The compound described by FeO2 crystallizes in the trigonal R3m space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2) and three equivalent O(1) atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-59°. In the second Fe site, Fe(2) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with three equivalent Fe(1)O4 tetrahedra and edges with four equivalent Fe(2)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1) and three equivalent Fe(2) atoms. In the third O site, O(3) is bonded in a distorted T-shaped geometry to three equivalent Fe(2) atoms. In the fourth O site, O(4) is bonded in a water-like geometry to two equivalent Fe(2) atoms. is represented by the CIF file [CIF]
data_FeO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.816
_cell_length_b   5.816
_cell_length_c   5.816
_cell_angle_alpha   61.554
_cell_angle_beta   61.554
_cell_angle_gamma   61.554
_symmetry_Int_Tables_number   1
_cell_volume   143.980
_cell_formula_units_Z   4
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
  Fe  Fe0  1  0.760  0.760  0.760  1.0
  Fe  Fe1  1  0.885  0.369  0.369  1.0
  Fe  Fe2  1  0.369  0.369  0.885  1.0
  Fe  Fe3  1  0.369  0.885  0.369  1.0
  O  O4  1  0.629  0.155  0.629  1.0
  O  O5  1  0.629  0.629  0.155  1.0
  O  O6  1  0.155  0.629  0.629  1.0
  O  O7  1  0.623  0.623  0.623  1.0
  O  O8  1  0.127  0.127  0.127  1.0
  O  O9  1  0.574  0.128  0.128  1.0
  O  O10  1  0.128  0.128  0.574  1.0
  O  O11  1  0.128  0.574  0.128  1.0
[/CIF]
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The compound described by FeO2 crystallizes in the trigonal R3m space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2) and three equivalent O(1) atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-59°. In the second Fe site, Fe(2) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with three equivalent Fe(1)O4 tetrahedra and edges with four equivalent Fe(2)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1) and three equivalent Fe(2) atoms. In the third O site, O(3) is bonded in a distorted T-shaped geometry to three equivalent Fe(2) atoms. In the fourth O site, O(4) is bonded in a water-like geometry to two equivalent Fe(2) atoms. is represented by the CIF file [CIF]
data_FeO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.816
_cell_length_b   5.816
_cell_length_c   5.816
_cell_angle_alpha   61.554
_cell_angle_beta   61.554
_cell_angle_gamma   61.554
_symmetry_Int_Tables_number   1
_cell_volume   143.980
_cell_formula_units_Z   4
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
  Fe  Fe0  1  0.760  0.760  0.760  1.0
  Fe  Fe1  1  0.885  0.369  0.369  1.0
  Fe  Fe2  1  0.369  0.369  0.885  1.0
  Fe  Fe3  1  0.369  0.885  0.369  1.0
  O  O4  1  0.629  0.155  0.629  1.0
  O  O5  1  0.629  0.629  0.155  1.0
  O  O6  1  0.155  0.629  0.629  1.0
  O  O7  1  0.623  0.623  0.623  1.0
  O  O8  1  0.127  0.127  0.127  1.0
  O  O9  1  0.574  0.128  0.128  1.0
  O  O10  1  0.128  0.128  0.574  1.0
  O  O11  1  0.128  0.574  0.128  1.0
[/CIF]
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