Mg6YCr crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Y(1), and two equivalent Cr(1) atoms to form distorted MgY2Mg8Cr2 cuboctahedra that share corners with four equivalent Y(1)Mg10Cr2 cuboctahedra, corners with four equivalent Cr(1)Y2Mg10 cuboctahedra, corners with ten equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Y(1)Mg10Cr2 cuboctahedra, edges with two equivalent Cr(1)Y2Mg10 cuboctahedra, edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(3)Y2Mg10 cuboctahedra, edges with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Y2Mg10 cuboctahedra, faces with two equivalent Y(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Y2Mg10 cuboctahedra, faces with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, and faces with eight equivalent Mg(2)Y2Mg8Cr2 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Y(1), and two equivalent Cr(1) atoms to form distorted MgY2Mg8Cr2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with four equivalent Mg(3)Y2Mg10 cuboctahedra, corners with ten equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(3)Y2Mg10 cuboctahedra, edges with two equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with four equivalent Y(1)Mg10Cr2 cuboctahedra, edges with four equivalent Cr(1)Y2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Y2Mg10 cuboctahedra, faces with two equivalent Y(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Y2Mg10 cuboctahedra, faces with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, and faces with eight equivalent Mg(1)Y2Mg8Cr2 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Y(1) atoms to form MgY2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with six equivalent Mg(3)Y2Mg10 cuboctahedra, corners with eight equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with four equivalent Y(1)Mg10Cr2 cuboctahedra, edges with eight equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Y2Mg10 cuboctahedra, faces with two equivalent Y(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, and faces with six equivalent Cr(1)Y2Mg10 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Cr(1) atoms to form distorted MgMg10Cr2 cuboctahedra that share corners with four equivalent Mg(3)Y2Mg10 cuboctahedra, corners with six equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Mg(3)Y2Mg10 cuboctahedra, edges with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with four equivalent Cr(1)Y2Mg10 cuboctahedra, edges with eight equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Y2Mg10 cuboctahedra, faces with two equivalent Cr(1)Y2Mg10 cuboctahedra, faces with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, and faces with six equivalent Y(1)Mg10Cr2 cuboctahedra. Y(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Cr(1) atoms to form YMg10Cr2 cuboctahedra that share corners with four equivalent Cr(1)Y2Mg10 cuboctahedra, corners with six equivalent Y(1)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Cr(1)Y2Mg10 cuboctahedra, edges with four equivalent Mg(3)Y2Mg10 cuboctahedra, edges with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with eight equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, faces with two equivalent Mg(3)Y2Mg10 cuboctahedra, faces with two equivalent Y(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Y2Mg10 cuboctahedra, faces with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Cr2 cuboctahedra. Cr(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Y(1) atoms to form CrY2Mg10 cuboctahedra that share corners with four equivalent Y(1)Mg10Cr2 cuboctahedra, corners with six equivalent Cr(1)Y2Mg10 cuboctahedra, corners with eight equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Y(1)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with eight equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Y(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Y2Mg10 cuboctahedra, faces with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, and faces with six equivalent Mg(3)Y2Mg10 cuboctahedra.
Mg6YCr crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Y(1), and two equivalent Cr(1) atoms to form distorted MgY2Mg8Cr2 cuboctahedra that share corners with four equivalent Y(1)Mg10Cr2 cuboctahedra, corners with four equivalent Cr(1)Y2Mg10 cuboctahedra, corners with ten equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Y(1)Mg10Cr2 cuboctahedra, edges with two equivalent Cr(1)Y2Mg10 cuboctahedra, edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(3)Y2Mg10 cuboctahedra, edges with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Y2Mg10 cuboctahedra, faces with two equivalent Y(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Y2Mg10 cuboctahedra, faces with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, and faces with eight equivalent Mg(2)Y2Mg8Cr2 cuboctahedra. There is one shorter (3.15 Å) and one longer (3.28 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(2) bond lengths are 3.18 Å. Both Mg(1)-Mg(3) bond lengths are 3.15 Å. Both Mg(1)-Mg(4) bond lengths are 3.21 Å. Both Mg(1)-Y(1) bond lengths are 3.25 Å. There is one shorter (3.20 Å) and one longer (3.30 Å) Mg(1)-Cr(1) bond length. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Y(1), and two equivalent Cr(1) atoms to form distorted MgY2Mg8Cr2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with four equivalent Mg(3)Y2Mg10 cuboctahedra, corners with ten equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(3)Y2Mg10 cuboctahedra, edges with two equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with four equivalent Y(1)Mg10Cr2 cuboctahedra, edges with four equivalent Cr(1)Y2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Y2Mg10 cuboctahedra, faces with two equivalent Y(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Y2Mg10 cuboctahedra, faces with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, and faces with eight equivalent Mg(1)Y2Mg8Cr2 cuboctahedra. There is one shorter (3.07 Å) and one longer (3.35 Å) Mg(2)-Mg(2) bond length. There is one shorter (3.20 Å) and one longer (3.30 Å) Mg(2)-Mg(3) bond length. There is one shorter (3.15 Å) and one longer (3.34 Å) Mg(2)-Mg(4) bond length. Both Mg(2)-Y(1) bond lengths are 3.21 Å. Both Mg(2)-Cr(1) bond lengths are 3.13 Å. In the third Mg site, Mg(3) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Y(1) atoms to form MgY2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with six equivalent Mg(3)Y2Mg10 cuboctahedra, corners with eight equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with four equivalent Y(1)Mg10Cr2 cuboctahedra, edges with eight equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Y2Mg10 cuboctahedra, faces with two equivalent Y(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, and faces with six equivalent Cr(1)Y2Mg10 cuboctahedra. Both Mg(3)-Mg(4) bond lengths are 3.21 Å. Both Mg(3)-Y(1) bond lengths are 3.20 Å. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Cr(1) atoms to form distorted MgMg10Cr2 cuboctahedra that share corners with four equivalent Mg(3)Y2Mg10 cuboctahedra, corners with six equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Mg(3)Y2Mg10 cuboctahedra, edges with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, edges with four equivalent Cr(1)Y2Mg10 cuboctahedra, edges with eight equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Y2Mg10 cuboctahedra, faces with two equivalent Cr(1)Y2Mg10 cuboctahedra, faces with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, and faces with six equivalent Y(1)Mg10Cr2 cuboctahedra. Both Mg(4)-Cr(1) bond lengths are 3.17 Å. Y(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Cr(1) atoms to form YMg10Cr2 cuboctahedra that share corners with four equivalent Cr(1)Y2Mg10 cuboctahedra, corners with six equivalent Y(1)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Cr(1)Y2Mg10 cuboctahedra, edges with four equivalent Mg(3)Y2Mg10 cuboctahedra, edges with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with eight equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, faces with two equivalent Mg(3)Y2Mg10 cuboctahedra, faces with two equivalent Y(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Y2Mg10 cuboctahedra, faces with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Cr2 cuboctahedra. Both Y(1)-Cr(1) bond lengths are 3.21 Å. Cr(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Y(1) atoms to form CrY2Mg10 cuboctahedra that share corners with four equivalent Y(1)Mg10Cr2 cuboctahedra, corners with six equivalent Cr(1)Y2Mg10 cuboctahedra, corners with eight equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with two equivalent Y(1)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, edges with eight equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Y(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Y2Mg10 cuboctahedra, faces with four equivalent Mg(1)Y2Mg8Cr2 cuboctahedra, faces with four equivalent Mg(2)Y2Mg8Cr2 cuboctahedra, and faces with six equivalent Mg(3)Y2Mg10 cuboctahedra.