YMg3 is beta-derived structured and crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), six equivalent Mg(2), and four equivalent Y(1) atoms to form MgY4Mg8 cuboctahedra that share corners with four equivalent Y(1)Y2Mg10 cuboctahedra, corners with fourteen equivalent Mg(1)Y4Mg8 cuboctahedra, edges with two equivalent Mg(1)Y4Mg8 cuboctahedra, edges with four equivalent Y(1)Y2Mg10 cuboctahedra, edges with twelve equivalent Mg(2)Y3Mg9 cuboctahedra, faces with two equivalent Mg(1)Y4Mg8 cuboctahedra, faces with six equivalent Y(1)Y2Mg10 cuboctahedra, and faces with twelve equivalent Mg(2)Y3Mg9 cuboctahedra. In the second Mg site, Mg(2) is bonded to three equivalent Mg(1), six equivalent Mg(2), and three equivalent Y(1) atoms to form MgY3Mg9 cuboctahedra that share corners with eighteen equivalent Mg(2)Y3Mg9 cuboctahedra, edges with six equivalent Mg(2)Y3Mg9 cuboctahedra, edges with six equivalent Mg(1)Y4Mg8 cuboctahedra, edges with six equivalent Y(1)Y2Mg10 cuboctahedra, faces with six equivalent Mg(1)Y4Mg8 cuboctahedra, faces with six equivalent Y(1)Y2Mg10 cuboctahedra, and faces with eight equivalent Mg(2)Y3Mg9 cuboctahedra. Y(1) is bonded to four equivalent Mg(1), six equivalent Mg(2), and two equivalent Y(1) atoms to form YY2Mg10 cuboctahedra that share corners with four equivalent Mg(1)Y4Mg8 cuboctahedra, corners with fourteen equivalent Y(1)Y2Mg10 cuboctahedra, edges with two equivalent Y(1)Y2Mg10 cuboctahedra, edges with four equivalent Mg(1)Y4Mg8 cuboctahedra, edges with twelve equivalent Mg(2)Y3Mg9 cuboctahedra, faces with two equivalent Y(1)Y2Mg10 cuboctahedra, faces with six equivalent Mg(1)Y4Mg8 cuboctahedra, and faces with twelve equivalent Mg(2)Y3Mg9 cuboctahedra.
YMg3 is beta-derived structured and crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), six equivalent Mg(2), and four equivalent Y(1) atoms to form MgY4Mg8 cuboctahedra that share corners with four equivalent Y(1)Y2Mg10 cuboctahedra, corners with fourteen equivalent Mg(1)Y4Mg8 cuboctahedra, edges with two equivalent Mg(1)Y4Mg8 cuboctahedra, edges with four equivalent Y(1)Y2Mg10 cuboctahedra, edges with twelve equivalent Mg(2)Y3Mg9 cuboctahedra, faces with two equivalent Mg(1)Y4Mg8 cuboctahedra, faces with six equivalent Y(1)Y2Mg10 cuboctahedra, and faces with twelve equivalent Mg(2)Y3Mg9 cuboctahedra. Both Mg(1)-Mg(1) bond lengths are 3.28 Å. There are four shorter (3.32 Å) and two longer (3.37 Å) Mg(1)-Mg(2) bond lengths. There are two shorter (3.28 Å) and two longer (3.34 Å) Mg(1)-Y(1) bond lengths. In the second Mg site, Mg(2) is bonded to three equivalent Mg(1), six equivalent Mg(2), and three equivalent Y(1) atoms to form MgY3Mg9 cuboctahedra that share corners with eighteen equivalent Mg(2)Y3Mg9 cuboctahedra, edges with six equivalent Mg(2)Y3Mg9 cuboctahedra, edges with six equivalent Mg(1)Y4Mg8 cuboctahedra, edges with six equivalent Y(1)Y2Mg10 cuboctahedra, faces with six equivalent Mg(1)Y4Mg8 cuboctahedra, faces with six equivalent Y(1)Y2Mg10 cuboctahedra, and faces with eight equivalent Mg(2)Y3Mg9 cuboctahedra. There are two shorter (3.28 Å) and four longer (3.31 Å) Mg(2)-Mg(2) bond lengths. There is one shorter (3.34 Å) and two longer (3.36 Å) Mg(2)-Y(1) bond lengths. Y(1) is bonded to four equivalent Mg(1), six equivalent Mg(2), and two equivalent Y(1) atoms to form YY2Mg10 cuboctahedra that share corners with four equivalent Mg(1)Y4Mg8 cuboctahedra, corners with fourteen equivalent Y(1)Y2Mg10 cuboctahedra, edges with two equivalent Y(1)Y2Mg10 cuboctahedra, edges with four equivalent Mg(1)Y4Mg8 cuboctahedra, edges with twelve equivalent Mg(2)Y3Mg9 cuboctahedra, faces with two equivalent Y(1)Y2Mg10 cuboctahedra, faces with six equivalent Mg(1)Y4Mg8 cuboctahedra, and faces with twelve equivalent Mg(2)Y3Mg9 cuboctahedra. Both Y(1)-Y(1) bond lengths are 3.28 Å.