Mg6FeSn crystallizes in the orthorhombic Amm2 space group. There are five 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 Fe(1), and two equivalent Sn(1) atoms to form distorted MgMg8Fe2Sn2 cuboctahedra that share corners with four equivalent Fe(1)Mg10Sn2 cuboctahedra; corners with four equivalent Sn(1)Mg10Fe2 cuboctahedra; corners with ten equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Fe(1)Mg10Sn2 cuboctahedra; edges with two equivalent Sn(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(3)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(2)Mg8Fe2Sn2 cuboctahedra; faces with two equivalent Mg(3)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with two equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; and faces with eight Mg(2,2)Mg8Fe2Sn2 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 Fe(1), and two equivalent Sn(1) atoms to form distorted MgMg8Fe2Sn2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Fe2 cuboctahedra; corners with ten Mg(2,2)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Mg(3)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg8Fe2Sn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with four equivalent Fe(1)Mg10Sn2 cuboctahedra; edges with four equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with two equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra; and faces with eight equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra. In the third 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 Fe(1), and two equivalent Sn(1) atoms to form distorted MgMg8Fe2Sn2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Fe2 cuboctahedra; corners with ten Mg(2,2)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Mg(3)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg8Fe2Sn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with four equivalent Fe(1)Mg10Sn2 cuboctahedra; edges with four equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with two equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra; and faces with eight equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra. In the fourth Mg site, Mg(3) is bonded to two equivalent Mg(4); four equivalent Mg(1); four Mg(2,2); and two equivalent Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with six equivalent Mg(3)Mg10Fe2 cuboctahedra; corners with eight Mg(2,2)Mg8Fe2Sn2 cuboctahedra; edges with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra; edges with four equivalent Fe(1)Mg10Sn2 cuboctahedra; edges with eight equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; faces with two equivalent Mg(3)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; faces with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra; and faces with six equivalent Sn(1)Mg10Fe2 cuboctahedra. In the fifth Mg site, Mg(4) is bonded in a distorted water-like geometry to two equivalent Mg(3); four equivalent Mg(1); four Mg(2,2); and two equivalent Sn(1) atoms. Fe(1) is bonded to two equivalent Mg(3); four equivalent Mg(1); four Mg(2,2); and two equivalent Sn(1) atoms to form FeMg10Sn2 cuboctahedra that share corners with four equivalent Sn(1)Mg10Fe2 cuboctahedra; corners with six equivalent Fe(1)Mg10Sn2 cuboctahedra; corners with eight equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Sn(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(3)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with eight Mg(2,2)Mg8Fe2Sn2 cuboctahedra; faces with two equivalent Mg(3)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with two equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; and faces with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra. Sn(1) is bonded to two equivalent Mg(4); four equivalent Mg(1); four Mg(2,2); and two equivalent Fe(1) atoms to form SnMg10Fe2 cuboctahedra that share corners with four equivalent Fe(1)Mg10Sn2 cuboctahedra; corners with six equivalent Sn(1)Mg10Fe2 cuboctahedra; corners with eight equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Fe(1)Mg10Sn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with eight Mg(2,2)Mg8Fe2Sn2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with two equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; faces with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra; and faces with six equivalent Mg(3)Mg10Fe2 cuboctahedra.
Mg6FeSn crystallizes in the orthorhombic Amm2 space group. There are five 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 Fe(1), and two equivalent Sn(1) atoms to form distorted MgMg8Fe2Sn2 cuboctahedra that share corners with four equivalent Fe(1)Mg10Sn2 cuboctahedra; corners with four equivalent Sn(1)Mg10Fe2 cuboctahedra; corners with ten equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Fe(1)Mg10Sn2 cuboctahedra; edges with two equivalent Sn(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(3)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(2)Mg8Fe2Sn2 cuboctahedra; faces with two equivalent Mg(3)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with two equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; and faces with eight Mg(2,2)Mg8Fe2Sn2 cuboctahedra. There is one shorter (3.10 Å) and one longer (3.13 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(2) bond lengths are 3.08 Å. Both Mg(1)-Mg(3) bond lengths are 3.08 Å. Both Mg(1)-Mg(4) bond lengths are 3.06 Å. There is one shorter (3.12 Å) and one longer (3.13 Å) Mg(1)-Fe(1) bond length. There is one shorter (3.11 Å) and one longer (3.13 Å) Mg(1)-Sn(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 Fe(1), and two equivalent Sn(1) atoms to form distorted MgMg8Fe2Sn2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Fe2 cuboctahedra; corners with ten Mg(2,2)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Mg(3)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg8Fe2Sn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with four equivalent Fe(1)Mg10Sn2 cuboctahedra; edges with four equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with two equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra; and faces with eight equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra. There is one shorter (2.94 Å) and one longer (3.29 Å) Mg(2)-Mg(2) bond length. There is one shorter (3.00 Å) and one longer (3.25 Å) Mg(2)-Mg(3) bond length. There is one shorter (3.08 Å) and one longer (3.17 Å) Mg(2)-Mg(4) bond length. Both Mg(2)-Fe(1) bond lengths are 3.01 Å. Both Mg(2)-Sn(1) bond lengths are 3.10 Å. In the third 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 Fe(1), and two equivalent Sn(1) atoms to form distorted MgMg8Fe2Sn2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Fe2 cuboctahedra; corners with ten Mg(2,2)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Mg(3)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg8Fe2Sn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with four equivalent Fe(1)Mg10Sn2 cuboctahedra; edges with four equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with two equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra; and faces with eight equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra. Both Mg(2)-Mg(1) bond lengths are 3.08 Å. There is one shorter (3.00 Å) and one longer (3.25 Å) Mg(2)-Mg(3) bond length. There is one shorter (3.08 Å) and one longer (3.17 Å) Mg(2)-Mg(4) bond length. Both Mg(2)-Fe(1) bond lengths are 3.01 Å. Both Mg(2)-Sn(1) bond lengths are 3.10 Å. In the fourth Mg site, Mg(3) is bonded to two equivalent Mg(4); four equivalent Mg(1); four Mg(2,2); and two equivalent Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with six equivalent Mg(3)Mg10Fe2 cuboctahedra; corners with eight Mg(2,2)Mg8Fe2Sn2 cuboctahedra; edges with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra; edges with four equivalent Fe(1)Mg10Sn2 cuboctahedra; edges with eight equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; faces with two equivalent Mg(3)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; faces with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra; and faces with six equivalent Sn(1)Mg10Fe2 cuboctahedra. Both Mg(3)-Mg(4) bond lengths are 3.12 Å. Both Mg(3)-Fe(1) bond lengths are 3.02 Å. In the fifth Mg site, Mg(4) is bonded in a distorted water-like geometry to two equivalent Mg(3); four equivalent Mg(1); four Mg(2,2); and two equivalent Sn(1) atoms. Both Mg(4)-Sn(1) bond lengths are 3.07 Å. Fe(1) is bonded to two equivalent Mg(3); four equivalent Mg(1); four Mg(2,2); and two equivalent Sn(1) atoms to form FeMg10Sn2 cuboctahedra that share corners with four equivalent Sn(1)Mg10Fe2 cuboctahedra; corners with six equivalent Fe(1)Mg10Sn2 cuboctahedra; corners with eight equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Sn(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(3)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with eight Mg(2,2)Mg8Fe2Sn2 cuboctahedra; faces with two equivalent Mg(3)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with two equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; and faces with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra. Both Fe(1)-Sn(1) bond lengths are 3.11 Å. Sn(1) is bonded to two equivalent Mg(4); four equivalent Mg(1); four Mg(2,2); and two equivalent Fe(1) atoms to form SnMg10Fe2 cuboctahedra that share corners with four equivalent Fe(1)Mg10Sn2 cuboctahedra; corners with six equivalent Sn(1)Mg10Fe2 cuboctahedra; corners with eight equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with two equivalent Fe(1)Mg10Sn2 cuboctahedra; edges with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; edges with eight Mg(2,2)Mg8Fe2Sn2 cuboctahedra; faces with two equivalent Fe(1)Mg10Sn2 cuboctahedra; faces with two equivalent Sn(1)Mg10Fe2 cuboctahedra; faces with four equivalent Mg(1)Mg8Fe2Sn2 cuboctahedra; faces with four Mg(2,2)Mg8Fe2Sn2 cuboctahedra; and faces with six equivalent Mg(3)Mg10Fe2 cuboctahedra.