The compound described by Mg(FeO2)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(4)O6 octahedra, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 42°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(7), two equivalent O(4), and two equivalent O(5) atoms to form distorted FeO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(4)O6 octahedra, and edges with two equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-74°. In the second Fe site, Fe(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Fe(2)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. In the third Fe site, Fe(3) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms. In the fourth Fe site, Fe(4) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(4)O6 octahedra, and edges with two equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 52-53°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Fe(3), and two equivalent Fe(4) atoms to form OMgFe3 trigonal pyramids that share  a cornercorner with one O(4)MgFe3 tetrahedra, corners with two equivalent O(1)MgFe3 trigonal pyramids, and edges with two equivalent O(3)Mg2Fe3 trigonal bipyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Mg(1) and two equivalent Fe(3) atoms. In the third O site, O(3) is bonded to two equivalent Mg(1), one Fe(4), and two equivalent Fe(2) atoms to form distorted OMg2Fe3 trigonal bipyramids that share edges with two equivalent O(4)MgFe3 tetrahedra, edges with two equivalent O(3)Mg2Fe3 trigonal bipyramids, and edges with two equivalent O(1)MgFe3 trigonal pyramids. In the fourth O site, O(4) is bonded to one Mg(1), one Fe(2), and two equivalent Fe(1) atoms to form distorted OMgFe3 tetrahedra that share corners with two equivalent O(4)MgFe3 tetrahedra,  a cornercorner with one O(1)MgFe3 trigonal pyramid, and edges with two equivalent O(3)Mg2Fe3 trigonal bipyramids. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Fe(4) and two equivalent Fe(1) atoms. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Fe(3) and two equivalent Fe(2) atoms. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Fe(1) and two equivalent Fe(4) atoms. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Fe(2) and two equivalent Fe(3) atoms. is represented by the CIF card [CIF]
data_Mg(FeO2)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.989
_cell_length_b   8.119
_cell_length_c   7.739
_cell_angle_alpha   84.300
_cell_angle_beta   82.023
_cell_angle_gamma   80.057
_symmetry_Int_Tables_number   1
_cell_volume   182.628
_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  0.056  0.475  0.533  1.0
  Fe  Fe1  1  0.744  0.130  0.453  1.0
  Fe  Fe2  1  0.172  0.494  0.180  1.0
  Fe  Fe3  1  0.757  0.565  0.852  1.0
  Fe  Fe4  1  0.385  0.809  0.477  1.0
  O  O5  1  0.866  0.710  0.630  1.0
  O  O6  1  0.509  0.435  0.714  1.0
  O  O7  1  0.548  0.581  0.349  1.0
  O  O8  1  0.201  0.284  0.370  1.0
  O  O9  1  0.238  0.038  0.589  1.0
  O  O10  1  0.766  0.403  0.052  1.0
  O  O11  1  0.886  0.916  0.342  1.0
  O  O12  1  0.144  0.662  0.972  1.0
[/CIF]
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The compound described by Mg(FeO2)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(4)O6 octahedra, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 42°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(7), two equivalent O(4), and two equivalent O(5) atoms to form distorted FeO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(4)O6 octahedra, and edges with two equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-74°. In the second Fe site, Fe(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Fe(2)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. In the third Fe site, Fe(3) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms. In the fourth Fe site, Fe(4) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Fe(4)O6 octahedra, and edges with two equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 52-53°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Fe(3), and two equivalent Fe(4) atoms to form OMgFe3 trigonal pyramids that share  a cornercorner with one O(4)MgFe3 tetrahedra, corners with two equivalent O(1)MgFe3 trigonal pyramids, and edges with two equivalent O(3)Mg2Fe3 trigonal bipyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Mg(1) and two equivalent Fe(3) atoms. In the third O site, O(3) is bonded to two equivalent Mg(1), one Fe(4), and two equivalent Fe(2) atoms to form distorted OMg2Fe3 trigonal bipyramids that share edges with two equivalent O(4)MgFe3 tetrahedra, edges with two equivalent O(3)Mg2Fe3 trigonal bipyramids, and edges with two equivalent O(1)MgFe3 trigonal pyramids. In the fourth O site, O(4) is bonded to one Mg(1), one Fe(2), and two equivalent Fe(1) atoms to form distorted OMgFe3 tetrahedra that share corners with two equivalent O(4)MgFe3 tetrahedra,  a cornercorner with one O(1)MgFe3 trigonal pyramid, and edges with two equivalent O(3)Mg2Fe3 trigonal bipyramids. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Fe(4) and two equivalent Fe(1) atoms. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Fe(3) and two equivalent Fe(2) atoms. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Fe(1) and two equivalent Fe(4) atoms. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Fe(2) and two equivalent Fe(3) atoms. is represented by the CIF card [CIF]
data_Mg(FeO2)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.989
_cell_length_b   8.119
_cell_length_c   7.739
_cell_angle_alpha   84.300
_cell_angle_beta   82.023
_cell_angle_gamma   80.057
_symmetry_Int_Tables_number   1
_cell_volume   182.628
_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  0.056  0.475  0.533  1.0
  Fe  Fe1  1  0.744  0.130  0.453  1.0
  Fe  Fe2  1  0.172  0.494  0.180  1.0
  Fe  Fe3  1  0.757  0.565  0.852  1.0
  Fe  Fe4  1  0.385  0.809  0.477  1.0
  O  O5  1  0.866  0.710  0.630  1.0
  O  O6  1  0.509  0.435  0.714  1.0
  O  O7  1  0.548  0.581  0.349  1.0
  O  O8  1  0.201  0.284  0.370  1.0
  O  O9  1  0.238  0.038  0.589  1.0
  O  O10  1  0.766  0.403  0.052  1.0
  O  O11  1  0.886  0.916  0.342  1.0
  O  O12  1  0.144  0.662  0.972  1.0
[/CIF]
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