The crystal structure described by MgFe12(OF)12 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(12), one O(2), and two equivalent O(3) atoms to form distorted MgO4 tetrahedra that share  a cornercorner with one Fe(10)O3F3 octahedra,  a cornercorner with one Fe(6)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, and  an edgeedge with one Fe(4)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 3-62°. There are twelve inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to two equivalent O(12), two equivalent O(2), and one F(9) atom. 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 42-54°. 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 45-48°. 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(7)O3F3 octahedra, corners with two equivalent Fe(8)O4F2 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, edges with two equivalent Fe(4)O3F3 octahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-52°. 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 47-54°. 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(8)O4F2 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with two equivalent Fe(6)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-52°. 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), 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, corners with two equivalent Fe(6)O3F3 octahedra, and edges with two equivalent Fe(8)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 46-55°. 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 47-54°. 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(7)O3F3 octahedra, corners with two equivalent Fe(8)O4F2 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with two equivalent Fe(10)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-54°. 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 48-55°. 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 distorted 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, and edges with two equivalent Fe(12)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. 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 in a distorted rectangular see-saw-like geometry to one Mg(1), one Fe(6), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Fe(4) atoms. 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 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 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 distorted rectangular see-saw-like geometry to one Mg(1), 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 T-shaped 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 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 distorted trigonal planar 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 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 trigonal planar 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. is represented by the CIF file [CIF]
data_MgFe12(OF)12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.599
_cell_length_b   14.681
_cell_length_c   3.099
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   87.102
_symmetry_Int_Tables_number   1
_cell_volume   436.164
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Mg  Mg0  1  0.107  0.064  0.500  1.0
  Fe  Fe1  1  0.941  0.968  0.000  1.0
  Fe  Fe2  1  0.020  0.333  0.000  1.0
  Fe  Fe3  1  0.004  0.671  0.000  1.0
  Fe  Fe4  1  0.278  0.194  0.500  1.0
  Fe  Fe5  1  0.243  0.484  0.500  1.0
  Fe  Fe6  1  0.255  0.855  0.500  1.0
  Fe  Fe7  1  0.520  0.358  0.000  1.0
  Fe  Fe8  1  0.515  0.995  0.000  1.0
  Fe  Fe9  1  0.496  0.656  0.000  1.0
  Fe  Fe10  1  0.746  0.150  0.500  1.0
  Fe  Fe11  1  0.736  0.503  0.500  1.0
  Fe  Fe12  1  0.695  0.814  0.500  1.0
  O  O13  1  0.116  0.277  0.500  1.0
  O  O14  1  0.088  0.932  0.500  1.0
  O  O15  1  0.193  0.126  0.000  1.0
  O  O16  1  0.148  0.436  0.000  1.0
  O  O17  1  0.350  0.908  0.000  1.0
  O  O18  1  0.413  0.403  0.500  1.0
  O  O19  1  0.602  0.935  0.500  1.0
  O  O20  1  0.585  0.596  0.500  1.0
  O  O21  1  0.648  0.104  0.000  1.0
  O  O22  1  0.672  0.437  0.000  1.0
  O  O23  1  0.615  0.759  0.000  1.0
  O  O24  1  0.902  0.064  0.500  1.0
  F  F25  1  0.108  0.601  0.500  1.0
  F  F26  1  0.156  0.775  0.000  1.0
  F  F27  1  0.387  0.245  0.000  1.0
  F  F28  1  0.336  0.563  0.000  1.0
  F  F29  1  0.412  0.076  0.500  1.0
  F  F30  1  0.380  0.723  0.500  1.0
  F  F31  1  0.615  0.277  0.500  1.0
  F  F32  1  0.861  0.235  0.000  1.0
  F  F33  1  0.819  0.862  0.000  1.0
  F  F34  1  0.850  0.563  0.000  1.0
  F  F35  1  0.909  0.399  0.500  1.0
  F  F36  1  0.879  0.724  0.500  1.0
[/CIF]
.
The crystal structure described by MgFe12(OF)12 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(12), one O(2), and two equivalent O(3) atoms to form distorted MgO4 tetrahedra that share  a cornercorner with one Fe(10)O3F3 octahedra,  a cornercorner with one Fe(6)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, and  an edgeedge with one Fe(4)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 3-62°. There are twelve inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to two equivalent O(12), two equivalent O(2), and one F(9) atom. 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 42-54°. 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 45-48°. 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(7)O3F3 octahedra, corners with two equivalent Fe(8)O4F2 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, edges with two equivalent Fe(4)O3F3 octahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-52°. 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 47-54°. 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(8)O4F2 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with two equivalent Fe(6)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 45-52°. 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), 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, corners with two equivalent Fe(6)O3F3 octahedra, and edges with two equivalent Fe(8)O4F2 octahedra. The corner-sharing octahedral tilt angles range from 46-55°. 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 47-54°. 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(7)O3F3 octahedra, corners with two equivalent Fe(8)O4F2 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with two equivalent Fe(10)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 42-54°. 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 48-55°. 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 distorted 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, and edges with two equivalent Fe(12)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. 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 in a distorted rectangular see-saw-like geometry to one Mg(1), one Fe(6), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Fe(4) atoms. 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 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 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 distorted rectangular see-saw-like geometry to one Mg(1), 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 T-shaped 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 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 distorted trigonal planar 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 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 trigonal planar 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. is represented by the CIF file [CIF]
data_MgFe12(OF)12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.599
_cell_length_b   14.681
_cell_length_c   3.099
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   87.102
_symmetry_Int_Tables_number   1
_cell_volume   436.164
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Mg  Mg0  1  0.107  0.064  0.500  1.0
  Fe  Fe1  1  0.941  0.968  0.000  1.0
  Fe  Fe2  1  0.020  0.333  0.000  1.0
  Fe  Fe3  1  0.004  0.671  0.000  1.0
  Fe  Fe4  1  0.278  0.194  0.500  1.0
  Fe  Fe5  1  0.243  0.484  0.500  1.0
  Fe  Fe6  1  0.255  0.855  0.500  1.0
  Fe  Fe7  1  0.520  0.358  0.000  1.0
  Fe  Fe8  1  0.515  0.995  0.000  1.0
  Fe  Fe9  1  0.496  0.656  0.000  1.0
  Fe  Fe10  1  0.746  0.150  0.500  1.0
  Fe  Fe11  1  0.736  0.503  0.500  1.0
  Fe  Fe12  1  0.695  0.814  0.500  1.0
  O  O13  1  0.116  0.277  0.500  1.0
  O  O14  1  0.088  0.932  0.500  1.0
  O  O15  1  0.193  0.126  0.000  1.0
  O  O16  1  0.148  0.436  0.000  1.0
  O  O17  1  0.350  0.908  0.000  1.0
  O  O18  1  0.413  0.403  0.500  1.0
  O  O19  1  0.602  0.935  0.500  1.0
  O  O20  1  0.585  0.596  0.500  1.0
  O  O21  1  0.648  0.104  0.000  1.0
  O  O22  1  0.672  0.437  0.000  1.0
  O  O23  1  0.615  0.759  0.000  1.0
  O  O24  1  0.902  0.064  0.500  1.0
  F  F25  1  0.108  0.601  0.500  1.0
  F  F26  1  0.156  0.775  0.000  1.0
  F  F27  1  0.387  0.245  0.000  1.0
  F  F28  1  0.336  0.563  0.000  1.0
  F  F29  1  0.412  0.076  0.500  1.0
  F  F30  1  0.380  0.723  0.500  1.0
  F  F31  1  0.615  0.277  0.500  1.0
  F  F32  1  0.861  0.235  0.000  1.0
  F  F33  1  0.819  0.862  0.000  1.0
  F  F34  1  0.850  0.563  0.000  1.0
  F  F35  1  0.909  0.399  0.500  1.0
  F  F36  1  0.879  0.724  0.500  1.0
[/CIF]
.