The crystal structure described by MgFe8(OF)8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(4), two equivalent O(2), two equivalent O(8), and one F(7) atom to form MgO5F octahedra that share edges with two equivalent Mg(1)O5F octahedra, edges with two equivalent Fe(4)O3F3 octahedra, and edges with two equivalent Fe(8)O3F3 octahedra. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(2), and two equivalent F(8) atoms. In the second Fe site, Fe(2) is bonded in a 6-coordinate geometry to one O(4), 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(5)O3F3 octahedra, and edges with two equivalent Fe(3)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-50°. 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, edges with two equivalent Mg(1)O5F octahedra, and edges with two equivalent Fe(4)O3F3 octahedra. 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), one F(1), and two equivalent F(4) atoms to form a mixture of corner and edge-sharing FeO3F3 octahedra. The corner-sharing octahedral tilt angles range from 46-55°. 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 46-50°. 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(5)O3F3 octahedra, and edges with two equivalent Fe(7)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 46-55°. 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)O3F3 octahedra, edges with two equivalent Mg(1)O5F octahedra, and edges with two equivalent Fe(8)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(3) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded to two equivalent Mg(1), one Fe(4), and two equivalent Fe(1) atoms to form distorted OMg2Fe3 trigonal bipyramids that share corners with two equivalent O(8)Mg2Fe3 trigonal bipyramids,  an edgeedge with one O(8)Mg2Fe3 trigonal bipyramid, edges with two equivalent O(2)Mg2Fe3 trigonal bipyramids, and edges with two equivalent O(4)MgFe3 trigonal pyramids. 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 to one Mg(1), one Fe(2), and two equivalent Fe(4) atoms to form distorted OMgFe3 trigonal pyramids that share corners with two equivalent O(4)MgFe3 trigonal pyramids, edges with two equivalent O(2)Mg2Fe3 trigonal bipyramids, and edges with two equivalent O(8)Mg2Fe3 trigonal bipyramids. 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 to two equivalent Mg(1), one Fe(8), and two equivalent Fe(2) atoms to form distorted OMg2Fe3 trigonal bipyramids that share corners with two equivalent O(2)Mg2Fe3 trigonal bipyramids,  an edgeedge with one O(2)Mg2Fe3 trigonal bipyramid, edges with two equivalent O(8)Mg2Fe3 trigonal bipyramids, and edges with two equivalent O(4)MgFe3 trigonal pyramids. 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 distorted 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 T-shaped geometry to one Fe(4) and two equivalent Fe(5) atoms. In the fifth F site, F(5) is bonded in a distorted trigonal planar 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 distorted T-shaped geometry to one Mg(1) and 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   9.848
_cell_length_b   9.711
_cell_length_c   3.074
_cell_angle_alpha   89.879
_cell_angle_beta   90.127
_cell_angle_gamma   87.402
_symmetry_Int_Tables_number   1
_cell_volume   293.626
_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  0.989  0.759  0.010  1.0
  Fe  Fe1  1  0.040  0.035  0.006  1.0
  Fe  Fe2  1  0.997  0.475  0.995  1.0
  Fe  Fe3  1  0.242  0.261  0.501  1.0
  Fe  Fe4  1  0.240  0.743  0.509  1.0
  Fe  Fe5  1  0.517  0.485  0.004  1.0
  Fe  Fe6  1  0.505  0.007  0.005  1.0
  Fe  Fe7  1  0.759  0.270  0.502  1.0
  Fe  Fe8  1  0.724  0.712  0.509  1.0
  O  O9  1  0.094  0.400  0.497  1.0
  O  O10  1  0.073  0.877  0.507  1.0
  O  O11  1  0.184  0.161  0.001  1.0
  O  O12  1  0.164  0.649  0.008  1.0
  O  O13  1  0.591  0.387  0.505  1.0
  O  O14  1  0.643  0.631  0.008  1.0
  O  O15  1  0.844  0.355  0.002  1.0
  O  O16  1  0.912  0.626  0.512  1.0
  F  F17  1  0.348  0.366  0.002  1.0
  F  F18  1  0.342  0.853  0.007  1.0
  F  F19  1  0.418  0.124  0.504  1.0
  F  F20  1  0.408  0.600  0.507  1.0
  F  F21  1  0.584  0.882  0.506  1.0
  F  F22  1  0.667  0.147  0.004  1.0
  F  F23  1  0.805  0.841  0.010  1.0
  F  F24  1  0.903  0.111  0.505  1.0
[/CIF]
.
The crystal structure described by MgFe8(OF)8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(4), two equivalent O(2), two equivalent O(8), and one F(7) atom to form MgO5F octahedra that share edges with two equivalent Mg(1)O5F octahedra, edges with two equivalent Fe(4)O3F3 octahedra, and edges with two equivalent Fe(8)O3F3 octahedra. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(2), and two equivalent F(8) atoms. In the second Fe site, Fe(2) is bonded in a 6-coordinate geometry to one O(4), 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(5)O3F3 octahedra, and edges with two equivalent Fe(3)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 47-50°. 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, edges with two equivalent Mg(1)O5F octahedra, and edges with two equivalent Fe(4)O3F3 octahedra. 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), one F(1), and two equivalent F(4) atoms to form a mixture of corner and edge-sharing FeO3F3 octahedra. The corner-sharing octahedral tilt angles range from 46-55°. 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 46-50°. 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(5)O3F3 octahedra, and edges with two equivalent Fe(7)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 46-55°. 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)O3F3 octahedra, edges with two equivalent Mg(1)O5F octahedra, and edges with two equivalent Fe(8)O3F3 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(3) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded to two equivalent Mg(1), one Fe(4), and two equivalent Fe(1) atoms to form distorted OMg2Fe3 trigonal bipyramids that share corners with two equivalent O(8)Mg2Fe3 trigonal bipyramids,  an edgeedge with one O(8)Mg2Fe3 trigonal bipyramid, edges with two equivalent O(2)Mg2Fe3 trigonal bipyramids, and edges with two equivalent O(4)MgFe3 trigonal pyramids. 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 to one Mg(1), one Fe(2), and two equivalent Fe(4) atoms to form distorted OMgFe3 trigonal pyramids that share corners with two equivalent O(4)MgFe3 trigonal pyramids, edges with two equivalent O(2)Mg2Fe3 trigonal bipyramids, and edges with two equivalent O(8)Mg2Fe3 trigonal bipyramids. 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 to two equivalent Mg(1), one Fe(8), and two equivalent Fe(2) atoms to form distorted OMg2Fe3 trigonal bipyramids that share corners with two equivalent O(2)Mg2Fe3 trigonal bipyramids,  an edgeedge with one O(2)Mg2Fe3 trigonal bipyramid, edges with two equivalent O(8)Mg2Fe3 trigonal bipyramids, and edges with two equivalent O(4)MgFe3 trigonal pyramids. 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 distorted 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 T-shaped geometry to one Fe(4) and two equivalent Fe(5) atoms. In the fifth F site, F(5) is bonded in a distorted trigonal planar 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 distorted T-shaped geometry to one Mg(1) and 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   9.848
_cell_length_b   9.711
_cell_length_c   3.074
_cell_angle_alpha   89.879
_cell_angle_beta   90.127
_cell_angle_gamma   87.402
_symmetry_Int_Tables_number   1
_cell_volume   293.626
_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  0.989  0.759  0.010  1.0
  Fe  Fe1  1  0.040  0.035  0.006  1.0
  Fe  Fe2  1  0.997  0.475  0.995  1.0
  Fe  Fe3  1  0.242  0.261  0.501  1.0
  Fe  Fe4  1  0.240  0.743  0.509  1.0
  Fe  Fe5  1  0.517  0.485  0.004  1.0
  Fe  Fe6  1  0.505  0.007  0.005  1.0
  Fe  Fe7  1  0.759  0.270  0.502  1.0
  Fe  Fe8  1  0.724  0.712  0.509  1.0
  O  O9  1  0.094  0.400  0.497  1.0
  O  O10  1  0.073  0.877  0.507  1.0
  O  O11  1  0.184  0.161  0.001  1.0
  O  O12  1  0.164  0.649  0.008  1.0
  O  O13  1  0.591  0.387  0.505  1.0
  O  O14  1  0.643  0.631  0.008  1.0
  O  O15  1  0.844  0.355  0.002  1.0
  O  O16  1  0.912  0.626  0.512  1.0
  F  F17  1  0.348  0.366  0.002  1.0
  F  F18  1  0.342  0.853  0.007  1.0
  F  F19  1  0.418  0.124  0.504  1.0
  F  F20  1  0.408  0.600  0.507  1.0
  F  F21  1  0.584  0.882  0.506  1.0
  F  F22  1  0.667  0.147  0.004  1.0
  F  F23  1  0.805  0.841  0.010  1.0
  F  F24  1  0.903  0.111  0.505  1.0
[/CIF]
.