg(2)-Sb(1) bond lengths are 3.24 Å. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), four equivalent Mg(3), one Y(1), and one Sb(1) atom to form distorted MgYMg10Sb cuboctahedra that share corners with four equivalent Mg(4)Mg12 cuboctahedra, corners with fourteen equivalent Mg(3)YMg10Sb cuboctahedra, edges with two equivalent Mg(4)Mg12 cuboctahedra, edges with two equivalent Y(1)Mg12 cuboctahedra, edges with two equivalent Sb(1)Mg12 cuboctahedra, edges with four equivalent Mg(2)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(1)Y2Mg10 cuboctahedra, edges with four equivalent Mg(3)YMg10Sb cuboctahedra,  a faceface with one Y(1)Mg12 cuboctahedra,  a faceface with one Sb(1)Mg12 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with five equivalent Mg(2)Mg10Sb2 cuboctahedra, faces with five equivalent Mg(1)Y2Mg10 cuboctahedra, and faces with six equivalent Mg(3)YMg10Sb cuboctahedra. Both Mg(3)-Mg(4) bond lengths are 3.24 Å. There are two shorter (3.23 Å) and two longer (3.25 Å) Mg(3)-Mg(3) bond lengths. The Mg(3)-Y(1) bond length is 3.23 Å. The Mg(3)-Sb(1) bond length is 3.21 Å. In the fourth Mg site, Mg(4) is bonded to three equivalent Mg(1), three equivalent Mg(2), and six equivalent Mg(3) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(4)Mg12 cuboctahedra, corners with twelve equivalent Mg(3)YMg10Sb cuboctahedra, edges with six equivalent Mg(2)Mg10Sb2 cuboctahedra, edges with six equivalent Mg(1)Y2Mg10 cuboctahedra, edges with six equivalent Mg(3)YMg10Sb cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with three equivalent Mg(2)Mg10Sb2 cuboctahedra, faces with three equivalent Mg(1)Y2Mg10 cuboctahedra, faces with three equivalent Y(1)Mg12 cuboctahedra, faces with three equivalent Sb(1)Mg12 cuboctahedra, and faces with six equivalent Mg(3)YMg10Sb cuboctahedra. Y(1) is bonded to six equivalent Mg(1) and six equivalent Mg(3) atoms to form YMg12 cuboctahedra that share corners with six equivalent Y(1)Mg12 cuboctahedra, corners with twelve equivalent Mg(2)Mg10Sb2 cuboctahedra, edges with six equivalent Mg(1)Y2Mg10 cuboctahedra, edges with twelve equivalent Mg(3)YMg10Sb cuboctahedra, faces with two equivalent Sb(1)Mg12 cuboctahedra, faces with six equivalent Mg(4)Mg12 cuboctahedra, faces with six equivalent Mg(1)Y2Mg10 cuboctahedra, and faces with six equivalent Mg(3)YMg10Sb cuboctahedra. Sb(1) is bonded to six equivalent Mg(2) and six equivalent Mg(3) atoms to form SbMg12 cuboctahedra that share corners with six equivalent Sb(1)Mg12 cuboctahedra, corners with twelve equivalent Mg(1)Y2Mg10 cuboctahedra, edges with six equivalent Mg(2)Mg10Sb2 cuboctahedra, edges with twelve equivalent Mg(3)YMg10Sb cuboctahedra, faces with two equivalent Y(1)Mg12 cuboctahedra, faces with six equivalent Mg(2)Mg10Sb2 cuboctahedra, faces with six equivalent Mg(4)Mg12 cuboctahedra, and faces with six equivalent Mg(3)YMg10Sb cuboctahedra.