Mg2Y is Molybdenite structured and crystallizes in the hexagonal P6_3/mmc space group. Mg(1) is bonded to nine equivalent Mg(1) and three equivalent Y(1) atoms to form MgY3Mg9 cuboctahedra that share corners with six equivalent Y(1)Y6Mg6 cuboctahedra, corners with twelve equivalent Mg(1)Y3Mg9 cuboctahedra, edges with six equivalent Y(1)Y6Mg6 cuboctahedra, edges with twelve equivalent Mg(1)Y3Mg9 cuboctahedra, faces with seven equivalent Y(1)Y6Mg6 cuboctahedra, and faces with thirteen equivalent Mg(1)Y3Mg9 cuboctahedra. Y(1) is bonded to six equivalent Mg(1) and six equivalent Y(1) atoms to form YY6Mg6 cuboctahedra that share corners with six equivalent Y(1)Y6Mg6 cuboctahedra, corners with twelve equivalent Mg(1)Y3Mg9 cuboctahedra, edges with six equivalent Y(1)Y6Mg6 cuboctahedra, edges with twelve equivalent Mg(1)Y3Mg9 cuboctahedra, faces with six equivalent Y(1)Y6Mg6 cuboctahedra, and faces with fourteen equivalent Mg(1)Y3Mg9 cuboctahedra.
Mg2Y is Molybdenite structured and crystallizes in the hexagonal P6_3/mmc space group. Mg(1) is bonded to nine equivalent Mg(1) and three equivalent Y(1) atoms to form MgY3Mg9 cuboctahedra that share corners with six equivalent Y(1)Y6Mg6 cuboctahedra, corners with twelve equivalent Mg(1)Y3Mg9 cuboctahedra, edges with six equivalent Y(1)Y6Mg6 cuboctahedra, edges with twelve equivalent Mg(1)Y3Mg9 cuboctahedra, faces with seven equivalent Y(1)Y6Mg6 cuboctahedra, and faces with thirteen equivalent Mg(1)Y3Mg9 cuboctahedra. There are three shorter (3.26 Å) and six longer (3.33 Å) Mg(1)-Mg(1) bond lengths. All Mg(1)-Y(1) bond lengths are 3.45 Å. Y(1) is bonded to six equivalent Mg(1) and six equivalent Y(1) atoms to form YY6Mg6 cuboctahedra that share corners with six equivalent Y(1)Y6Mg6 cuboctahedra, corners with twelve equivalent Mg(1)Y3Mg9 cuboctahedra, edges with six equivalent Y(1)Y6Mg6 cuboctahedra, edges with twelve equivalent Mg(1)Y3Mg9 cuboctahedra, faces with six equivalent Y(1)Y6Mg6 cuboctahedra, and faces with fourteen equivalent Mg(1)Y3Mg9 cuboctahedra. All Y(1)-Y(1) bond lengths are 3.33 Å.