Mg6CeBi crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 2-coordinate geometry to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Ce(1), and two equivalent Bi(1) atoms. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ce(1) atoms to form distorted MgCe2Mg10 cuboctahedra that share corners with four equivalent Ce(1)Mg10Bi2 cuboctahedra, corners with six equivalent Mg(2)Ce2Mg10 cuboctahedra, edges with two equivalent Ce(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Ce(1)Mg10Bi2 cuboctahedra, and faces with six equivalent Bi(1)Ce2Mg10 cuboctahedra. In the third Mg site, Mg(3) is bonded in a 11-coordinate geometry to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Ce(1), and two equivalent Bi(1) atoms. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Bi(1) atoms to form distorted MgMg10Bi2 cuboctahedra that share corners with four equivalent Bi(1)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with two equivalent Bi(1)Ce2Mg10 cuboctahedra, edges with four equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Ce2Mg10 cuboctahedra, and faces with six equivalent Ce(1)Mg10Bi2 cuboctahedra. Ce(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Bi(1) atoms to form distorted CeMg10Bi2 cuboctahedra that share corners with four equivalent Mg(2)Ce2Mg10 cuboctahedra, corners with six equivalent Ce(1)Mg10Bi2 cuboctahedra, edges with two equivalent Mg(2)Ce2Mg10 cuboctahedra, edges with four equivalent Bi(1)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with two equivalent Ce(1)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Ce2Mg10 cuboctahedra, and faces with six equivalent Mg(4)Mg10Bi2 cuboctahedra. Bi(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ce(1) atoms to form distorted BiCe2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Mg10Bi2 cuboctahedra, corners with six equivalent Bi(1)Ce2Mg10 cuboctahedra, edges with two equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with four equivalent Ce(1)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Ce(1)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Ce2Mg10 cuboctahedra, and faces with six equivalent Mg(2)Ce2Mg10 cuboctahedra.
Mg6CeBi crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 2-coordinate geometry to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Ce(1), and two equivalent Bi(1) atoms. There is one shorter (3.33 Å) and one longer (3.48 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 3.16 Å. Both Mg(1)-Mg(4) bond lengths are 3.23 Å. There is one shorter (3.34 Å) and one longer (3.46 Å) Mg(1)-Ce(1) bond length. Both Mg(1)-Bi(1) bond lengths are 3.30 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ce(1) atoms to form distorted MgCe2Mg10 cuboctahedra that share corners with four equivalent Ce(1)Mg10Bi2 cuboctahedra, corners with six equivalent Mg(2)Ce2Mg10 cuboctahedra, edges with two equivalent Ce(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Ce(1)Mg10Bi2 cuboctahedra, and faces with six equivalent Bi(1)Ce2Mg10 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.26 Å. All Mg(2)-Mg(3) bond lengths are 3.19 Å. Both Mg(2)-Ce(1) bond lengths are 3.45 Å. In the third Mg site, Mg(3) is bonded in a 11-coordinate geometry to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Ce(1), and two equivalent Bi(1) atoms. The Mg(3)-Mg(3) bond length is 3.22 Å. There is one shorter (3.39 Å) and one longer (3.41 Å) Mg(3)-Mg(4) bond length. Both Mg(3)-Ce(1) bond lengths are 3.35 Å. There is one shorter (3.24 Å) and one longer (3.57 Å) Mg(3)-Bi(1) bond length. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Bi(1) atoms to form distorted MgMg10Bi2 cuboctahedra that share corners with four equivalent Bi(1)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with two equivalent Bi(1)Ce2Mg10 cuboctahedra, edges with four equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Ce2Mg10 cuboctahedra, and faces with six equivalent Ce(1)Mg10Bi2 cuboctahedra. Both Mg(4)-Bi(1) bond lengths are 3.45 Å. Ce(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Bi(1) atoms to form distorted CeMg10Bi2 cuboctahedra that share corners with four equivalent Mg(2)Ce2Mg10 cuboctahedra, corners with six equivalent Ce(1)Mg10Bi2 cuboctahedra, edges with two equivalent Mg(2)Ce2Mg10 cuboctahedra, edges with four equivalent Bi(1)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with two equivalent Ce(1)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Ce2Mg10 cuboctahedra, and faces with six equivalent Mg(4)Mg10Bi2 cuboctahedra. Both Ce(1)-Bi(1) bond lengths are 3.24 Å. Bi(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ce(1) atoms to form distorted BiCe2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Mg10Bi2 cuboctahedra, corners with six equivalent Bi(1)Ce2Mg10 cuboctahedra, edges with two equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with four equivalent Ce(1)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Ce(1)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Ce2Mg10 cuboctahedra, and faces with six equivalent Mg(2)Ce2Mg10 cuboctahedra.