MgY2 crystallizes in the orthorhombic Amm2 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), two equivalent Y(1), two equivalent Y(4), and four 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 three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(4)Y8Mg4 cuboctahedra, edges with four equivalent Y(3)Y6Mg6 cuboctahedra, edges with eight equivalent Y(2)Y8Mg4 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(4)Y8Mg4 cuboctahedra, faces with four equivalent Mg(1)Y8Mg4 cuboctahedra, faces with four equivalent Y(3)Y6Mg6 cuboctahedra, and faces with six equivalent Y(1)Y10Mg2 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Y(3), two equivalent Y(4), and four 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 three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Y(4)Y8Mg4 cuboctahedra, edges with four equivalent Y(2)Y8Mg4 cuboctahedra, edges with eight equivalent Y(1)Y10Mg2 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y10Mg2 cuboctahedra, faces with two equivalent Y(4)Y8Mg4 cuboctahedra, faces with four equivalent Mg(2)Y8Mg4 cuboctahedra, faces with four equivalent Y(2)Y8Mg4 cuboctahedra, and faces with six equivalent Y(3)Y6Mg6 cuboctahedra. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent Mg(1), two equivalent Y(1), two equivalent Y(2), two equivalent Y(3), and four equivalent Y(4) atoms to form YY10Mg2 cuboctahedra that share corners with six equivalent Y(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(3)Y6Mg6 cuboctahedra, corners with six equivalent Y(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(3)Y6Mg6 cuboctahedra, edges with three equivalent Y(2)Y8Mg4 cuboctahedra, edges with four equivalent Y(4)Y8Mg4 cuboctahedra, edges with eight equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y6Mg6 cuboctahedra, faces with two equivalent Y(2)Y8Mg4 cuboctahedra, faces with four equivalent Y(1)Y10Mg2 cuboctahedra, faces with four equivalent Y(4)Y8Mg4 cuboctahedra, and faces with six equivalent Mg(1)Y8Mg4 cuboctahedra. In the second Y site, Y(2) is bonded to four 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(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(3)Y6Mg6 cuboctahedra, corners with six equivalent Y(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(1)Y10Mg2 cuboctahedra, edges with three equivalent Y(3)Y6Mg6 cuboctahedra, edges with four equivalent Mg(2)Y8Mg4 cuboctahedra, edges with eight equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y10Mg2 cuboctahedra, faces with two equivalent Y(3)Y6Mg6 cuboctahedra, faces with four equivalent Mg(2)Y8Mg4 cuboctahedra, faces with four equivalent Y(2)Y8Mg4 cuboctahedra, and faces with six equivalent Y(4)Y8Mg4 cuboctahedra. In the third Y site, Y(3) is bonded to two equivalent Mg(2), four equivalent Mg(1), two equivalent Y(1), two equivalent Y(2), and two equivalent Y(3) atoms to form YY6Mg6 cuboctahedra that share corners with six equivalent Y(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(3)Y6Mg6 cuboctahedra, corners with six equivalent Y(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(1)Y10Mg2 cuboctahedra, edges with three equivalent Y(2)Y8Mg4 cuboctahedra, edges with four equivalent Mg(1)Y8Mg4 cuboctahedra, edges with eight equivalent Y(4)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y10Mg2 cuboctahedra, faces with two equivalent Y(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(4)Y8Mg4 cuboctahedra, faces with four equivalent Mg(1)Y8Mg4 cuboctahedra, faces with four equivalent Y(3)Y6Mg6 cuboctahedra, and faces with six equivalent Mg(2)Y8Mg4 cuboctahedra. In the fourth Y site, Y(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Y(2), two equivalent Y(4), and four 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 three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with four equivalent Y(1)Y10Mg2 cuboctahedra, edges with eight equivalent Y(3)Y6Mg6 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y6Mg6 cuboctahedra, faces with four equivalent Y(1)Y10Mg2 cuboctahedra, faces with four equivalent Y(4)Y8Mg4 cuboctahedra, and faces with six equivalent Y(2)Y8Mg4 cuboctahedra.
MgY2 crystallizes in the orthorhombic Amm2 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), two equivalent Y(1), two equivalent Y(4), and four 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 three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(4)Y8Mg4 cuboctahedra, edges with four equivalent Y(3)Y6Mg6 cuboctahedra, edges with eight equivalent Y(2)Y8Mg4 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(4)Y8Mg4 cuboctahedra, faces with four equivalent Mg(1)Y8Mg4 cuboctahedra, faces with four equivalent Y(3)Y6Mg6 cuboctahedra, and faces with six equivalent Y(1)Y10Mg2 cuboctahedra. Both Mg(1)-Mg(1) bond lengths are 3.51 Å. Both Mg(1)-Mg(2) bond lengths are 3.48 Å. Both Mg(1)-Y(1) bond lengths are 3.43 Å. Both Mg(1)-Y(4) bond lengths are 3.47 Å. All Mg(1)-Y(3) bond lengths are 3.45 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Y(3), two equivalent Y(4), and four 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 three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Y(4)Y8Mg4 cuboctahedra, edges with four equivalent Y(2)Y8Mg4 cuboctahedra, edges with eight equivalent Y(1)Y10Mg2 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y10Mg2 cuboctahedra, faces with two equivalent Y(4)Y8Mg4 cuboctahedra, faces with four equivalent Mg(2)Y8Mg4 cuboctahedra, faces with four equivalent Y(2)Y8Mg4 cuboctahedra, and faces with six equivalent Y(3)Y6Mg6 cuboctahedra. Both Mg(2)-Mg(2) bond lengths are 3.51 Å. Both Mg(2)-Y(3) bond lengths are 3.47 Å. Both Mg(2)-Y(4) bond lengths are 3.59 Å. All Mg(2)-Y(2) bond lengths are 3.46 Å. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent Mg(1), two equivalent Y(1), two equivalent Y(2), two equivalent Y(3), and four equivalent Y(4) atoms to form YY10Mg2 cuboctahedra that share corners with six equivalent Y(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(3)Y6Mg6 cuboctahedra, corners with six equivalent Y(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(3)Y6Mg6 cuboctahedra, edges with three equivalent Y(2)Y8Mg4 cuboctahedra, edges with four equivalent Y(4)Y8Mg4 cuboctahedra, edges with eight equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y6Mg6 cuboctahedra, faces with two equivalent Y(2)Y8Mg4 cuboctahedra, faces with four equivalent Y(1)Y10Mg2 cuboctahedra, faces with four equivalent Y(4)Y8Mg4 cuboctahedra, and faces with six equivalent Mg(1)Y8Mg4 cuboctahedra. Both Y(1)-Y(1) bond lengths are 3.51 Å. Both Y(1)-Y(2) bond lengths are 3.61 Å. Both Y(1)-Y(3) bond lengths are 3.43 Å. All Y(1)-Y(4) bond lengths are 3.46 Å. In the second Y site, Y(2) is bonded to four 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(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(3)Y6Mg6 cuboctahedra, corners with six equivalent Y(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(1)Y10Mg2 cuboctahedra, edges with three equivalent Y(3)Y6Mg6 cuboctahedra, edges with four equivalent Mg(2)Y8Mg4 cuboctahedra, edges with eight equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y10Mg2 cuboctahedra, faces with two equivalent Y(3)Y6Mg6 cuboctahedra, faces with four equivalent Mg(2)Y8Mg4 cuboctahedra, faces with four equivalent Y(2)Y8Mg4 cuboctahedra, and faces with six equivalent Y(4)Y8Mg4 cuboctahedra. Both Y(2)-Y(2) bond lengths are 3.51 Å. Both Y(2)-Y(3) bond lengths are 3.51 Å. Both Y(2)-Y(4) bond lengths are 3.52 Å. In the third Y site, Y(3) is bonded to two equivalent Mg(2), four equivalent Mg(1), two equivalent Y(1), two equivalent Y(2), and two equivalent Y(3) atoms to form YY6Mg6 cuboctahedra that share corners with six equivalent Y(1)Y10Mg2 cuboctahedra, corners with six equivalent Y(3)Y6Mg6 cuboctahedra, corners with six equivalent Y(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(1)Y10Mg2 cuboctahedra, edges with three equivalent Y(2)Y8Mg4 cuboctahedra, edges with four equivalent Mg(1)Y8Mg4 cuboctahedra, edges with eight equivalent Y(4)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y10Mg2 cuboctahedra, faces with two equivalent Y(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(4)Y8Mg4 cuboctahedra, faces with four equivalent Mg(1)Y8Mg4 cuboctahedra, faces with four equivalent Y(3)Y6Mg6 cuboctahedra, and faces with six equivalent Mg(2)Y8Mg4 cuboctahedra. Both Y(3)-Y(3) bond lengths are 3.51 Å. In the fourth Y site, Y(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Y(2), two equivalent Y(4), and four 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 three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with four equivalent Y(1)Y10Mg2 cuboctahedra, edges with eight equivalent Y(3)Y6Mg6 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y6Mg6 cuboctahedra, faces with four equivalent Y(1)Y10Mg2 cuboctahedra, faces with four equivalent Y(4)Y8Mg4 cuboctahedra, and faces with six equivalent Y(2)Y8Mg4 cuboctahedra. Both Y(4)-Y(4) bond lengths are 3.51 Å.