MgFe12(OF)12 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(4), one F(4), and two equivalent F(1) atoms to form MgOF3 tetrahedra that share  a cornercorner with one Fe(2)O3F3 octahedra,  a cornercorner with one Fe(9)O3F3 octahedra, corners with two equivalent Fe(3)F6 octahedra, corners with two equivalent Mg(1)OF3 tetrahedra, and  an edgeedge with one Fe(3)F6 octahedra. The corner-sharing octahedral tilt angles range from 12-40°. There are twelve inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), two equivalent O(12), two equivalent O(2), and one F(9) atom to form FeO5F octahedra that share corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, and edges with two equivalent Fe(1)O5F octahedra. The corner-sharing octahedral tilt angles range from 48-56°. In the second Fe site, Fe(2) is bonded to one O(4), two equivalent O(1), one F(8), and two equivalent F(11) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(11)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra,  a cornercorner with one Mg(1)OF3 tetrahedra, and edges with two equivalent Fe(2)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-52°. In the third Fe site, Fe(3) is bonded to one F(10), one F(2), two equivalent F(1), and two equivalent F(12) atoms to form distorted FeF6 octahedra that share corners with two equivalent Fe(11)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Mg(1)OF3 tetrahedra, edges with two equivalent Fe(3)F6 octahedra, and  an edgeedge with one Mg(1)OF3 tetrahedra. The corner-sharing octahedral tilt angles range from 49-51°. In the fourth Fe site, Fe(4) is bonded to one O(1), two equivalent O(3), one F(5), and two equivalent F(3) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(8)O4F2 octahedra, corners with two equivalent Fe(1)O5F octahedra, and edges with two equivalent Fe(4)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-56°. In the fifth Fe site, Fe(5) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(4), and two equivalent F(3) atoms. In the sixth Fe site, Fe(6) is bonded in a 6-coordinate geometry to one O(2), two equivalent O(5), one F(6), and two equivalent F(2) atoms. In the seventh Fe site, Fe(7) is bonded to one O(10), two equivalent O(6), and two equivalent F(7) atoms to form distorted FeO3F2 square pyramids that share corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(11)O3F3 octahedra, and edges with two equivalent Fe(7)O3F2 square pyramids. The corner-sharing octahedral tilt angles range from 48-56°. In the eighth Fe site, Fe(8) is bonded to one O(5), one O(9), two equivalent O(7), and two equivalent F(5) atoms to form FeO4F2 octahedra that share corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, and edges with two equivalent Fe(8)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. In the ninth Fe site, Fe(9) is bonded to one O(11), two equivalent O(8), one F(4), and two equivalent F(6) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(11)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra,  a cornercorner with one Mg(1)OF3 tetrahedra, and edges with two equivalent Fe(9)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 51-53°. In the tenth Fe site, Fe(10) is bonded to one O(12), two equivalent O(9), one F(7), and two equivalent F(8) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(8)O4F2 octahedra, corners with two equivalent Fe(1)O5F octahedra, corners with two equivalent Fe(7)O3F2 square pyramids, and edges with two equivalent Fe(10)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-57°. In the eleventh Fe site, Fe(11) is bonded to one O(8), two equivalent O(10), one F(11), and two equivalent F(10) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(3)F6 octahedra, corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(9)O3F3 octahedra, corners with two equivalent Fe(7)O3F2 square pyramids, and edges with two equivalent Fe(11)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 49-51°. In the twelfth Fe site, Fe(12) is bonded to one O(7), two equivalent O(11), one F(12), and two equivalent F(9) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(3)F6 octahedra, corners with two equivalent Fe(9)O3F3 octahedra, corners with two equivalent Fe(8)O4F2 octahedra, corners with two equivalent Fe(1)O5F octahedra, and edges with two equivalent Fe(12)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Fe(4), one Fe(5), and two equivalent Fe(2) atoms to form corner-sharing OFe4 trigonal pyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(6) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(4) atoms. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Fe(2), and two equivalent Fe(5) atoms. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Fe(8) and two equivalent Fe(6) atoms. In the sixth O site, O(6) is bonded in a trigonal non-coplanar geometry to one Fe(5) and two equivalent Fe(7) atoms. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Fe(12) and two equivalent Fe(8) atoms. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Fe(11) and two equivalent Fe(9) atoms. In the ninth O site, O(9) is bonded in a trigonal planar geometry to one Fe(8) and two equivalent Fe(10) atoms. In the tenth O site, O(10) is bonded in a trigonal planar geometry to one Fe(7) and two equivalent Fe(11) atoms. In the eleventh O site, O(11) is bonded in a trigonal planar geometry to one Fe(9) and two equivalent Fe(12) atoms. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Fe(10) and two equivalent Fe(1) atoms. There are twelve inequivalent F sites. In the first F site, F(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Fe(3) atoms. In the second F site, F(2) is bonded in a 3-coordinate geometry to one Fe(3) and two equivalent Fe(6) atoms. In the third F site, F(3) is bonded in a 4-coordinate geometry to two equivalent Fe(4) and two equivalent Fe(5) atoms. In the fourth F site, F(4) is bonded in a bent 150 degrees geometry to one Mg(1) and one Fe(9) atom. In the fifth F site, F(5) is bonded in a distorted T-shaped geometry to one Fe(4) and two equivalent Fe(8) atoms. In the sixth F site, F(6) is bonded in a 3-coordinate geometry to one Fe(6) and two equivalent Fe(9) atoms. In the seventh F site, F(7) is bonded in a distorted trigonal planar geometry to one Fe(10) and two equivalent Fe(7) atoms. In the eighth F site, F(8) is bonded in a 3-coordinate geometry to one Fe(2) and two equivalent Fe(10) atoms. In the ninth F site, F(9) is bonded in a distorted trigonal planar geometry to one Fe(1) and two equivalent Fe(12) atoms. In the tenth F site, F(10) is bonded in a distorted T-shaped geometry to one Fe(3) and two equivalent Fe(11) atoms. In the eleventh F site, F(11) is bonded in a 3-coordinate geometry to one Fe(11) and two equivalent Fe(2) atoms. In the twelfth F site, F(12) is bonded in a trigonal planar geometry to one Fe(12) and two equivalent Fe(3) atoms.
MgFe12(OF)12 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(4), one F(4), and two equivalent F(1) atoms to form MgOF3 tetrahedra that share  a cornercorner with one Fe(2)O3F3 octahedra,  a cornercorner with one Fe(9)O3F3 octahedra, corners with two equivalent Fe(3)F6 octahedra, corners with two equivalent Mg(1)OF3 tetrahedra, and  an edgeedge with one Fe(3)F6 octahedra. The corner-sharing octahedral tilt angles range from 12-40°. The Mg(1)-O(4) bond length is 1.90 Å. The Mg(1)-F(4) bond length is 1.85 Å. Both Mg(1)-F(1) bond lengths are 1.97 Å. There are twelve inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), two equivalent O(12), two equivalent O(2), and one F(9) atom to form FeO5F octahedra that share corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, and edges with two equivalent Fe(1)O5F octahedra. The corner-sharing octahedral tilt angles range from 48-56°. The Fe(1)-O(3) bond length is 2.02 Å. Both Fe(1)-O(12) bond lengths are 2.02 Å. Both Fe(1)-O(2) bond lengths are 2.05 Å. The Fe(1)-F(9) bond length is 2.18 Å. In the second Fe site, Fe(2) is bonded to one O(4), two equivalent O(1), one F(8), and two equivalent F(11) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(11)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra,  a cornercorner with one Mg(1)OF3 tetrahedra, and edges with two equivalent Fe(2)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-52°. The Fe(2)-O(4) bond length is 2.00 Å. Both Fe(2)-O(1) bond lengths are 2.00 Å. The Fe(2)-F(8) bond length is 2.01 Å. Both Fe(2)-F(11) bond lengths are 2.08 Å. In the third Fe site, Fe(3) is bonded to one F(10), one F(2), two equivalent F(1), and two equivalent F(12) atoms to form distorted FeF6 octahedra that share corners with two equivalent Fe(11)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Mg(1)OF3 tetrahedra, edges with two equivalent Fe(3)F6 octahedra, and  an edgeedge with one Mg(1)OF3 tetrahedra. The corner-sharing octahedral tilt angles range from 49-51°. The Fe(3)-F(10) bond length is 2.09 Å. The Fe(3)-F(2) bond length is 1.99 Å. Both Fe(3)-F(1) bond lengths are 2.39 Å. Both Fe(3)-F(12) bond lengths are 2.00 Å. In the fourth Fe site, Fe(4) is bonded to one O(1), two equivalent O(3), one F(5), and two equivalent F(3) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(8)O4F2 octahedra, corners with two equivalent Fe(1)O5F octahedra, and edges with two equivalent Fe(4)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-56°. The Fe(4)-O(1) bond length is 2.03 Å. Both Fe(4)-O(3) bond lengths are 1.90 Å. The Fe(4)-F(5) bond length is 2.07 Å. Both Fe(4)-F(3) bond lengths are 2.25 Å. In the fifth Fe site, Fe(5) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(4), and two equivalent F(3) atoms. The Fe(5)-O(1) bond length is 2.10 Å. The Fe(5)-O(6) bond length is 1.95 Å. Both Fe(5)-O(4) bond lengths are 2.08 Å. Both Fe(5)-F(3) bond lengths are 2.41 Å. In the sixth Fe site, Fe(6) is bonded in a 6-coordinate geometry to one O(2), two equivalent O(5), one F(6), and two equivalent F(2) atoms. The Fe(6)-O(2) bond length is 1.89 Å. Both Fe(6)-O(5) bond lengths are 1.92 Å. The Fe(6)-F(6) bond length is 2.52 Å. Both Fe(6)-F(2) bond lengths are 2.29 Å. In the seventh Fe site, Fe(7) is bonded to one O(10), two equivalent O(6), and two equivalent F(7) atoms to form distorted FeO3F2 square pyramids that share corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(11)O3F3 octahedra, and edges with two equivalent Fe(7)O3F2 square pyramids. The corner-sharing octahedral tilt angles range from 48-56°. The Fe(7)-O(10) bond length is 1.92 Å. Both Fe(7)-O(6) bond lengths are 1.93 Å. Both Fe(7)-F(7) bond lengths are 2.10 Å. In the eighth Fe site, Fe(8) is bonded to one O(5), one O(9), two equivalent O(7), and two equivalent F(5) atoms to form FeO4F2 octahedra that share corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, and edges with two equivalent Fe(8)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. The Fe(8)-O(5) bond length is 2.04 Å. The Fe(8)-O(9) bond length is 2.01 Å. Both Fe(8)-O(7) bond lengths are 1.95 Å. Both Fe(8)-F(5) bond lengths are 2.18 Å. In the ninth Fe site, Fe(9) is bonded to one O(11), two equivalent O(8), one F(4), and two equivalent F(6) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(11)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra,  a cornercorner with one Mg(1)OF3 tetrahedra, and edges with two equivalent Fe(9)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 51-53°. The Fe(9)-O(11) bond length is 1.94 Å. Both Fe(9)-O(8) bond lengths are 2.01 Å. The Fe(9)-F(4) bond length is 2.00 Å. Both Fe(9)-F(6) bond lengths are 2.10 Å. In the tenth Fe site, Fe(10) is bonded to one O(12), two equivalent O(9), one F(7), and two equivalent F(8) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(8)O4F2 octahedra, corners with two equivalent Fe(1)O5F octahedra, corners with two equivalent Fe(7)O3F2 square pyramids, and edges with two equivalent Fe(10)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-57°. The Fe(10)-O(12) bond length is 1.89 Å. Both Fe(10)-O(9) bond lengths are 1.94 Å. The Fe(10)-F(7) bond length is 2.18 Å. Both Fe(10)-F(8) bond lengths are 2.27 Å. In the eleventh Fe site, Fe(11) is bonded to one O(8), two equivalent O(10), one F(11), and two equivalent F(10) atoms to form distorted FeO3F3 octahedra that share corners with two equivalent Fe(3)F6 octahedra, corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(9)O3F3 octahedra, corners with two equivalent Fe(7)O3F2 square pyramids, and edges with two equivalent Fe(11)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 49-51°. The Fe(11)-O(8) bond length is 1.88 Å. Both Fe(11)-O(10) bond lengths are 1.93 Å. The Fe(11)-F(11) bond length is 2.46 Å. Both Fe(11)-F(10) bond lengths are 2.21 Å. In the twelfth Fe site, Fe(12) is bonded to one O(7), two equivalent O(11), one F(12), and two equivalent F(9) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(3)F6 octahedra, corners with two equivalent Fe(9)O3F3 octahedra, corners with two equivalent Fe(8)O4F2 octahedra, corners with two equivalent Fe(1)O5F octahedra, and edges with two equivalent Fe(12)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. The Fe(12)-O(7) bond length is 1.91 Å. Both Fe(12)-O(11) bond lengths are 1.95 Å. The Fe(12)-F(12) bond length is 2.18 Å. Both Fe(12)-F(9) bond lengths are 2.12 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Fe(4), one Fe(5), and two equivalent Fe(2) atoms to form corner-sharing OFe4 trigonal pyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(6) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(4) atoms. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Fe(2), and two equivalent Fe(5) atoms. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Fe(8) and two equivalent Fe(6) atoms. In the sixth O site, O(6) is bonded in a trigonal non-coplanar geometry to one Fe(5) and two equivalent Fe(7) atoms. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Fe(12) and two equivalent Fe(8) atoms. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Fe(11) and two equivalent Fe(9) atoms. In the ninth O site, O(9) is bonded in a trigonal planar geometry to one Fe(8) and two equivalent Fe(10) atoms. In the tenth O site, O(10) is bonded in a trigonal planar geometry to one Fe(7) and two equivalent Fe(11) atoms. In the eleventh O site, O(11) is bonded in a trigonal planar geometry to one Fe(9) and two equivalent Fe(12) atoms. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Fe(10) and two equivalent Fe(1) atoms. There are twelve inequivalent F sites. In the first F site, F(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Fe(3) atoms. In the second F site, F(2) is bonded in a 3-coordinate geometry to one Fe(3) and two equivalent Fe(6) atoms. In the third F site, F(3) is bonded in a 4-coordinate geometry to two equivalent Fe(4) and two equivalent Fe(5) atoms. In the fourth F site, F(4) is bonded in a bent 150 degrees geometry to one Mg(1) and one Fe(9) atom. In the fifth F site, F(5) is bonded in a distorted T-shaped geometry to one Fe(4) and two equivalent Fe(8) atoms. In the sixth F site, F(6) is bonded in a 3-coordinate geometry to one Fe(6) and two equivalent Fe(9) atoms. In the seventh F site, F(7) is bonded in a distorted trigonal planar geometry to one Fe(10) and two equivalent Fe(7) atoms. In the eighth F site, F(8) is bonded in a 3-coordinate geometry to one Fe(2) and two equivalent Fe(10) atoms. In the ninth F site, F(9) is bonded in a distorted trigonal planar geometry to one Fe(1) and two equivalent Fe(12) atoms. In the tenth F site, F(10) is bonded in a distorted T-shaped geometry to one Fe(3) and two equivalent Fe(11) atoms. In the eleventh F site, F(11) is bonded in a 3-coordinate geometry to one Fe(11) and two equivalent Fe(2) atoms. In the twelfth F site, F(12) is bonded in a trigonal planar geometry to one Fe(12) and two equivalent Fe(3) atoms.