MgY3 crystallizes in the hexagonal P-6m2 space group. Mg(1) is bonded to six equivalent Y(2) atoms to form distorted MgY6 cuboctahedra that share corners with twelve equivalent Y(1)Y12 cuboctahedra, corners with twelve equivalent Y(2)Y9Mg3 cuboctahedra, edges with six equivalent Mg(1)Y6 cuboctahedra, edges with twelve equivalent Y(2)Y9Mg3 cuboctahedra, and faces with two equivalent Y(1)Y12 cuboctahedra. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to six equivalent Y(1) and six equivalent Y(2) atoms to form YY12 cuboctahedra that share corners with six equivalent Y(1)Y12 cuboctahedra, corners with twelve equivalent Mg(1)Y6 cuboctahedra, edges with six equivalent Y(1)Y12 cuboctahedra, edges with twelve equivalent Y(2)Y9Mg3 cuboctahedra, faces with two equivalent Mg(1)Y6 cuboctahedra, faces with six equivalent Y(1)Y12 cuboctahedra, and faces with twelve equivalent Y(2)Y9Mg3 cuboctahedra. In the second Y site, Y(2) is bonded to three equivalent Mg(1), three equivalent Y(1), and six equivalent Y(2) atoms to form YY9Mg3 cuboctahedra that share corners with six equivalent Mg(1)Y6 cuboctahedra, corners with eighteen equivalent Y(2)Y9Mg3 cuboctahedra, edges with six equivalent Mg(1)Y6 cuboctahedra, edges with six equivalent Y(1)Y12 cuboctahedra, edges with six equivalent Y(2)Y9Mg3 cuboctahedra, faces with six equivalent Y(1)Y12 cuboctahedra, and faces with eight equivalent Y(2)Y9Mg3 cuboctahedra.
MgY3 crystallizes in the hexagonal P-6m2 space group. Mg(1) is bonded to six equivalent Y(2) atoms to form distorted MgY6 cuboctahedra that share corners with twelve equivalent Y(1)Y12 cuboctahedra, corners with twelve equivalent Y(2)Y9Mg3 cuboctahedra, edges with six equivalent Mg(1)Y6 cuboctahedra, edges with twelve equivalent Y(2)Y9Mg3 cuboctahedra, and faces with two equivalent Y(1)Y12 cuboctahedra. All Mg(1)-Y(2) bond lengths are 3.51 Å. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to six equivalent Y(1) and six equivalent Y(2) atoms to form YY12 cuboctahedra that share corners with six equivalent Y(1)Y12 cuboctahedra, corners with twelve equivalent Mg(1)Y6 cuboctahedra, edges with six equivalent Y(1)Y12 cuboctahedra, edges with twelve equivalent Y(2)Y9Mg3 cuboctahedra, faces with two equivalent Mg(1)Y6 cuboctahedra, faces with six equivalent Y(1)Y12 cuboctahedra, and faces with twelve equivalent Y(2)Y9Mg3 cuboctahedra. All Y(1)-Y(1) bond lengths are 3.54 Å. All Y(1)-Y(2) bond lengths are 3.53 Å. In the second Y site, Y(2) is bonded to three equivalent Mg(1), three equivalent Y(1), and six equivalent Y(2) atoms to form YY9Mg3 cuboctahedra that share corners with six equivalent Mg(1)Y6 cuboctahedra, corners with eighteen equivalent Y(2)Y9Mg3 cuboctahedra, edges with six equivalent Mg(1)Y6 cuboctahedra, edges with six equivalent Y(1)Y12 cuboctahedra, edges with six equivalent Y(2)Y9Mg3 cuboctahedra, faces with six equivalent Y(1)Y12 cuboctahedra, and faces with eight equivalent Y(2)Y9Mg3 cuboctahedra. All Y(2)-Y(2) bond lengths are 3.54 Å.