MgY2 is beta-derived structured and crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), one Y(3), two equivalent Y(1), two equivalent Y(4), and three equivalent Y(2) atoms to form distorted MgY8Mg4 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(4)Y8Mg4 cuboctahedra, edges with two equivalent Y(2)Y7Mg5 cuboctahedra, edges with three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(4)Y8Mg4 cuboctahedra, edges with four equivalent Y(3)Y8Mg4 cuboctahedra, edges with six equivalent Y(1)Y9Mg3 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with three equivalent Mg(2)Y8Mg4 cuboctahedra, faces with three equivalent Y(4)Y8Mg4 cuboctahedra, faces with three equivalent Y(1)Y9Mg3 cuboctahedra, faces with four equivalent Y(3)Y8Mg4 cuboctahedra, and faces with five equivalent Y(2)Y7Mg5 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), one Y(1), two equivalent Y(2), two equivalent Y(4), and three equivalent Y(3) atoms to form distorted MgY8Mg4 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(4)Y8Mg4 cuboctahedra, edges with two equivalent Y(3)Y8Mg4 cuboctahedra, edges with three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Y(4)Y8Mg4 cuboctahedra, edges with four equivalent Y(1)Y9Mg3 cuboctahedra, edges with six equivalent Y(2)Y7Mg5 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with three equivalent Mg(1)Y8Mg4 cuboctahedra, faces with three equivalent Y(2)Y7Mg5 cuboctahedra, faces with three equivalent Y(4)Y8Mg4 cuboctahedra, faces with four equivalent Y(1)Y9Mg3 cuboctahedra, and faces with five equivalent Y(3)Y8Mg4 cuboctahedra. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded to one Mg(2), two equivalent Mg(1), two equivalent Y(1), two equivalent Y(2), two equivalent Y(3), and three equivalent Y(4) atoms to form YY9Mg3 cuboctahedra that share corners with six equivalent Y(2)Y7Mg5 cuboctahedra, corners with six equivalent Y(3)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y9Mg3 cuboctahedra, edges with two equivalent Y(4)Y8Mg4 cuboctahedra, edges with three equivalent Y(2)Y7Mg5 cuboctahedra, edges with three equivalent Y(3)Y8Mg4 cuboctahedra, edges with four equivalent Mg(2)Y8Mg4 cuboctahedra, edges with six equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y9Mg3 cuboctahedra, faces with three equivalent Mg(1)Y8Mg4 cuboctahedra, faces with three equivalent Y(2)Y7Mg5 cuboctahedra, faces with three equivalent Y(3)Y8Mg4 cuboctahedra, faces with four equivalent Mg(2)Y8Mg4 cuboctahedra, and faces with five equivalent Y(4)Y8Mg4 cuboctahedra. In the second Y site, Y(2) is bonded to two equivalent Mg(2), three equivalent Mg(1), one Y(4), two equivalent Y(1), two equivalent Y(2), and two equivalent Y(3) atoms to form YY7Mg5 cuboctahedra that share corners with six equivalent Y(2)Y7Mg5 cuboctahedra, corners with six equivalent Y(3)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y9Mg3 cuboctahedra, edges with two equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Y(3)Y8Mg4 cuboctahedra, edges with three equivalent Y(1)Y9Mg3 cuboctahedra, edges with four equivalent Y(4)Y8Mg4 cuboctahedra, edges with six equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(2)Y7Mg5 cuboctahedra, faces with three equivalent Mg(2)Y8Mg4 cuboctahedra, faces with three equivalent Y(3)Y8Mg4 cuboctahedra, faces with three equivalent Y(1)Y9Mg3 cuboctahedra, faces with four equivalent Y(4)Y8Mg4 cuboctahedra, and faces with five equivalent Mg(1)Y8Mg4 cuboctahedra. In the third Y site, Y(3) is bonded to one Mg(1), three equivalent Mg(2), two equivalent Y(1), two equivalent Y(2), two equivalent Y(3), and two equivalent Y(4) atoms to form YY8Mg4 cuboctahedra that share corners with six equivalent Y(2)Y7Mg5 cuboctahedra, corners with six equivalent Y(3)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y9Mg3 cuboctahedra, edges with two equivalent Mg(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(2)Y7Mg5 cuboctahedra, edges with three equivalent Y(1)Y9Mg3 cuboctahedra, edges with four equivalent Mg(1)Y8Mg4 cuboctahedra, edges with six equivalent Y(4)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y8Mg4 cuboctahedra, faces with three equivalent Y(2)Y7Mg5 cuboctahedra, faces with three equivalent Y(4)Y8Mg4 cuboctahedra, faces with three equivalent Y(1)Y9Mg3 cuboctahedra, faces with four equivalent Mg(1)Y8Mg4 cuboctahedra, and faces with five equivalent Mg(2)Y8Mg4 cuboctahedra. In the fourth Y site, Y(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), one Y(2), two equivalent Y(3), two equivalent Y(4), and three equivalent Y(1) atoms to form YY8Mg4 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(4)Y8Mg4 cuboctahedra, edges with two equivalent Y(1)Y9Mg3 cuboctahedra, edges with three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with four equivalent Y(2)Y7Mg5 cuboctahedra, edges with six equivalent Y(3)Y8Mg4 cuboctahedra, faces with two equivalent Y(4)Y8Mg4 cuboctahedra, faces with three equivalent Mg(1)Y8Mg4 cuboctahedra, faces with three equivalent Mg(2)Y8Mg4 cuboctahedra, faces with three equivalent Y(3)Y8Mg4 cuboctahedra, faces with four equivalent Y(2)Y7Mg5 cuboctahedra, and faces with five equivalent Y(1)Y9Mg3 cuboctahedra.
MgY2 is beta-derived structured and crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), one Y(3), two equivalent Y(1), two equivalent Y(4), and three equivalent Y(2) atoms to form distorted MgY8Mg4 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(4)Y8Mg4 cuboctahedra, edges with two equivalent Y(2)Y7Mg5 cuboctahedra, edges with three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(4)Y8Mg4 cuboctahedra, edges with four equivalent Y(3)Y8Mg4 cuboctahedra, edges with six equivalent Y(1)Y9Mg3 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with three equivalent Mg(2)Y8Mg4 cuboctahedra, faces with three equivalent Y(4)Y8Mg4 cuboctahedra, faces with three equivalent Y(1)Y9Mg3 cuboctahedra, faces with four equivalent Y(3)Y8Mg4 cuboctahedra, and faces with five equivalent Y(2)Y7Mg5 cuboctahedra. Both Mg(1)-Mg(1) bond lengths are 3.52 Å. Both Mg(1)-Mg(2) bond lengths are 3.36 Å. The Mg(1)-Y(3) bond length is 3.40 Å. Both Mg(1)-Y(1) bond lengths are 3.34 Å. Both Mg(1)-Y(4) bond lengths are 3.65 Å. There are two shorter (3.36 Å) and one longer (3.54 Å) Mg(1)-Y(2) bond length. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), one Y(1), two equivalent Y(2), two equivalent Y(4), and three equivalent Y(3) atoms to form distorted MgY8Mg4 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(4)Y8Mg4 cuboctahedra, edges with two equivalent Y(3)Y8Mg4 cuboctahedra, edges with three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Y(4)Y8Mg4 cuboctahedra, edges with four equivalent Y(1)Y9Mg3 cuboctahedra, edges with six equivalent Y(2)Y7Mg5 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with three equivalent Mg(1)Y8Mg4 cuboctahedra, faces with three equivalent Y(2)Y7Mg5 cuboctahedra, faces with three equivalent Y(4)Y8Mg4 cuboctahedra, faces with four equivalent Y(1)Y9Mg3 cuboctahedra, and faces with five equivalent Y(3)Y8Mg4 cuboctahedra. Both Mg(2)-Mg(2) bond lengths are 3.52 Å. The Mg(2)-Y(1) bond length is 3.79 Å. Both Mg(2)-Y(2) bond lengths are 3.46 Å. Both Mg(2)-Y(4) bond lengths are 3.39 Å. There are two shorter (3.44 Å) and one longer (3.49 Å) Mg(2)-Y(3) bond length. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded to one Mg(2), two equivalent Mg(1), two equivalent Y(1), two equivalent Y(2), two equivalent Y(3), and three equivalent Y(4) atoms to form YY9Mg3 cuboctahedra that share corners with six equivalent Y(2)Y7Mg5 cuboctahedra, corners with six equivalent Y(3)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y9Mg3 cuboctahedra, edges with two equivalent Y(4)Y8Mg4 cuboctahedra, edges with three equivalent Y(2)Y7Mg5 cuboctahedra, edges with three equivalent Y(3)Y8Mg4 cuboctahedra, edges with four equivalent Mg(2)Y8Mg4 cuboctahedra, edges with six equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y9Mg3 cuboctahedra, faces with three equivalent Mg(1)Y8Mg4 cuboctahedra, faces with three equivalent Y(2)Y7Mg5 cuboctahedra, faces with three equivalent Y(3)Y8Mg4 cuboctahedra, faces with four equivalent Mg(2)Y8Mg4 cuboctahedra, and faces with five equivalent Y(4)Y8Mg4 cuboctahedra. Both Y(1)-Y(1) bond lengths are 3.52 Å. Both Y(1)-Y(2) bond lengths are 3.51 Å. Both Y(1)-Y(3) bond lengths are 3.45 Å. There is one shorter (3.43 Å) and two longer (3.53 Å) Y(1)-Y(4) bond lengths. In the second Y site, Y(2) is bonded to two equivalent Mg(2), three equivalent Mg(1), one Y(4), two equivalent Y(1), two equivalent Y(2), and two equivalent Y(3) atoms to form YY7Mg5 cuboctahedra that share corners with six equivalent Y(2)Y7Mg5 cuboctahedra, corners with six equivalent Y(3)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y9Mg3 cuboctahedra, edges with two equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Y(3)Y8Mg4 cuboctahedra, edges with three equivalent Y(1)Y9Mg3 cuboctahedra, edges with four equivalent Y(4)Y8Mg4 cuboctahedra, edges with six equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(2)Y7Mg5 cuboctahedra, faces with three equivalent Mg(2)Y8Mg4 cuboctahedra, faces with three equivalent Y(3)Y8Mg4 cuboctahedra, faces with three equivalent Y(1)Y9Mg3 cuboctahedra, faces with four equivalent Y(4)Y8Mg4 cuboctahedra, and faces with five equivalent Mg(1)Y8Mg4 cuboctahedra. The Y(2)-Y(4) bond length is 3.47 Å. Both Y(2)-Y(2) bond lengths are 3.52 Å. Both Y(2)-Y(3) bond lengths are 3.46 Å. In the third Y site, Y(3) is bonded to one Mg(1), three equivalent Mg(2), two equivalent Y(1), two equivalent Y(2), two equivalent Y(3), and two equivalent Y(4) atoms to form YY8Mg4 cuboctahedra that share corners with six equivalent Y(2)Y7Mg5 cuboctahedra, corners with six equivalent Y(3)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y9Mg3 cuboctahedra, edges with two equivalent Mg(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(2)Y7Mg5 cuboctahedra, edges with three equivalent Y(1)Y9Mg3 cuboctahedra, edges with four equivalent Mg(1)Y8Mg4 cuboctahedra, edges with six equivalent Y(4)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y8Mg4 cuboctahedra, faces with three equivalent Y(2)Y7Mg5 cuboctahedra, faces with three equivalent Y(4)Y8Mg4 cuboctahedra, faces with three equivalent Y(1)Y9Mg3 cuboctahedra, faces with four equivalent Mg(1)Y8Mg4 cuboctahedra, and faces with five equivalent Mg(2)Y8Mg4 cuboctahedra. Both Y(3)-Y(3) bond lengths are 3.52 Å. Both Y(3)-Y(4) bond lengths are 3.56 Å. In the fourth Y site, Y(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), one Y(2), two equivalent Y(3), two equivalent Y(4), and three equivalent Y(1) atoms to form YY8Mg4 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(4)Y8Mg4 cuboctahedra, edges with two equivalent Y(1)Y9Mg3 cuboctahedra, edges with three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with four equivalent Y(2)Y7Mg5 cuboctahedra, edges with six equivalent Y(3)Y8Mg4 cuboctahedra, faces with two equivalent Y(4)Y8Mg4 cuboctahedra, faces with three equivalent Mg(1)Y8Mg4 cuboctahedra, faces with three equivalent Mg(2)Y8Mg4 cuboctahedra, faces with three equivalent Y(3)Y8Mg4 cuboctahedra, faces with four equivalent Y(2)Y7Mg5 cuboctahedra, and faces with five equivalent Y(1)Y9Mg3 cuboctahedra. Both Y(4)-Y(4) bond lengths are 3.52 Å.