Mg6BiSb 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 Bi(1), and two equivalent Sb(1) atoms to form distorted MgMg8Bi2Sb2 cuboctahedra that share corners with two equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, corners with two equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with four equivalent Bi(1)Mg10Sb2 cuboctahedra, corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra, corners with ten equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, edges with two equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with two equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Mg10Bi2 cuboctahedra, faces with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, and faces with six equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(4), two equivalent Bi(1), and two equivalent Sb(1) atoms to form distorted MgMg4Bi2Sb2 cuboctahedra that share corners with two equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, corners with two equivalent Bi(1)Mg10Sb2 cuboctahedra, corners with four equivalent Mg(4)Mg10Bi2 cuboctahedra, corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra, corners with six equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with eight equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with two equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, faces with two equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra, faces with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, and faces with six equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(4), four equivalent Mg(1), and two equivalent Sb(1) atoms to form distorted MgMg6Sb2 cuboctahedra that share corners with two equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with four equivalent Mg(4)Mg10Bi2 cuboctahedra, corners with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra, corners with twelve equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with two equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, faces with two equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, faces with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, and faces with four equivalent Bi(1)Mg10Sb2 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 Bi(1) atoms to form distorted MgMg10Bi2 cuboctahedra that share corners with four equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with six equivalent Mg(4)Mg10Bi2 cuboctahedra, corners with eight equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with two equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with four equivalent Bi(1)Mg10Sb2 cuboctahedra, edges with eight equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra, faces with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, and faces with six equivalent Sb(1)Mg10Bi2 cuboctahedra. Bi(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Sb(1) atoms to form BiMg10Sb2 cuboctahedra that share corners with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra, corners with six equivalent Bi(1)Mg10Sb2 cuboctahedra, corners with eight equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, edges with two equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Mg10Bi2 cuboctahedra, faces with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, faces with four equivalent Mg(3)Mg6Sb2 cuboctahedra, and faces with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra. Sb(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Bi(1) atoms to form SbMg10Bi2 cuboctahedra that share corners with four equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with four equivalent Bi(1)Mg10Sb2 cuboctahedra, corners with six equivalent Sb(1)Mg10Bi2 cuboctahedra, corners with eight equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, corners with eight equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, edges with two equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Mg10Bi2 cuboctahedra, faces with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Bi2 cuboctahedra.
Mg6BiSb 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 Bi(1), and two equivalent Sb(1) atoms to form distorted MgMg8Bi2Sb2 cuboctahedra that share corners with two equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, corners with two equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with four equivalent Bi(1)Mg10Sb2 cuboctahedra, corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra, corners with ten equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, edges with two equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with two equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Mg10Bi2 cuboctahedra, faces with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, and faces with six equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra. There is one shorter (3.25 Å) and one longer (3.26 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(2) bond lengths are 3.25 Å. Both Mg(1)-Mg(3) bond lengths are 3.25 Å. Both Mg(1)-Mg(4) bond lengths are 3.24 Å. There is one shorter (3.26 Å) and one longer (3.29 Å) Mg(1)-Bi(1) bond length. There is one shorter (3.26 Å) and one longer (3.29 Å) Mg(1)-Sb(1) bond length. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(4), two equivalent Bi(1), and two equivalent Sb(1) atoms to form distorted MgMg4Bi2Sb2 cuboctahedra that share corners with two equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, corners with two equivalent Bi(1)Mg10Sb2 cuboctahedra, corners with four equivalent Mg(4)Mg10Bi2 cuboctahedra, corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra, corners with six equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with eight equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with two equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, faces with two equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra, faces with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, and faces with six equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra. There is one shorter (3.19 Å) and one longer (3.36 Å) Mg(2)-Mg(4) bond length. Both Mg(2)-Bi(1) bond lengths are 3.28 Å. Both Mg(2)-Sb(1) bond lengths are 3.26 Å. In the third Mg site, Mg(3) is bonded to two equivalent Mg(4), four equivalent Mg(1), and two equivalent Sb(1) atoms to form distorted MgMg6Sb2 cuboctahedra that share corners with two equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with four equivalent Mg(4)Mg10Bi2 cuboctahedra, corners with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra, corners with twelve equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with two equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, faces with two equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, faces with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, and faces with four equivalent Bi(1)Mg10Sb2 cuboctahedra. Both Mg(3)-Mg(4) bond lengths are 3.26 Å. Both Mg(3)-Sb(1) bond lengths are 3.26 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 Bi(1) atoms to form distorted MgMg10Bi2 cuboctahedra that share corners with four equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with six equivalent Mg(4)Mg10Bi2 cuboctahedra, corners with eight equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with two equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with four equivalent Bi(1)Mg10Sb2 cuboctahedra, edges with eight equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra, faces with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, and faces with six equivalent Sb(1)Mg10Bi2 cuboctahedra. Both Mg(4)-Bi(1) bond lengths are 3.29 Å. Bi(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Sb(1) atoms to form BiMg10Sb2 cuboctahedra that share corners with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, corners with four equivalent Sb(1)Mg10Bi2 cuboctahedra, corners with six equivalent Bi(1)Mg10Sb2 cuboctahedra, corners with eight equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, edges with two equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with two equivalent Sb(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Mg10Bi2 cuboctahedra, faces with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, faces with four equivalent Mg(3)Mg6Sb2 cuboctahedra, and faces with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra. Both Bi(1)-Sb(1) bond lengths are 3.26 Å. Sb(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Bi(1) atoms to form SbMg10Bi2 cuboctahedra that share corners with four equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with four equivalent Bi(1)Mg10Sb2 cuboctahedra, corners with six equivalent Sb(1)Mg10Bi2 cuboctahedra, corners with eight equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, corners with eight equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, edges with two equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with two equivalent Bi(1)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(2)Mg4Bi2Sb2 cuboctahedra, edges with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, faces with two equivalent Bi(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Mg10Bi2 cuboctahedra, faces with four equivalent Mg(1)Mg8Bi2Sb2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Bi2 cuboctahedra.