The crystal structure described by Fe8O9 crystallizes in the triclinic P-1 space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 0-10°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 0-13°. In the third Fe site, Fe(3) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 4-12°. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(2), one O(4), one O(5), and two equivalent O(3) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 0-13°. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Fe(1), one Fe(2), one Fe(4), and two equivalent Fe(3) atoms to form OFe5 square pyramids that share  a cornercorner with one O(3)Fe6 octahedra,  a cornercorner with one O(5)Fe6 octahedra, corners with three equivalent O(4)Fe5 square pyramids, corners with four equivalent O(2)Fe5 square pyramids,  an edgeedge with one O(5)Fe6 octahedra, edges with three equivalent O(3)Fe6 octahedra,  an edgeedge with one O(1)Fe5 square pyramid,  an edgeedge with one O(2)Fe5 square pyramid, and edges with two equivalent O(4)Fe5 square pyramids. The corner-sharing octahedral tilt angles are 3°. In the second O site, O(2) is bonded to one Fe(2), one Fe(3), one Fe(4), and two equivalent Fe(1) atoms to form OFe5 square pyramids that share corners with two equivalent O(3)Fe6 octahedra, corners with three equivalent O(4)Fe5 square pyramids, corners with four equivalent O(1)Fe5 square pyramids, edges with two equivalent O(5)Fe6 octahedra, edges with three equivalent O(3)Fe6 octahedra,  an edgeedge with one O(1)Fe5 square pyramid,  an edgeedge with one O(2)Fe5 square pyramid, and  an edgeedge with one O(4)Fe5 square pyramid. The corner-sharing octahedral tilt angles range from 5-9°. In the third O site, O(3) is bonded to one Fe(2), one Fe(3), two equivalent Fe(1), and two equivalent Fe(4) atoms to form OFe6 octahedra that share  a cornercorner with one O(5)Fe6 octahedra,  a cornercorner with one O(1)Fe5 square pyramid, corners with two equivalent O(2)Fe5 square pyramids, corners with two equivalent O(4)Fe5 square pyramids, edges with two equivalent O(3)Fe6 octahedra, edges with two equivalent O(5)Fe6 octahedra, edges with two equivalent O(4)Fe5 square pyramids, edges with three equivalent O(1)Fe5 square pyramids, and edges with three equivalent O(2)Fe5 square pyramids. The corner-sharing octahedral tilt angles are 8°. In the fourth O site, O(4) is bonded to one Fe(4), two equivalent Fe(2), and two equivalent Fe(3) atoms to form OFe5 square pyramids that share  a cornercorner with one O(5)Fe6 octahedra, corners with two equivalent O(3)Fe6 octahedra, corners with three equivalent O(1)Fe5 square pyramids, corners with three equivalent O(2)Fe5 square pyramids,  an edgeedge with one O(5)Fe6 octahedra, edges with two equivalent O(3)Fe6 octahedra,  an edgeedge with one O(2)Fe5 square pyramid, edges with two equivalent O(1)Fe5 square pyramids, and edges with two equivalent O(4)Fe5 square pyramids. The corner-sharing octahedral tilt angles range from 6-10°. In the fifth O site, O(5) is bonded to two equivalent Fe(1), two equivalent Fe(2), and two equivalent Fe(4) atoms to form OFe6 octahedra that share corners with two equivalent O(3)Fe6 octahedra, corners with two equivalent O(1)Fe5 square pyramids, corners with two equivalent O(4)Fe5 square pyramids, edges with four equivalent O(3)Fe6 octahedra, edges with two equivalent O(1)Fe5 square pyramids, edges with two equivalent O(4)Fe5 square pyramids, and edges with four equivalent O(2)Fe5 square pyramids. The corner-sharing octahedral tilt angles are 8°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe8O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.311
_cell_length_b   5.353
_cell_length_c   6.829
_cell_angle_alpha   82.151
_cell_angle_beta   74.669
_cell_angle_gamma   80.753
_symmetry_Int_Tables_number   1
_cell_volume   183.881
_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
  Fe  Fe0  1  0.891  0.790  0.424  1.0
  Fe  Fe1  1  0.450  0.892  0.214  1.0
  Fe  Fe2  1  0.790  0.551  0.882  1.0
  Fe  Fe3  1  0.324  0.682  0.670  1.0
  Fe  Fe4  1  0.210  0.449  0.118  1.0
  Fe  Fe5  1  0.676  0.318  0.330  1.0
  Fe  Fe6  1  0.550  0.108  0.786  1.0
  Fe  Fe7  1  0.109  0.210  0.576  1.0
  O  O8  1  0.834  0.647  0.156  1.0
  O  O9  1  0.923  0.880  0.716  1.0
  O  O10  1  0.728  0.451  0.612  1.0
  O  O11  1  0.414  0.744  0.943  1.0
  O  O12  1  0.272  0.549  0.388  1.0
  O  O13  1  0.586  0.256  0.057  1.0
  O  O14  1  0.077  0.120  0.284  1.0
  O  O15  1  0.166  0.353  0.844  1.0
  O  O16  1  0.500  0.000  0.500  1.0
[/CIF]
.
The crystal structure described by Fe8O9 crystallizes in the triclinic P-1 space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 0-10°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 0-13°. In the third Fe site, Fe(3) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 4-12°. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(2), one O(4), one O(5), and two equivalent O(3) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 0-13°. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Fe(1), one Fe(2), one Fe(4), and two equivalent Fe(3) atoms to form OFe5 square pyramids that share  a cornercorner with one O(3)Fe6 octahedra,  a cornercorner with one O(5)Fe6 octahedra, corners with three equivalent O(4)Fe5 square pyramids, corners with four equivalent O(2)Fe5 square pyramids,  an edgeedge with one O(5)Fe6 octahedra, edges with three equivalent O(3)Fe6 octahedra,  an edgeedge with one O(1)Fe5 square pyramid,  an edgeedge with one O(2)Fe5 square pyramid, and edges with two equivalent O(4)Fe5 square pyramids. The corner-sharing octahedral tilt angles are 3°. In the second O site, O(2) is bonded to one Fe(2), one Fe(3), one Fe(4), and two equivalent Fe(1) atoms to form OFe5 square pyramids that share corners with two equivalent O(3)Fe6 octahedra, corners with three equivalent O(4)Fe5 square pyramids, corners with four equivalent O(1)Fe5 square pyramids, edges with two equivalent O(5)Fe6 octahedra, edges with three equivalent O(3)Fe6 octahedra,  an edgeedge with one O(1)Fe5 square pyramid,  an edgeedge with one O(2)Fe5 square pyramid, and  an edgeedge with one O(4)Fe5 square pyramid. The corner-sharing octahedral tilt angles range from 5-9°. In the third O site, O(3) is bonded to one Fe(2), one Fe(3), two equivalent Fe(1), and two equivalent Fe(4) atoms to form OFe6 octahedra that share  a cornercorner with one O(5)Fe6 octahedra,  a cornercorner with one O(1)Fe5 square pyramid, corners with two equivalent O(2)Fe5 square pyramids, corners with two equivalent O(4)Fe5 square pyramids, edges with two equivalent O(3)Fe6 octahedra, edges with two equivalent O(5)Fe6 octahedra, edges with two equivalent O(4)Fe5 square pyramids, edges with three equivalent O(1)Fe5 square pyramids, and edges with three equivalent O(2)Fe5 square pyramids. The corner-sharing octahedral tilt angles are 8°. In the fourth O site, O(4) is bonded to one Fe(4), two equivalent Fe(2), and two equivalent Fe(3) atoms to form OFe5 square pyramids that share  a cornercorner with one O(5)Fe6 octahedra, corners with two equivalent O(3)Fe6 octahedra, corners with three equivalent O(1)Fe5 square pyramids, corners with three equivalent O(2)Fe5 square pyramids,  an edgeedge with one O(5)Fe6 octahedra, edges with two equivalent O(3)Fe6 octahedra,  an edgeedge with one O(2)Fe5 square pyramid, edges with two equivalent O(1)Fe5 square pyramids, and edges with two equivalent O(4)Fe5 square pyramids. The corner-sharing octahedral tilt angles range from 6-10°. In the fifth O site, O(5) is bonded to two equivalent Fe(1), two equivalent Fe(2), and two equivalent Fe(4) atoms to form OFe6 octahedra that share corners with two equivalent O(3)Fe6 octahedra, corners with two equivalent O(1)Fe5 square pyramids, corners with two equivalent O(4)Fe5 square pyramids, edges with four equivalent O(3)Fe6 octahedra, edges with two equivalent O(1)Fe5 square pyramids, edges with two equivalent O(4)Fe5 square pyramids, and edges with four equivalent O(2)Fe5 square pyramids. The corner-sharing octahedral tilt angles are 8°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe8O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.311
_cell_length_b   5.353
_cell_length_c   6.829
_cell_angle_alpha   82.151
_cell_angle_beta   74.669
_cell_angle_gamma   80.753
_symmetry_Int_Tables_number   1
_cell_volume   183.881
_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
  Fe  Fe0  1  0.891  0.790  0.424  1.0
  Fe  Fe1  1  0.450  0.892  0.214  1.0
  Fe  Fe2  1  0.790  0.551  0.882  1.0
  Fe  Fe3  1  0.324  0.682  0.670  1.0
  Fe  Fe4  1  0.210  0.449  0.118  1.0
  Fe  Fe5  1  0.676  0.318  0.330  1.0
  Fe  Fe6  1  0.550  0.108  0.786  1.0
  Fe  Fe7  1  0.109  0.210  0.576  1.0
  O  O8  1  0.834  0.647  0.156  1.0
  O  O9  1  0.923  0.880  0.716  1.0
  O  O10  1  0.728  0.451  0.612  1.0
  O  O11  1  0.414  0.744  0.943  1.0
  O  O12  1  0.272  0.549  0.388  1.0
  O  O13  1  0.586  0.256  0.057  1.0
  O  O14  1  0.077  0.120  0.284  1.0
  O  O15  1  0.166  0.353  0.844  1.0
  O  O16  1  0.500  0.000  0.500  1.0
[/CIF]
.