Mg6FeBi crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Fe(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 Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with four equivalent Fe(1)Mg10Bi2 cuboctahedra, corners with six equivalent Mg(2)Mg10Fe2 cuboctahedra, edges with two equivalent Fe(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra, faces with two equivalent Fe(1)Mg10Bi2 cuboctahedra, and faces with six equivalent Bi(1)Mg10Fe2 cuboctahedra. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Fe(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)Mg10Fe2 cuboctahedra, corners with six equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with two equivalent Bi(1)Mg10Fe2 cuboctahedra, edges with four equivalent Mg(2)Mg10Fe2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra, faces with two equivalent Bi(1)Mg10Fe2 cuboctahedra, and faces with six equivalent Fe(1)Mg10Bi2 cuboctahedra. Fe(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Bi(1) atoms to form FeMg10Bi2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Fe2 cuboctahedra, corners with six equivalent Fe(1)Mg10Bi2 cuboctahedra, edges with two equivalent Mg(2)Mg10Fe2 cuboctahedra, edges with four equivalent Bi(1)Mg10Fe2 cuboctahedra, faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra, faces with two equivalent Fe(1)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Mg10Fe2 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 Fe(1) atoms to form BiMg10Fe2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Bi2 cuboctahedra, corners with six equivalent Bi(1)Mg10Fe2 cuboctahedra, edges with two equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with four equivalent Fe(1)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Fe(1)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Mg10Fe2 cuboctahedra, and faces with six equivalent Mg(2)Mg10Fe2 cuboctahedra.
Mg6FeBi crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Fe(1), and two equivalent Bi(1) atoms. There is one shorter (3.00 Å) and one longer (3.33 Å) Mg(1)-Mg(1) bond length. There is one shorter (3.14 Å) and one longer (3.18 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 3.08 Å. Both Mg(1)-Mg(4) bond lengths are 3.08 Å. There is one shorter (2.92 Å) and one longer (3.39 Å) Mg(1)-Fe(1) bond length. Both Mg(1)-Bi(1) bond lengths are 3.18 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 Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with four equivalent Fe(1)Mg10Bi2 cuboctahedra, corners with six equivalent Mg(2)Mg10Fe2 cuboctahedra, edges with two equivalent Fe(1)Mg10Bi2 cuboctahedra, edges with four equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra, faces with two equivalent Fe(1)Mg10Bi2 cuboctahedra, and faces with six equivalent Bi(1)Mg10Fe2 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.09 Å. All Mg(2)-Mg(3) bond lengths are 3.12 Å. Both Mg(2)-Fe(1) bond lengths are 3.17 Å. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Fe(1), and two equivalent Bi(1) atoms. There is one shorter (3.01 Å) and one longer (3.32 Å) Mg(3)-Mg(3) bond length. There is one shorter (3.14 Å) and one longer (3.18 Å) Mg(3)-Mg(4) bond length. Both Mg(3)-Fe(1) bond lengths are 3.01 Å. There is one shorter (3.04 Å) and one longer (3.27 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)Mg10Fe2 cuboctahedra, corners with six equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with two equivalent Bi(1)Mg10Fe2 cuboctahedra, edges with four equivalent Mg(2)Mg10Fe2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra, faces with two equivalent Bi(1)Mg10Fe2 cuboctahedra, and faces with six equivalent Fe(1)Mg10Bi2 cuboctahedra. Both Mg(4)-Bi(1) bond lengths are 3.16 Å. Fe(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Bi(1) atoms to form FeMg10Bi2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Fe2 cuboctahedra, corners with six equivalent Fe(1)Mg10Bi2 cuboctahedra, edges with two equivalent Mg(2)Mg10Fe2 cuboctahedra, edges with four equivalent Bi(1)Mg10Fe2 cuboctahedra, faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra, faces with two equivalent Fe(1)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Mg10Fe2 cuboctahedra, and faces with six equivalent Mg(4)Mg10Bi2 cuboctahedra. Both Fe(1)-Bi(1) bond lengths are 3.16 Å. Bi(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Fe(1) atoms to form BiMg10Fe2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Bi2 cuboctahedra, corners with six equivalent Bi(1)Mg10Fe2 cuboctahedra, edges with two equivalent Mg(4)Mg10Bi2 cuboctahedra, edges with four equivalent Fe(1)Mg10Bi2 cuboctahedra, faces with two equivalent Mg(4)Mg10Bi2 cuboctahedra, faces with two equivalent Fe(1)Mg10Bi2 cuboctahedra, faces with two equivalent Bi(1)Mg10Fe2 cuboctahedra, and faces with six equivalent Mg(2)Mg10Fe2 cuboctahedra.