The compound described by MgFe8(OF)8 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(1), one O(8), and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share  a cornercorner with one Fe(3)O3F3 octahedra,  a cornercorner with one Fe(8)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 10-53°. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), two equivalent O(2), and two equivalent F(8) atoms to form distorted FeO3F2 square pyramids that share corners with two equivalent Fe(3)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, and edges with two equivalent Fe(1)O3F2 square pyramids. The corner-sharing octahedral tilt angles range from 48-56°. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one O(7), two equivalent O(1), and two equivalent O(8) atoms. In the third Fe site, Fe(3) is bonded to one O(1), two equivalent O(3), one F(3), and two equivalent F(1) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(6)F6 octahedra, corners with two equivalent Fe(1)O3F2 square pyramids,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with two equivalent Fe(3)O3F3 octahedra. The corner-sharing octahedral tilt angles are 47°. In the fourth Fe site, Fe(4) is bonded to one O(2), two equivalent O(4), one F(4), and two equivalent F(2) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(6)F6 octahedra, corners with two equivalent Fe(1)O3F2 square pyramids, corners with two equivalent Fe(5)O3F2 square pyramids, 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 are 46°. In the fifth Fe site, Fe(5) is bonded to one O(6), two equivalent O(5), and two equivalent F(4) atoms to form FeO3F2 square pyramids that share corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(8)O3F3 octahedra, and edges with two equivalent Fe(5)O3F2 square pyramids. The corner-sharing octahedral tilt angles range from 49-55°. In the sixth Fe site, Fe(6) is bonded to one F(2), one F(6), two equivalent F(3), and two equivalent F(5) atoms to form FeF6 octahedra that share corners with two equivalent Fe(3)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(8)O3F3 octahedra, and edges with two equivalent Fe(6)F6 octahedra. The corner-sharing octahedral tilt angles range from 46-47°. In the seventh Fe site, Fe(7) is bonded to one O(5), two equivalent O(7), one F(8), and two equivalent F(6) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(6)F6 octahedra, corners with two equivalent Fe(1)O3F2 square pyramids, corners with two equivalent Fe(5)O3F2 square pyramids, and edges with two equivalent Fe(7)O3F3 octahedra. The corner-sharing octahedral tilt angles are 47°. In the eighth Fe site, Fe(8) is bonded to one O(8), two equivalent O(6), one F(5), and two equivalent F(7) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(6)F6 octahedra, corners with two equivalent Fe(5)O3F2 square pyramids,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with two equivalent Fe(8)O3F3 octahedra. The corner-sharing octahedral tilt angles are 47°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(3), and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(4) 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(3) atoms. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Fe(4) atoms. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Fe(7) and two equivalent Fe(5) atoms. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Fe(5) and two equivalent Fe(8) atoms. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(7) atoms. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(8), and two equivalent Fe(2) atoms. There are eight inequivalent F sites. In the first F site, F(1) is bonded in an L-shaped geometry to two equivalent Fe(3) atoms. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Fe(6) and two equivalent Fe(4) atoms. In the third F site, F(3) is bonded in a distorted T-shaped geometry to one Fe(3) and two equivalent Fe(6) atoms. In the fourth F site, F(4) is bonded in a distorted trigonal planar geometry to one Fe(4) and two equivalent Fe(5) atoms. In the fifth F site, F(5) is bonded in a distorted T-shaped geometry to one Fe(8) and two equivalent Fe(6) atoms. In the sixth F site, F(6) is bonded in a distorted T-shaped geometry to one Fe(6) and two equivalent Fe(7) atoms. In the seventh F site, F(7) is bonded in a water-like geometry to two equivalent Fe(8) atoms. In the eighth F site, F(8) is bonded in a distorted T-shaped geometry to one Fe(7) and two equivalent Fe(1) atoms. is represented by the CIF file [CIF]
data_MgFe8(OF)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.081
_cell_length_b   10.137
_cell_length_c   3.053
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   83.257
_symmetry_Int_Tables_number   1
_cell_volume   309.835
_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  0.106  0.602  0.500  1.0
  Fe  Fe1  1  0.035  0.023  0.000  1.0
  Fe  Fe2  1  0.948  0.445  0.000  1.0
  Fe  Fe3  1  0.224  0.249  0.500  1.0
  Fe  Fe4  1  0.264  0.786  0.500  1.0
  Fe  Fe5  1  0.538  0.515  0.000  1.0
  Fe  Fe6  1  0.507  0.005  0.000  1.0
  Fe  Fe7  1  0.734  0.254  0.500  1.0
  Fe  Fe8  1  0.748  0.722  0.500  1.0
  O  O9  1  0.081  0.402  0.500  1.0
  O  O10  1  0.101  0.926  0.500  1.0
  O  O11  1  0.144  0.163  0.000  1.0
  O  O12  1  0.183  0.674  0.000  1.0
  O  O13  1  0.591  0.398  0.500  1.0
  O  O14  1  0.659  0.644  0.000  1.0
  O  O15  1  0.825  0.322  0.000  1.0
  O  O16  1  0.902  0.579  0.500  1.0
  F  F17  1  0.317  0.337  0.000  1.0
  F  F18  1  0.378  0.868  0.000  1.0
  F  F19  1  0.399  0.114  0.500  1.0
  F  F20  1  0.424  0.606  0.500  1.0
  F  F21  1  0.617  0.898  0.500  1.0
  F  F22  1  0.648  0.148  0.000  1.0
  F  F23  1  0.836  0.813  0.000  1.0
  F  F24  1  0.889  0.095  0.500  1.0
[/CIF]
.
The compound described by MgFe8(OF)8 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(1), one O(8), and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share  a cornercorner with one Fe(3)O3F3 octahedra,  a cornercorner with one Fe(8)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 10-53°. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), two equivalent O(2), and two equivalent F(8) atoms to form distorted FeO3F2 square pyramids that share corners with two equivalent Fe(3)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, and edges with two equivalent Fe(1)O3F2 square pyramids. The corner-sharing octahedral tilt angles range from 48-56°. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one O(7), two equivalent O(1), and two equivalent O(8) atoms. In the third Fe site, Fe(3) is bonded to one O(1), two equivalent O(3), one F(3), and two equivalent F(1) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(6)F6 octahedra, corners with two equivalent Fe(1)O3F2 square pyramids,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with two equivalent Fe(3)O3F3 octahedra. The corner-sharing octahedral tilt angles are 47°. In the fourth Fe site, Fe(4) is bonded to one O(2), two equivalent O(4), one F(4), and two equivalent F(2) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(6)F6 octahedra, corners with two equivalent Fe(1)O3F2 square pyramids, corners with two equivalent Fe(5)O3F2 square pyramids, 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 are 46°. In the fifth Fe site, Fe(5) is bonded to one O(6), two equivalent O(5), and two equivalent F(4) atoms to form FeO3F2 square pyramids that share corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(8)O3F3 octahedra, and edges with two equivalent Fe(5)O3F2 square pyramids. The corner-sharing octahedral tilt angles range from 49-55°. In the sixth Fe site, Fe(6) is bonded to one F(2), one F(6), two equivalent F(3), and two equivalent F(5) atoms to form FeF6 octahedra that share corners with two equivalent Fe(3)O3F3 octahedra, corners with two equivalent Fe(4)O3F3 octahedra, corners with two equivalent Fe(7)O3F3 octahedra, corners with two equivalent Fe(8)O3F3 octahedra, and edges with two equivalent Fe(6)F6 octahedra. The corner-sharing octahedral tilt angles range from 46-47°. In the seventh Fe site, Fe(7) is bonded to one O(5), two equivalent O(7), one F(8), and two equivalent F(6) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(6)F6 octahedra, corners with two equivalent Fe(1)O3F2 square pyramids, corners with two equivalent Fe(5)O3F2 square pyramids, and edges with two equivalent Fe(7)O3F3 octahedra. The corner-sharing octahedral tilt angles are 47°. In the eighth Fe site, Fe(8) is bonded to one O(8), two equivalent O(6), one F(5), and two equivalent F(7) atoms to form FeO3F3 octahedra that share corners with two equivalent Fe(6)F6 octahedra, corners with two equivalent Fe(5)O3F2 square pyramids,  a cornercorner with one Mg(1)O4 tetrahedra, and edges with two equivalent Fe(8)O3F3 octahedra. The corner-sharing octahedral tilt angles are 47°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(3), and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(4) 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(3) atoms. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Fe(4) atoms. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Fe(7) and two equivalent Fe(5) atoms. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Fe(5) and two equivalent Fe(8) atoms. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(7) atoms. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(8), and two equivalent Fe(2) atoms. There are eight inequivalent F sites. In the first F site, F(1) is bonded in an L-shaped geometry to two equivalent Fe(3) atoms. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Fe(6) and two equivalent Fe(4) atoms. In the third F site, F(3) is bonded in a distorted T-shaped geometry to one Fe(3) and two equivalent Fe(6) atoms. In the fourth F site, F(4) is bonded in a distorted trigonal planar geometry to one Fe(4) and two equivalent Fe(5) atoms. In the fifth F site, F(5) is bonded in a distorted T-shaped geometry to one Fe(8) and two equivalent Fe(6) atoms. In the sixth F site, F(6) is bonded in a distorted T-shaped geometry to one Fe(6) and two equivalent Fe(7) atoms. In the seventh F site, F(7) is bonded in a water-like geometry to two equivalent Fe(8) atoms. In the eighth F site, F(8) is bonded in a distorted T-shaped geometry to one Fe(7) and two equivalent Fe(1) atoms. is represented by the CIF file [CIF]
data_MgFe8(OF)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.081
_cell_length_b   10.137
_cell_length_c   3.053
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   83.257
_symmetry_Int_Tables_number   1
_cell_volume   309.835
_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  0.106  0.602  0.500  1.0
  Fe  Fe1  1  0.035  0.023  0.000  1.0
  Fe  Fe2  1  0.948  0.445  0.000  1.0
  Fe  Fe3  1  0.224  0.249  0.500  1.0
  Fe  Fe4  1  0.264  0.786  0.500  1.0
  Fe  Fe5  1  0.538  0.515  0.000  1.0
  Fe  Fe6  1  0.507  0.005  0.000  1.0
  Fe  Fe7  1  0.734  0.254  0.500  1.0
  Fe  Fe8  1  0.748  0.722  0.500  1.0
  O  O9  1  0.081  0.402  0.500  1.0
  O  O10  1  0.101  0.926  0.500  1.0
  O  O11  1  0.144  0.163  0.000  1.0
  O  O12  1  0.183  0.674  0.000  1.0
  O  O13  1  0.591  0.398  0.500  1.0
  O  O14  1  0.659  0.644  0.000  1.0
  O  O15  1  0.825  0.322  0.000  1.0
  O  O16  1  0.902  0.579  0.500  1.0
  F  F17  1  0.317  0.337  0.000  1.0
  F  F18  1  0.378  0.868  0.000  1.0
  F  F19  1  0.399  0.114  0.500  1.0
  F  F20  1  0.424  0.606  0.500  1.0
  F  F21  1  0.617  0.898  0.500  1.0
  F  F22  1  0.648  0.148  0.000  1.0
  F  F23  1  0.836  0.813  0.000  1.0
  F  F24  1  0.889  0.095  0.500  1.0
[/CIF]
.