The crystal structure described by MgFe8(OF)8 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one F(5), one F(8), two equivalent F(6), and two equivalent F(7) atoms to form MgF6 octahedra that share  a cornercorner with one Fe(7)O3F tetrahedra,  a cornercorner with one Fe(8)O3F trigonal pyramid, edges with two equivalent Mg(1)F6 octahedra, and edges with two equivalent Fe(6)F6 octahedra. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(2), one F(7), and two equivalent F(8) atoms. In the second Fe site, Fe(2) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(8) atoms to form FeO6 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)O3F tetrahedra, corners with two equivalent Fe(8)O3F trigonal pyramids, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-57°. 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(5)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-51°. 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(5)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(4)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-57°. In the fifth Fe site, Fe(5) is bonded to one O(6), two equivalent O(5), one F(1), and two equivalent F(4) atoms to form FeO3F3 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)O3F tetrahedra, corners with two equivalent Fe(8)O3F trigonal pyramids, and edges with two equivalent Fe(5)O3F3 octahedra. The corner-sharing octahedral tilt angles are 48°. 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 distorted 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(8)O3F trigonal pyramids, edges with two equivalent Mg(1)F6 octahedra, and edges with two equivalent Fe(6)F6 octahedra. The corner-sharing octahedral tilt angles range from 47-50°. In the seventh Fe site, Fe(7) is bonded to one O(5), two equivalent O(7), and one F(8) atom to form FeO3F tetrahedra that share  a cornercorner with one Mg(1)F6 octahedra, corners with two equivalent Fe(5)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Fe(7)O3F tetrahedra. The corner-sharing octahedral tilt angles range from 60-62°. In the eighth Fe site, Fe(8) is bonded to one O(8), two equivalent O(6), and one F(5) atom to form distorted FeO3F trigonal pyramids that share  a cornercorner with one Mg(1)F6 octahedra, corners with two equivalent Fe(6)F6 octahedra, corners with two equivalent Fe(5)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Fe(8)O3F trigonal pyramids. The corner-sharing octahedral tilt angles range from 55-72°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to 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 trigonal planar geometry to one Fe(2) and two equivalent Fe(4) atoms. In the fifth O site, O(5) is bonded in a trigonal non-coplanar 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 trigonal planar geometry to 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 a distorted T-shaped 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(6) and two equivalent Fe(4) atoms. In the third F site, F(3) is bonded in a trigonal planar 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 to one Mg(1), one Fe(8), and two equivalent Fe(6) atoms to form distorted corner-sharing FMgFe3 tetrahedra. In the sixth F site, F(6) is bonded in a trigonal non-coplanar geometry to two equivalent Mg(1) and one Fe(6) atom. In the seventh F site, F(7) is bonded in a trigonal non-coplanar geometry to two equivalent Mg(1) and one Fe(1) atom. In the eighth F site, F(8) is bonded in a distorted bent 120 degrees geometry to one Mg(1), one Fe(7), and two equivalent Fe(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgFe8(OF)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.757
_cell_length_b   9.914
_cell_length_c   3.183
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   82.927
_symmetry_Int_Tables_number   1
_cell_volume   305.589
_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  0.753  0.001  0.500  1.0
  Fe  Fe1  1  0.061  0.015  0.000  1.0
  Fe  Fe2  1  0.016  0.529  0.000  1.0
  Fe  Fe3  1  0.226  0.260  0.500  1.0
  Fe  Fe4  1  0.226  0.731  0.500  1.0
  Fe  Fe5  1  0.507  0.466  0.000  1.0
  Fe  Fe6  1  0.469  0.971  0.000  1.0
  Fe  Fe7  1  0.797  0.340  0.500  1.0
  Fe  Fe8  1  0.714  0.650  0.500  1.0
  O  O9  1  0.115  0.424  0.500  1.0
  O  O10  1  0.122  0.920  0.500  1.0
  O  O11  1  0.150  0.170  0.000  1.0
  O  O12  1  0.149  0.666  0.000  1.0
  O  O13  1  0.601  0.369  0.500  1.0
  O  O14  1  0.611  0.613  0.000  1.0
  O  O15  1  0.876  0.387  0.000  1.0
  O  O16  1  0.910  0.617  0.500  1.0
  F  F17  1  0.356  0.328  0.000  1.0
  F  F18  1  0.350  0.819  0.000  1.0
  F  F19  1  0.384  0.087  0.500  1.0
  F  F20  1  0.383  0.566  0.500  1.0
  F  F21  1  0.604  0.879  0.500  1.0
  F  F22  1  0.641  0.082  0.000  1.0
  F  F23  1  0.872  0.932  0.000  1.0
  F  F24  1  0.880  0.142  0.500  1.0
[/CIF]
.
The crystal structure described by MgFe8(OF)8 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one F(5), one F(8), two equivalent F(6), and two equivalent F(7) atoms to form MgF6 octahedra that share  a cornercorner with one Fe(7)O3F tetrahedra,  a cornercorner with one Fe(8)O3F trigonal pyramid, edges with two equivalent Mg(1)F6 octahedra, and edges with two equivalent Fe(6)F6 octahedra. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(2), one F(7), and two equivalent F(8) atoms. In the second Fe site, Fe(2) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(8) atoms to form FeO6 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)O3F tetrahedra, corners with two equivalent Fe(8)O3F trigonal pyramids, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-57°. 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(5)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-51°. 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(5)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(4)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-57°. In the fifth Fe site, Fe(5) is bonded to one O(6), two equivalent O(5), one F(1), and two equivalent F(4) atoms to form FeO3F3 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)O3F tetrahedra, corners with two equivalent Fe(8)O3F trigonal pyramids, and edges with two equivalent Fe(5)O3F3 octahedra. The corner-sharing octahedral tilt angles are 48°. 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 distorted 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(8)O3F trigonal pyramids, edges with two equivalent Mg(1)F6 octahedra, and edges with two equivalent Fe(6)F6 octahedra. The corner-sharing octahedral tilt angles range from 47-50°. In the seventh Fe site, Fe(7) is bonded to one O(5), two equivalent O(7), and one F(8) atom to form FeO3F tetrahedra that share  a cornercorner with one Mg(1)F6 octahedra, corners with two equivalent Fe(5)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Fe(7)O3F tetrahedra. The corner-sharing octahedral tilt angles range from 60-62°. In the eighth Fe site, Fe(8) is bonded to one O(8), two equivalent O(6), and one F(5) atom to form distorted FeO3F trigonal pyramids that share  a cornercorner with one Mg(1)F6 octahedra, corners with two equivalent Fe(6)F6 octahedra, corners with two equivalent Fe(5)O3F3 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Fe(8)O3F trigonal pyramids. The corner-sharing octahedral tilt angles range from 55-72°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to 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 trigonal planar geometry to one Fe(2) and two equivalent Fe(4) atoms. In the fifth O site, O(5) is bonded in a trigonal non-coplanar 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 trigonal planar geometry to 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 a distorted T-shaped 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(6) and two equivalent Fe(4) atoms. In the third F site, F(3) is bonded in a trigonal planar 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 to one Mg(1), one Fe(8), and two equivalent Fe(6) atoms to form distorted corner-sharing FMgFe3 tetrahedra. In the sixth F site, F(6) is bonded in a trigonal non-coplanar geometry to two equivalent Mg(1) and one Fe(6) atom. In the seventh F site, F(7) is bonded in a trigonal non-coplanar geometry to two equivalent Mg(1) and one Fe(1) atom. In the eighth F site, F(8) is bonded in a distorted bent 120 degrees geometry to one Mg(1), one Fe(7), and two equivalent Fe(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgFe8(OF)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.757
_cell_length_b   9.914
_cell_length_c   3.183
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   82.927
_symmetry_Int_Tables_number   1
_cell_volume   305.589
_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  0.753  0.001  0.500  1.0
  Fe  Fe1  1  0.061  0.015  0.000  1.0
  Fe  Fe2  1  0.016  0.529  0.000  1.0
  Fe  Fe3  1  0.226  0.260  0.500  1.0
  Fe  Fe4  1  0.226  0.731  0.500  1.0
  Fe  Fe5  1  0.507  0.466  0.000  1.0
  Fe  Fe6  1  0.469  0.971  0.000  1.0
  Fe  Fe7  1  0.797  0.340  0.500  1.0
  Fe  Fe8  1  0.714  0.650  0.500  1.0
  O  O9  1  0.115  0.424  0.500  1.0
  O  O10  1  0.122  0.920  0.500  1.0
  O  O11  1  0.150  0.170  0.000  1.0
  O  O12  1  0.149  0.666  0.000  1.0
  O  O13  1  0.601  0.369  0.500  1.0
  O  O14  1  0.611  0.613  0.000  1.0
  O  O15  1  0.876  0.387  0.000  1.0
  O  O16  1  0.910  0.617  0.500  1.0
  F  F17  1  0.356  0.328  0.000  1.0
  F  F18  1  0.350  0.819  0.000  1.0
  F  F19  1  0.384  0.087  0.500  1.0
  F  F20  1  0.383  0.566  0.500  1.0
  F  F21  1  0.604  0.879  0.500  1.0
  F  F22  1  0.641  0.082  0.000  1.0
  F  F23  1  0.872  0.932  0.000  1.0
  F  F24  1  0.880  0.142  0.500  1.0
[/CIF]
.