Mg7Fe crystallizes in the hexagonal P-6m2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(3); four equivalent Mg(1); four Mg(2,2); and two equivalent Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with four equivalent Fe(1)Mg12 cuboctahedra; corners with fourteen equivalent Mg(1)Mg10Fe2 cuboctahedra; edges with two equivalent Fe(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with eight Mg(2,2)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Fe(1)Mg12 cuboctahedra; faces with six equivalent Mg(1)Mg10Fe2 cuboctahedra; and faces with ten Mg(2,2)Mg10Fe2 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with four equivalent Mg(3)Mg12 cuboctahedra; corners with fourteen Mg(2,2)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(3)Mg12 cuboctahedra; edges with four equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with four equivalent Fe(1)Mg12 cuboctahedra; edges with eight equivalent Mg(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Fe(1)Mg12 cuboctahedra; faces with six Mg(2,2)Mg10Fe2 cuboctahedra; and faces with ten equivalent Mg(1)Mg10Fe2 cuboctahedra. In the third Mg site, Mg(2) is bonded to two equivalent Mg(3); four equivalent Mg(1); four Mg(2,2); and two equivalent Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with four equivalent Mg(3)Mg12 cuboctahedra; corners with fourteen Mg(2,2)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(3)Mg12 cuboctahedra; edges with four Mg(2,2)Mg10Fe2 cuboctahedra; edges with four equivalent Fe(1)Mg12 cuboctahedra; edges with eight equivalent Mg(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Fe(1)Mg12 cuboctahedra; faces with six Mg(2,2)Mg10Fe2 cuboctahedra; and faces with ten equivalent Mg(1)Mg10Fe2 cuboctahedra. In the fourth Mg site, Mg(3) is bonded to six equivalent Mg(1) and six Mg(2,2) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra; corners with twelve Mg(2,2)Mg10Fe2 cuboctahedra; edges with six Mg(2,2)Mg10Fe2 cuboctahedra; edges with twelve equivalent Mg(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with six equivalent Mg(1)Mg10Fe2 cuboctahedra; faces with six Mg(2,2)Mg10Fe2 cuboctahedra; and faces with six equivalent Fe(1)Mg12 cuboctahedra. Fe(1) is bonded to six equivalent Mg(1) and six Mg(2,2) atoms to form FeMg12 cuboctahedra that share corners with six equivalent Fe(1)Mg12 cuboctahedra; corners with twelve equivalent Mg(1)Mg10Fe2 cuboctahedra; edges with six equivalent Mg(1)Mg10Fe2 cuboctahedra; edges with twelve Mg(2,2)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg12 cuboctahedra; faces with six equivalent Mg(1)Mg10Fe2 cuboctahedra; faces with six Mg(2,2)Mg10Fe2 cuboctahedra; and faces with six equivalent Mg(3)Mg12 cuboctahedra.
Mg7Fe crystallizes in the hexagonal P-6m2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(3); four equivalent Mg(1); four Mg(2,2); and two equivalent Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with four equivalent Fe(1)Mg12 cuboctahedra; corners with fourteen equivalent Mg(1)Mg10Fe2 cuboctahedra; edges with two equivalent Fe(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with eight Mg(2,2)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Fe(1)Mg12 cuboctahedra; faces with six equivalent Mg(1)Mg10Fe2 cuboctahedra; and faces with ten Mg(2,2)Mg10Fe2 cuboctahedra. Both Mg(1)-Mg(3) bond lengths are 3.03 Å. There are two shorter (3.06 Å) and two longer (3.07 Å) Mg(1)-Mg(1) bond lengths. All Mg(1)-Mg(2,2) bond lengths are 3.06 Å. Both Mg(1)-Fe(1) bond lengths are 3.07 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with four equivalent Mg(3)Mg12 cuboctahedra; corners with fourteen Mg(2,2)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(3)Mg12 cuboctahedra; edges with four equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with four equivalent Fe(1)Mg12 cuboctahedra; edges with eight equivalent Mg(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Fe(1)Mg12 cuboctahedra; faces with six Mg(2,2)Mg10Fe2 cuboctahedra; and faces with ten equivalent Mg(1)Mg10Fe2 cuboctahedra. Both Mg(2)-Mg(3) bond lengths are 3.07 Å. There are two shorter (2.89 Å) and two longer (3.25 Å) Mg(2)-Mg(2) bond lengths. Both Mg(2)-Fe(1) bond lengths are 2.97 Å. In the third Mg site, Mg(2) is bonded to two equivalent Mg(3); four equivalent Mg(1); four Mg(2,2); and two equivalent Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with four equivalent Mg(3)Mg12 cuboctahedra; corners with fourteen Mg(2,2)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(3)Mg12 cuboctahedra; edges with four Mg(2,2)Mg10Fe2 cuboctahedra; edges with four equivalent Fe(1)Mg12 cuboctahedra; edges with eight equivalent Mg(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Fe(1)Mg12 cuboctahedra; faces with six Mg(2,2)Mg10Fe2 cuboctahedra; and faces with ten equivalent Mg(1)Mg10Fe2 cuboctahedra. Both Mg(2)-Mg(3) bond lengths are 3.07 Å. There is one shorter (2.89 Å) and one longer (3.25 Å) Mg(2)-Mg(2) bond length. Both Mg(2)-Fe(1) bond lengths are 2.97 Å. In the fourth Mg site, Mg(3) is bonded to six equivalent Mg(1) and six Mg(2,2) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra; corners with twelve Mg(2,2)Mg10Fe2 cuboctahedra; edges with six Mg(2,2)Mg10Fe2 cuboctahedra; edges with twelve equivalent Mg(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with six equivalent Mg(1)Mg10Fe2 cuboctahedra; faces with six Mg(2,2)Mg10Fe2 cuboctahedra; and faces with six equivalent Fe(1)Mg12 cuboctahedra. Fe(1) is bonded to six equivalent Mg(1) and six Mg(2,2) atoms to form FeMg12 cuboctahedra that share corners with six equivalent Fe(1)Mg12 cuboctahedra; corners with twelve equivalent Mg(1)Mg10Fe2 cuboctahedra; edges with six equivalent Mg(1)Mg10Fe2 cuboctahedra; edges with twelve Mg(2,2)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg12 cuboctahedra; faces with six equivalent Mg(1)Mg10Fe2 cuboctahedra; faces with six Mg(2,2)Mg10Fe2 cuboctahedra; and faces with six equivalent Mg(3)Mg12 cuboctahedra.