The compound described by MgFe8(OF)8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(3), one O(5), one F(2), one F(5), and one F(8) atom to form distorted MgO2F3 trigonal bipyramids that share  a cornercorner with one Fe(5)O3F2 trigonal bipyramid, corners with two equivalent Fe(1)O3F2 trigonal bipyramids, corners with two equivalent Fe(6)O3F2 trigonal bipyramids, and edges with two equivalent Fe(7)O3F2 trigonal bipyramids. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), one O(6), one O(8), one F(1), and one F(8) atom to form distorted FeO3F2 trigonal bipyramids that share corners with two equivalent Mg(1)O2F3 trigonal bipyramids, corners with two equivalent Fe(5)O3F2 trigonal bipyramids, corners with two equivalent Fe(7)O3F2 trigonal bipyramids, and  an edgeedge with one Fe(2)O3F2 trigonal bipyramid. In the second Fe site, Fe(2) is bonded to one O(1), one O(4), one O(8), one F(1), and one F(6) atom to form a mixture of distorted corner and edge-sharing FeO3F2 trigonal bipyramids. In the third Fe site, Fe(3) is bonded to one O(1), one O(2), one O(7), one F(6), and one F(7) atom to form a mixture of distorted corner and edge-sharing FeO3F2 square pyramids. In the fourth Fe site, Fe(4) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one F(7), and one F(8) atom. In the fifth Fe site, Fe(5) is bonded to one O(4), one O(6), one O(8), one F(2), and one F(4) atom to form FeO3F2 trigonal bipyramids that share  a cornercorner with one Mg(1)O2F3 trigonal bipyramid, corners with two equivalent Fe(1)O3F2 trigonal bipyramids, corners with two equivalent Fe(2)O3F2 trigonal bipyramids,  an edgeedge with one Fe(7)O3F2 trigonal bipyramid, and  an edgeedge with one Fe(8)O3F2 trigonal bipyramid. In the sixth Fe site, Fe(6) is bonded to one O(2), one O(5), one O(7), one F(3), and one F(5) atom to form FeO3F2 trigonal bipyramids that share corners with two equivalent Fe(3)O3F2 square pyramids, corners with two equivalent Mg(1)O2F3 trigonal bipyramids,  an edgeedge with one Fe(7)O3F2 trigonal bipyramid, and  an edgeedge with one Fe(8)O3F2 trigonal bipyramid. In the seventh Fe site, Fe(7) is bonded to one O(3), one O(5), one O(6), one F(2), and one F(5) atom to form distorted FeO3F2 trigonal bipyramids that share corners with two equivalent Fe(1)O3F2 trigonal bipyramids,  an edgeedge with one Fe(5)O3F2 trigonal bipyramid,  an edgeedge with one Fe(6)O3F2 trigonal bipyramid, and edges with two equivalent Mg(1)O2F3 trigonal bipyramids. In the eighth Fe site, Fe(8) is bonded to one O(1), one O(4), one O(7), one F(3), and one F(4) atom to form a mixture of distorted corner and edge-sharing FeO3F2 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(2), one Fe(3), and one Fe(8) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(4), and one Fe(6) atom. In the third O site, O(3) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Fe(1), one Fe(4), and one Fe(7) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Fe(2), one Fe(5), and one Fe(8) atom. In the fifth O site, O(5) is bonded in a distorted see-saw-like geometry to one Mg(1), one Fe(4), one Fe(6), and one Fe(7) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(5), and one Fe(7) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(6), and one Fe(8) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Fe(5) atom. There are eight inequivalent F sites. In the first F site, F(1) is bonded in a water-like geometry to one Fe(1) and one Fe(2) atom. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(5), and one Fe(7) atom. In the third F site, F(3) is bonded in an L-shaped geometry to one Fe(6) and one Fe(8) atom. In the fourth F site, F(4) is bonded in a water-like geometry to one Fe(5) and one Fe(8) atom. In the fifth F site, F(5) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(6), and one Fe(7) atom. In the sixth F site, F(6) is bonded in a water-like geometry to one Fe(2) and one Fe(3) atom. In the seventh F site, F(7) is bonded in an L-shaped geometry to one Fe(3) and one Fe(4) atom. In the eighth F site, F(8) is bonded in a trigonal non-coplanar geometry to one Mg(1), one Fe(1), and one Fe(4) atom. is represented by the CIF file [CIF]
data_MgFe8(OF)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.375
_cell_length_b   5.318
_cell_length_c   11.582
_cell_angle_alpha   89.023
_cell_angle_beta   87.618
_cell_angle_gamma   93.100
_symmetry_Int_Tables_number   1
_cell_volume   330.214
_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  0.492  0.064  0.847  1.0
  Fe  Fe1  1  0.945  0.918  0.008  1.0
  Fe  Fe2  1  0.098  0.061  0.248  1.0
  Fe  Fe3  1  0.943  0.890  0.494  1.0
  Fe  Fe4  1  0.056  0.042  0.735  1.0
  Fe  Fe5  1  0.623  0.412  0.128  1.0
  Fe  Fe6  1  0.412  0.563  0.625  1.0
  Fe  Fe7  1  0.399  0.566  0.893  1.0
  Fe  Fe8  1  0.432  0.568  0.368  1.0
  O  O9  1  0.182  0.812  0.366  1.0
  O  O10  1  0.144  0.779  0.619  1.0
  O  O11  1  0.179  0.851  0.884  1.0
  O  O12  1  0.362  0.319  0.246  1.0
  O  O13  1  0.344  0.328  0.754  1.0
  O  O14  1  0.676  0.671  0.006  1.0
  O  O15  1  0.641  0.677  0.496  1.0
  O  O16  1  0.879  0.175  0.124  1.0
  F  F17  1  0.172  0.804  0.127  1.0
  F  F18  1  0.410  0.242  0.002  1.0
  F  F19  1  0.290  0.339  0.496  1.0
  F  F20  1  0.704  0.668  0.249  1.0
  F  F21  1  0.606  0.781  0.750  1.0
  F  F22  1  0.857  0.150  0.370  1.0
  F  F23  1  0.838  0.151  0.603  1.0
  F  F24  1  0.830  0.166  0.879  1.0
[/CIF]
.
The compound described by MgFe8(OF)8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(3), one O(5), one F(2), one F(5), and one F(8) atom to form distorted MgO2F3 trigonal bipyramids that share  a cornercorner with one Fe(5)O3F2 trigonal bipyramid, corners with two equivalent Fe(1)O3F2 trigonal bipyramids, corners with two equivalent Fe(6)O3F2 trigonal bipyramids, and edges with two equivalent Fe(7)O3F2 trigonal bipyramids. There are eight inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), one O(6), one O(8), one F(1), and one F(8) atom to form distorted FeO3F2 trigonal bipyramids that share corners with two equivalent Mg(1)O2F3 trigonal bipyramids, corners with two equivalent Fe(5)O3F2 trigonal bipyramids, corners with two equivalent Fe(7)O3F2 trigonal bipyramids, and  an edgeedge with one Fe(2)O3F2 trigonal bipyramid. In the second Fe site, Fe(2) is bonded to one O(1), one O(4), one O(8), one F(1), and one F(6) atom to form a mixture of distorted corner and edge-sharing FeO3F2 trigonal bipyramids. In the third Fe site, Fe(3) is bonded to one O(1), one O(2), one O(7), one F(6), and one F(7) atom to form a mixture of distorted corner and edge-sharing FeO3F2 square pyramids. In the fourth Fe site, Fe(4) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one F(7), and one F(8) atom. In the fifth Fe site, Fe(5) is bonded to one O(4), one O(6), one O(8), one F(2), and one F(4) atom to form FeO3F2 trigonal bipyramids that share  a cornercorner with one Mg(1)O2F3 trigonal bipyramid, corners with two equivalent Fe(1)O3F2 trigonal bipyramids, corners with two equivalent Fe(2)O3F2 trigonal bipyramids,  an edgeedge with one Fe(7)O3F2 trigonal bipyramid, and  an edgeedge with one Fe(8)O3F2 trigonal bipyramid. In the sixth Fe site, Fe(6) is bonded to one O(2), one O(5), one O(7), one F(3), and one F(5) atom to form FeO3F2 trigonal bipyramids that share corners with two equivalent Fe(3)O3F2 square pyramids, corners with two equivalent Mg(1)O2F3 trigonal bipyramids,  an edgeedge with one Fe(7)O3F2 trigonal bipyramid, and  an edgeedge with one Fe(8)O3F2 trigonal bipyramid. In the seventh Fe site, Fe(7) is bonded to one O(3), one O(5), one O(6), one F(2), and one F(5) atom to form distorted FeO3F2 trigonal bipyramids that share corners with two equivalent Fe(1)O3F2 trigonal bipyramids,  an edgeedge with one Fe(5)O3F2 trigonal bipyramid,  an edgeedge with one Fe(6)O3F2 trigonal bipyramid, and edges with two equivalent Mg(1)O2F3 trigonal bipyramids. In the eighth Fe site, Fe(8) is bonded to one O(1), one O(4), one O(7), one F(3), and one F(4) atom to form a mixture of distorted corner and edge-sharing FeO3F2 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(2), one Fe(3), and one Fe(8) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(4), and one Fe(6) atom. In the third O site, O(3) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Fe(1), one Fe(4), and one Fe(7) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Fe(2), one Fe(5), and one Fe(8) atom. In the fifth O site, O(5) is bonded in a distorted see-saw-like geometry to one Mg(1), one Fe(4), one Fe(6), and one Fe(7) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(5), and one Fe(7) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(6), and one Fe(8) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Fe(5) atom. There are eight inequivalent F sites. In the first F site, F(1) is bonded in a water-like geometry to one Fe(1) and one Fe(2) atom. In the second F site, F(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(5), and one Fe(7) atom. In the third F site, F(3) is bonded in an L-shaped geometry to one Fe(6) and one Fe(8) atom. In the fourth F site, F(4) is bonded in a water-like geometry to one Fe(5) and one Fe(8) atom. In the fifth F site, F(5) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(6), and one Fe(7) atom. In the sixth F site, F(6) is bonded in a water-like geometry to one Fe(2) and one Fe(3) atom. In the seventh F site, F(7) is bonded in an L-shaped geometry to one Fe(3) and one Fe(4) atom. In the eighth F site, F(8) is bonded in a trigonal non-coplanar geometry to one Mg(1), one Fe(1), and one Fe(4) atom. is represented by the CIF file [CIF]
data_MgFe8(OF)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.375
_cell_length_b   5.318
_cell_length_c   11.582
_cell_angle_alpha   89.023
_cell_angle_beta   87.618
_cell_angle_gamma   93.100
_symmetry_Int_Tables_number   1
_cell_volume   330.214
_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  0.492  0.064  0.847  1.0
  Fe  Fe1  1  0.945  0.918  0.008  1.0
  Fe  Fe2  1  0.098  0.061  0.248  1.0
  Fe  Fe3  1  0.943  0.890  0.494  1.0
  Fe  Fe4  1  0.056  0.042  0.735  1.0
  Fe  Fe5  1  0.623  0.412  0.128  1.0
  Fe  Fe6  1  0.412  0.563  0.625  1.0
  Fe  Fe7  1  0.399  0.566  0.893  1.0
  Fe  Fe8  1  0.432  0.568  0.368  1.0
  O  O9  1  0.182  0.812  0.366  1.0
  O  O10  1  0.144  0.779  0.619  1.0
  O  O11  1  0.179  0.851  0.884  1.0
  O  O12  1  0.362  0.319  0.246  1.0
  O  O13  1  0.344  0.328  0.754  1.0
  O  O14  1  0.676  0.671  0.006  1.0
  O  O15  1  0.641  0.677  0.496  1.0
  O  O16  1  0.879  0.175  0.124  1.0
  F  F17  1  0.172  0.804  0.127  1.0
  F  F18  1  0.410  0.242  0.002  1.0
  F  F19  1  0.290  0.339  0.496  1.0
  F  F20  1  0.704  0.668  0.249  1.0
  F  F21  1  0.606  0.781  0.750  1.0
  F  F22  1  0.857  0.150  0.370  1.0
  F  F23  1  0.838  0.151  0.603  1.0
  F  F24  1  0.830  0.166  0.879  1.0
[/CIF]
.