Mg6ZrCr 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 Zr(1), and two equivalent Cr(1) atoms to form MgMg8Zr2Cr2 cuboctahedra that share corners with four equivalent Zr(1)Mg10Cr2 cuboctahedra, corners with four equivalent Cr(1)Mg10Zr2 cuboctahedra, corners with ten equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Zr(1)Mg10Cr2 cuboctahedra, edges with two equivalent Cr(1)Mg10Zr2 cuboctahedra, edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(3)Mg10Zr2 cuboctahedra, edges with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Mg10Zr2 cuboctahedra, faces with two equivalent Zr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, and faces with eight equivalent Mg(2)Mg8Zr2Cr2 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 Zr(1), and two equivalent Cr(1) atoms to form distorted MgMg8Zr2Cr2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with four equivalent Mg(3)Mg10Zr2 cuboctahedra, corners with ten equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(3)Mg10Zr2 cuboctahedra, edges with two equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with four equivalent Zr(1)Mg10Cr2 cuboctahedra, edges with four equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Mg10Zr2 cuboctahedra, faces with two equivalent Zr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, and faces with eight equivalent Mg(1)Mg8Zr2Cr2 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 Zr(1) atoms to form MgMg10Zr2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with six equivalent Mg(3)Mg10Zr2 cuboctahedra, corners with eight equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with four equivalent Zr(1)Mg10Cr2 cuboctahedra, edges with eight equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Mg10Zr2 cuboctahedra, faces with two equivalent Zr(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, and faces with six equivalent Cr(1)Mg10Zr2 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)Mg10Zr2 cuboctahedra, corners with six equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Mg(3)Mg10Zr2 cuboctahedra, edges with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with four equivalent Cr(1)Mg10Zr2 cuboctahedra, edges with eight equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Mg10Zr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, and faces with six equivalent Zr(1)Mg10Cr2 cuboctahedra. Zr(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Cr(1) atoms to form ZrMg10Cr2 cuboctahedra that share corners with four equivalent Cr(1)Mg10Zr2 cuboctahedra, corners with six equivalent Zr(1)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Cr(1)Mg10Zr2 cuboctahedra, edges with four equivalent Mg(3)Mg10Zr2 cuboctahedra, edges with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with eight equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, faces with two equivalent Mg(3)Mg10Zr2 cuboctahedra, faces with two equivalent Zr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with four equivalent Mg(2)Mg8Zr2Cr2 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 Zr(1) atoms to form CrMg10Zr2 cuboctahedra that share corners with four equivalent Zr(1)Mg10Cr2 cuboctahedra, corners with six equivalent Cr(1)Mg10Zr2 cuboctahedra, corners with eight equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Zr(1)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with eight equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Zr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, and faces with six equivalent Mg(3)Mg10Zr2 cuboctahedra.
Mg6ZrCr 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 Zr(1), and two equivalent Cr(1) atoms to form MgMg8Zr2Cr2 cuboctahedra that share corners with four equivalent Zr(1)Mg10Cr2 cuboctahedra, corners with four equivalent Cr(1)Mg10Zr2 cuboctahedra, corners with ten equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Zr(1)Mg10Cr2 cuboctahedra, edges with two equivalent Cr(1)Mg10Zr2 cuboctahedra, edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(3)Mg10Zr2 cuboctahedra, edges with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Mg10Zr2 cuboctahedra, faces with two equivalent Zr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, and faces with eight equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra. There is one shorter (3.06 Å) and one longer (3.17 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(2) bond lengths are 3.14 Å. Both Mg(1)-Mg(3) bond lengths are 3.10 Å. Both Mg(1)-Mg(4) bond lengths are 3.14 Å. There is one shorter (3.15 Å) and one longer (3.18 Å) Mg(1)-Zr(1) bond length. There is one shorter (3.12 Å) and one longer (3.20 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 Zr(1), and two equivalent Cr(1) atoms to form distorted MgMg8Zr2Cr2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with four equivalent Mg(3)Mg10Zr2 cuboctahedra, corners with ten equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(3)Mg10Zr2 cuboctahedra, edges with two equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with four equivalent Zr(1)Mg10Cr2 cuboctahedra, edges with four equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Mg10Zr2 cuboctahedra, faces with two equivalent Zr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, and faces with eight equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra. There is one shorter (3.07 Å) and one longer (3.17 Å) Mg(2)-Mg(2) bond length. There is one shorter (3.12 Å) and one longer (3.21 Å) Mg(2)-Mg(3) bond length. There is one shorter (3.06 Å) and one longer (3.27 Å) Mg(2)-Mg(4) bond length. Both Mg(2)-Zr(1) bond lengths are 3.11 Å. Both Mg(2)-Cr(1) bond lengths are 3.07 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 Zr(1) atoms to form MgMg10Zr2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with six equivalent Mg(3)Mg10Zr2 cuboctahedra, corners with eight equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with four equivalent Zr(1)Mg10Cr2 cuboctahedra, edges with eight equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Mg10Zr2 cuboctahedra, faces with two equivalent Zr(1)Mg10Cr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, and faces with six equivalent Cr(1)Mg10Zr2 cuboctahedra. Both Mg(3)-Mg(4) bond lengths are 3.12 Å. Both Mg(3)-Zr(1) bond lengths are 3.10 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)Mg10Zr2 cuboctahedra, corners with six equivalent Mg(4)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Mg(3)Mg10Zr2 cuboctahedra, edges with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, edges with four equivalent Cr(1)Mg10Zr2 cuboctahedra, edges with eight equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(3)Mg10Zr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, and faces with six equivalent Zr(1)Mg10Cr2 cuboctahedra. Both Mg(4)-Cr(1) bond lengths are 3.10 Å. Zr(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Cr(1) atoms to form ZrMg10Cr2 cuboctahedra that share corners with four equivalent Cr(1)Mg10Zr2 cuboctahedra, corners with six equivalent Zr(1)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Cr(1)Mg10Zr2 cuboctahedra, edges with four equivalent Mg(3)Mg10Zr2 cuboctahedra, edges with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with eight equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, faces with two equivalent Mg(3)Mg10Zr2 cuboctahedra, faces with two equivalent Zr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Cr2 cuboctahedra. Both Zr(1)-Cr(1) bond lengths are 3.12 Å. Cr(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Zr(1) atoms to form CrMg10Zr2 cuboctahedra that share corners with four equivalent Zr(1)Mg10Cr2 cuboctahedra, corners with six equivalent Cr(1)Mg10Zr2 cuboctahedra, corners with eight equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with two equivalent Zr(1)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, edges with eight equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra, faces with two equivalent Zr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Mg10Zr2 cuboctahedra, faces with four equivalent Mg(1)Mg8Zr2Cr2 cuboctahedra, faces with four equivalent Mg(2)Mg8Zr2Cr2 cuboctahedra, and faces with six equivalent Mg(3)Mg10Zr2 cuboctahedra.