The compound described by Mg(FeO2)4 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(4), one O(8), two equivalent O(1), and two equivalent O(6) atoms to form distorted MgO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with three equivalent Fe(4)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Fe(2)O6 octahedra, and  a faceface with one Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-43°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), one O(5), two equivalent O(3), and two equivalent O(7) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 51-52°. In the second Fe site, Fe(2) is bonded to one O(1), one O(6), two equivalent O(4), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with four equivalent Fe(3)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(4)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. In the third Fe site, Fe(3) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-53°. In the fourth Fe site, Fe(4) is bonded to one O(3), one O(8), two equivalent O(2), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-52°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Fe(2), and two equivalent Fe(3) atoms to form distorted OMg2Fe3 trigonal bipyramids that share corners with three equivalent O(6)Mg2Fe3 square pyramids, corners with two equivalent O(4)MgFe3 trigonal pyramids,  an edgeedge with one O(6)Mg2Fe3 square pyramid, edges with two equivalent O(1)Mg2Fe3 trigonal bipyramids, edges with two equivalent O(4)MgFe3 trigonal pyramids, and edges with two equivalent O(8)MgFe3 trigonal pyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(4) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(4) and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded to one Mg(1), one Fe(3), and two equivalent Fe(2) atoms to form OMgFe3 trigonal pyramids that share corners with two equivalent O(1)Mg2Fe3 trigonal bipyramids, corners with two equivalent O(4)MgFe3 trigonal pyramids, corners with three equivalent O(8)MgFe3 trigonal pyramids, edges with two equivalent O(6)Mg2Fe3 square pyramids, edges with two equivalent O(1)Mg2Fe3 trigonal bipyramids, and  an edgeedge with one O(8)MgFe3 trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Fe(1) and two equivalent Fe(3) atoms. In the sixth O site, O(6) is bonded to two equivalent Mg(1), one Fe(2), and two equivalent Fe(4) atoms to form OMg2Fe3 square pyramids that share corners with three equivalent O(1)Mg2Fe3 trigonal bipyramids, corners with two equivalent O(8)MgFe3 trigonal pyramids, edges with two equivalent O(6)Mg2Fe3 square pyramids,  an edgeedge with one O(1)Mg2Fe3 trigonal bipyramid, edges with two equivalent O(4)MgFe3 trigonal pyramids, and edges with two equivalent O(8)MgFe3 trigonal pyramids. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Fe(3) and two equivalent Fe(1) atoms. In the eighth O site, O(8) is bonded to one Mg(1), one Fe(4), and two equivalent Fe(2) atoms to form distorted OMgFe3 trigonal pyramids that share corners with two equivalent O(6)Mg2Fe3 square pyramids, corners with two equivalent O(8)MgFe3 trigonal pyramids, corners with three equivalent O(4)MgFe3 trigonal pyramids, edges with two equivalent O(6)Mg2Fe3 square pyramids, edges with two equivalent O(1)Mg2Fe3 trigonal bipyramids, and  an edgeedge with one O(4)MgFe3 trigonal pyramid. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg(FeO2)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.028
_cell_length_b   5.175
_cell_length_c   9.263
_cell_angle_alpha   90.231
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   145.159
_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  0.750  0.437  0.930  1.0
  Fe  Fe1  1  0.250  0.556  0.358  1.0
  Fe  Fe2  1  0.250  0.940  0.856  1.0
  Fe  Fe3  1  0.750  0.426  0.628  1.0
  Fe  Fe4  1  0.750  0.046  0.154  1.0
  O  O5  1  0.250  0.587  0.765  1.0
  O  O6  1  0.250  0.870  0.246  1.0
  O  O7  1  0.750  0.385  0.256  1.0
  O  O8  1  0.750  0.141  0.765  1.0
  O  O9  1  0.250  0.298  0.515  1.0
  O  O10  1  0.250  0.224  0.020  1.0
  O  O11  1  0.750  0.688  0.483  1.0
  O  O12  1  0.750  0.805  0.980  1.0
[/CIF]
.
The compound described by Mg(FeO2)4 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(4), one O(8), two equivalent O(1), and two equivalent O(6) atoms to form distorted MgO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with three equivalent Fe(4)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Fe(2)O6 octahedra, and  a faceface with one Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-43°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), one O(5), two equivalent O(3), and two equivalent O(7) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 51-52°. In the second Fe site, Fe(2) is bonded to one O(1), one O(6), two equivalent O(4), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with four equivalent Fe(3)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(4)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. In the third Fe site, Fe(3) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-53°. In the fourth Fe site, Fe(4) is bonded to one O(3), one O(8), two equivalent O(2), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-52°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Fe(2), and two equivalent Fe(3) atoms to form distorted OMg2Fe3 trigonal bipyramids that share corners with three equivalent O(6)Mg2Fe3 square pyramids, corners with two equivalent O(4)MgFe3 trigonal pyramids,  an edgeedge with one O(6)Mg2Fe3 square pyramid, edges with two equivalent O(1)Mg2Fe3 trigonal bipyramids, edges with two equivalent O(4)MgFe3 trigonal pyramids, and edges with two equivalent O(8)MgFe3 trigonal pyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(4) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Fe(4) and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded to one Mg(1), one Fe(3), and two equivalent Fe(2) atoms to form OMgFe3 trigonal pyramids that share corners with two equivalent O(1)Mg2Fe3 trigonal bipyramids, corners with two equivalent O(4)MgFe3 trigonal pyramids, corners with three equivalent O(8)MgFe3 trigonal pyramids, edges with two equivalent O(6)Mg2Fe3 square pyramids, edges with two equivalent O(1)Mg2Fe3 trigonal bipyramids, and  an edgeedge with one O(8)MgFe3 trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Fe(1) and two equivalent Fe(3) atoms. In the sixth O site, O(6) is bonded to two equivalent Mg(1), one Fe(2), and two equivalent Fe(4) atoms to form OMg2Fe3 square pyramids that share corners with three equivalent O(1)Mg2Fe3 trigonal bipyramids, corners with two equivalent O(8)MgFe3 trigonal pyramids, edges with two equivalent O(6)Mg2Fe3 square pyramids,  an edgeedge with one O(1)Mg2Fe3 trigonal bipyramid, edges with two equivalent O(4)MgFe3 trigonal pyramids, and edges with two equivalent O(8)MgFe3 trigonal pyramids. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Fe(3) and two equivalent Fe(1) atoms. In the eighth O site, O(8) is bonded to one Mg(1), one Fe(4), and two equivalent Fe(2) atoms to form distorted OMgFe3 trigonal pyramids that share corners with two equivalent O(6)Mg2Fe3 square pyramids, corners with two equivalent O(8)MgFe3 trigonal pyramids, corners with three equivalent O(4)MgFe3 trigonal pyramids, edges with two equivalent O(6)Mg2Fe3 square pyramids, edges with two equivalent O(1)Mg2Fe3 trigonal bipyramids, and  an edgeedge with one O(4)MgFe3 trigonal pyramid. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg(FeO2)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.028
_cell_length_b   5.175
_cell_length_c   9.263
_cell_angle_alpha   90.231
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   145.159
_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  0.750  0.437  0.930  1.0
  Fe  Fe1  1  0.250  0.556  0.358  1.0
  Fe  Fe2  1  0.250  0.940  0.856  1.0
  Fe  Fe3  1  0.750  0.426  0.628  1.0
  Fe  Fe4  1  0.750  0.046  0.154  1.0
  O  O5  1  0.250  0.587  0.765  1.0
  O  O6  1  0.250  0.870  0.246  1.0
  O  O7  1  0.750  0.385  0.256  1.0
  O  O8  1  0.750  0.141  0.765  1.0
  O  O9  1  0.250  0.298  0.515  1.0
  O  O10  1  0.250  0.224  0.020  1.0
  O  O11  1  0.750  0.688  0.483  1.0
  O  O12  1  0.750  0.805  0.980  1.0
[/CIF]
.