MgFe12(OF)12 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(3), one O(5), two equivalent O(2), and two equivalent F(5) atoms to form MgO4F2 octahedra that share corners with two equivalent Fe(1)O5F octahedra,  a cornercorner with one Fe(8)O4 tetrahedra, edges with two equivalent Mg(1)O4F2 octahedra, edges with two equivalent Fe(4)O3F3 octahedra, edges with two equivalent Fe(6)O3F3 octahedra, and  a faceface with one Fe(1)O5F octahedra. The corner-sharing octahedral tilt angles are 45°. 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 distorted FeO5F octahedra that share corners with two equivalent Mg(1)O4F2 octahedra, corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(6)O3F3 octahedra, edges with two equivalent Fe(1)O5F octahedra, and  a faceface with one Mg(1)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 45-53°. 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 a mixture of edge and corner-sharing FeO3F3 octahedra. The corner-sharing octahedral tilt angles range from 46-54°. 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 FeF6 octahedra that share corners with two equivalent Fe(11)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Fe(5)O3F3 octahedra, corners with two equivalent Fe(6)O3F3 octahedra, and edges with two equivalent Fe(3)F6 octahedra. The corner-sharing octahedral tilt angles range from 47-49°. 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 FeO3F3 octahedra that share corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(1)O5F octahedra, edges with two equivalent Mg(1)O4F2 octahedra, and edges with two equivalent Fe(4)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. In the fifth Fe site, Fe(5) is bonded to one O(6), two equivalent O(4), one F(1), and two equivalent F(4) atoms to form 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(7)O3F3 octahedra, corners with two equivalent Fe(9)O3F3 octahedra, and edges with two equivalent Fe(5)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. In the sixth Fe site, Fe(6) is bonded to one O(2), two equivalent O(5), one F(6), and two equivalent F(2) 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(1)O5F octahedra, corners with two equivalent Fe(8)O4 tetrahedra, edges with two equivalent Mg(1)O4F2 octahedra, and edges with two equivalent Fe(6)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-48°. In the seventh Fe site, Fe(7) is bonded to one O(10), two equivalent O(6), one F(3), and two equivalent F(7) atoms to form a mixture of edge and corner-sharing FeO3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-55°. In the eighth Fe site, Fe(8) is bonded to one O(5), one O(9), and two equivalent O(7) atoms to form distorted FeO4 tetrahedra that share  a cornercorner with one Mg(1)O4F2 octahedra, corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Fe(6)O3F3 octahedra, and corners with two equivalent Fe(8)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-94°. 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 a mixture of edge and corner-sharing FeO3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-53°. 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 FeO3F3 octahedra that share corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(1)O5F octahedra, corners with two equivalent Fe(8)O4 tetrahedra, and edges with two equivalent Fe(10)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 46-53°. 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 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(7)O3F3 octahedra, corners with two equivalent Fe(9)O3F3 octahedra, and edges with two equivalent Fe(11)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-55°. 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(1)O5F octahedra, corners with two equivalent Fe(8)O4 tetrahedra, and edges with two equivalent Fe(12)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(4) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded to two equivalent Mg(1), one Fe(6), and two equivalent Fe(1) atoms to form distorted OMg2Fe3 trigonal bipyramids that share edges with two equivalent O(2)Mg2Fe3 trigonal bipyramids, edges with two equivalent O(3)MgFe3 trigonal pyramids, and edges with two equivalent O(5)MgFe3 trigonal pyramids. In the third O site, O(3) is bonded to one Mg(1), one Fe(1), and two equivalent Fe(4) atoms to form distorted OMgFe3 trigonal pyramids that share  a cornercorner with one O(5)MgFe3 trigonal pyramid, corners with two equivalent O(3)MgFe3 trigonal pyramids, and edges with two equivalent O(2)Mg2Fe3 trigonal bipyramids. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(5) atoms. In the fifth O site, O(5) is bonded to one Mg(1), one Fe(8), and two equivalent Fe(6) atoms to form OMgFe3 trigonal pyramids that share  a cornercorner with one O(3)MgFe3 trigonal pyramid, corners with two equivalent O(5)MgFe3 trigonal pyramids, and edges with two equivalent O(2)Mg2Fe3 trigonal bipyramids. In the sixth O site, O(6) is bonded in a trigonal planar 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 trigonal planar geometry to one Fe(5) and two equivalent Fe(3) atoms. In the second F site, F(2) is bonded in a distorted trigonal planar geometry to one Fe(3) and two equivalent Fe(6) atoms. In the third F site, F(3) is bonded in a distorted trigonal planar geometry to one Fe(7) and two equivalent Fe(4) atoms. In the fourth F site, F(4) is bonded in a distorted T-shaped geometry to one Fe(9) and two equivalent Fe(5) atoms. In the fifth F site, F(5) is bonded in a 3-coordinate geometry to two equivalent Mg(1) and one Fe(4) atom. In the sixth F site, F(6) is bonded in a distorted T-shaped geometry to one Fe(6) and two equivalent Fe(9) atoms. In the seventh F site, F(7) is bonded in a distorted T-shaped geometry to one Fe(10) and two equivalent Fe(7) atoms. In the eighth F site, F(8) is bonded in a distorted T-shaped geometry to one Fe(2) and two equivalent Fe(10) atoms. In the ninth F site, F(9) is bonded in a distorted T-shaped 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 distorted trigonal planar geometry to one Fe(11) and two equivalent Fe(2) atoms. In the twelfth F site, F(12) is bonded in a distorted 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(3), one O(5), two equivalent O(2), and two equivalent F(5) atoms to form MgO4F2 octahedra that share corners with two equivalent Fe(1)O5F octahedra,  a cornercorner with one Fe(8)O4 tetrahedra, edges with two equivalent Mg(1)O4F2 octahedra, edges with two equivalent Fe(4)O3F3 octahedra, edges with two equivalent Fe(6)O3F3 octahedra, and  a faceface with one Fe(1)O5F octahedra. The corner-sharing octahedral tilt angles are 45°. The Mg(1)-O(3) bond length is 1.98 Å. The Mg(1)-O(5) bond length is 1.96 Å. Both Mg(1)-O(2) bond lengths are 2.17 Å. Both Mg(1)-F(5) bond lengths are 2.02 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 distorted FeO5F octahedra that share corners with two equivalent Mg(1)O4F2 octahedra, corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(6)O3F3 octahedra, edges with two equivalent Fe(1)O5F octahedra, and  a faceface with one Mg(1)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 45-53°. The Fe(1)-O(3) bond length is 2.14 Å. Both Fe(1)-O(12) bond lengths are 1.95 Å. Both Fe(1)-O(2) bond lengths are 2.28 Å. The Fe(1)-F(9) bond length is 2.04 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 a mixture of edge and corner-sharing FeO3F3 octahedra. The corner-sharing octahedral tilt angles range from 46-54°. The Fe(2)-O(4) bond length is 1.95 Å. Both Fe(2)-O(1) bond lengths are 1.95 Å. The Fe(2)-F(8) bond length is 2.15 Å. Both Fe(2)-F(11) bond lengths are 2.10 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 FeF6 octahedra that share corners with two equivalent Fe(11)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Fe(5)O3F3 octahedra, corners with two equivalent Fe(6)O3F3 octahedra, and edges with two equivalent Fe(3)F6 octahedra. The corner-sharing octahedral tilt angles range from 47-49°. The Fe(3)-F(10) bond length is 2.14 Å. The Fe(3)-F(2) bond length is 2.17 Å. Both Fe(3)-F(1) bond lengths are 2.07 Å. Both Fe(3)-F(12) bond lengths are 2.07 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 FeO3F3 octahedra that share corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(1)O5F octahedra, edges with two equivalent Mg(1)O4F2 octahedra, and edges with two equivalent Fe(4)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. The Fe(4)-O(1) bond length is 1.89 Å. Both Fe(4)-O(3) bond lengths are 1.97 Å. The Fe(4)-F(5) bond length is 2.26 Å. Both Fe(4)-F(3) bond lengths are 2.11 Å. In the fifth Fe site, Fe(5) is bonded to one O(6), two equivalent O(4), one F(1), and two equivalent F(4) atoms to form 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(7)O3F3 octahedra, corners with two equivalent Fe(9)O3F3 octahedra, and edges with two equivalent Fe(5)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. The Fe(5)-O(6) bond length is 1.95 Å. Both Fe(5)-O(4) bond lengths are 1.95 Å. The Fe(5)-F(1) bond length is 2.13 Å. Both Fe(5)-F(4) bond lengths are 2.13 Å. In the sixth Fe site, Fe(6) is bonded to one O(2), two equivalent O(5), one F(6), and two equivalent F(2) 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(1)O5F octahedra, corners with two equivalent Fe(8)O4 tetrahedra, edges with two equivalent Mg(1)O4F2 octahedra, and edges with two equivalent Fe(6)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-48°. The Fe(6)-O(2) bond length is 2.08 Å. Both Fe(6)-O(5) bond lengths are 1.97 Å. The Fe(6)-F(6) bond length is 2.16 Å. Both Fe(6)-F(2) bond lengths are 2.09 Å. In the seventh Fe site, Fe(7) is bonded to one O(10), two equivalent O(6), one F(3), and two equivalent F(7) atoms to form a mixture of edge and corner-sharing FeO3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-55°. The Fe(7)-O(10) bond length is 1.93 Å. Both Fe(7)-O(6) bond lengths are 1.96 Å. The Fe(7)-F(3) bond length is 2.16 Å. Both Fe(7)-F(7) bond lengths are 2.11 Å. In the eighth Fe site, Fe(8) is bonded to one O(5), one O(9), and two equivalent O(7) atoms to form distorted FeO4 tetrahedra that share  a cornercorner with one Mg(1)O4F2 octahedra, corners with two equivalent Fe(10)O3F3 octahedra, corners with two equivalent Fe(12)O3F3 octahedra, corners with two equivalent Fe(6)O3F3 octahedra, and corners with two equivalent Fe(8)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-94°. The Fe(8)-O(5) bond length is 2.25 Å. The Fe(8)-O(9) bond length is 2.01 Å. Both Fe(8)-O(7) bond lengths are 1.93 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 a mixture of edge and corner-sharing FeO3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-53°. The Fe(9)-O(11) bond length is 1.92 Å. Both Fe(9)-O(8) bond lengths are 1.95 Å. The Fe(9)-F(4) bond length is 2.19 Å. Both Fe(9)-F(6) bond lengths are 2.17 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 FeO3F3 octahedra that share corners with two equivalent Fe(2)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(1)O5F octahedra, corners with two equivalent Fe(8)O4 tetrahedra, and edges with two equivalent Fe(10)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 46-53°. The Fe(10)-O(12) bond length is 2.00 Å. Both Fe(10)-O(9) bond lengths are 1.92 Å. The Fe(10)-F(7) bond length is 2.30 Å. Both Fe(10)-F(8) bond lengths are 2.18 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 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(7)O3F3 octahedra, corners with two equivalent Fe(9)O3F3 octahedra, and edges with two equivalent Fe(11)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-55°. The Fe(11)-O(8) bond length is 1.94 Å. Both Fe(11)-O(10) bond lengths are 1.94 Å. The Fe(11)-F(11) bond length is 2.17 Å. Both Fe(11)-F(10) bond lengths are 2.14 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(1)O5F octahedra, corners with two equivalent Fe(8)O4 tetrahedra, and edges with two equivalent Fe(12)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. The Fe(12)-O(7) bond length is 1.84 Å. Both Fe(12)-O(11) bond lengths are 1.95 Å. The Fe(12)-F(12) bond length is 2.12 Å. Both Fe(12)-F(9) bond lengths are 2.22 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(4) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded to two equivalent Mg(1), one Fe(6), and two equivalent Fe(1) atoms to form distorted OMg2Fe3 trigonal bipyramids that share edges with two equivalent O(2)Mg2Fe3 trigonal bipyramids, edges with two equivalent O(3)MgFe3 trigonal pyramids, and edges with two equivalent O(5)MgFe3 trigonal pyramids. In the third O site, O(3) is bonded to one Mg(1), one Fe(1), and two equivalent Fe(4) atoms to form distorted OMgFe3 trigonal pyramids that share  a cornercorner with one O(5)MgFe3 trigonal pyramid, corners with two equivalent O(3)MgFe3 trigonal pyramids, and edges with two equivalent O(2)Mg2Fe3 trigonal bipyramids. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(5) atoms. In the fifth O site, O(5) is bonded to one Mg(1), one Fe(8), and two equivalent Fe(6) atoms to form OMgFe3 trigonal pyramids that share  a cornercorner with one O(3)MgFe3 trigonal pyramid, corners with two equivalent O(5)MgFe3 trigonal pyramids, and edges with two equivalent O(2)Mg2Fe3 trigonal bipyramids. In the sixth O site, O(6) is bonded in a trigonal planar 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 trigonal planar geometry to one Fe(5) and two equivalent Fe(3) atoms. In the second F site, F(2) is bonded in a distorted trigonal planar geometry to one Fe(3) and two equivalent Fe(6) atoms. In the third F site, F(3) is bonded in a distorted trigonal planar geometry to one Fe(7) and two equivalent Fe(4) atoms. In the fourth F site, F(4) is bonded in a distorted T-shaped geometry to one Fe(9) and two equivalent Fe(5) atoms. In the fifth F site, F(5) is bonded in a 3-coordinate geometry to two equivalent Mg(1) and one Fe(4) atom. In the sixth F site, F(6) is bonded in a distorted T-shaped geometry to one Fe(6) and two equivalent Fe(9) atoms. In the seventh F site, F(7) is bonded in a distorted T-shaped geometry to one Fe(10) and two equivalent Fe(7) atoms. In the eighth F site, F(8) is bonded in a distorted T-shaped geometry to one Fe(2) and two equivalent Fe(10) atoms. In the ninth F site, F(9) is bonded in a distorted T-shaped 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 distorted trigonal planar geometry to one Fe(11) and two equivalent Fe(2) atoms. In the twelfth F site, F(12) is bonded in a distorted trigonal planar geometry to one Fe(12) and two equivalent Fe(3) atoms.