The crystal structure described by Cr8O21 crystallizes in the triclinic P-1 space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 5-coordinate geometry to one O(10), one O(3), one O(8), and two equivalent O(5) atoms. In the second Cr site, Cr(2) is bonded in a 8-coordinate geometry to one O(11), one O(2), one O(6), one O(7), two equivalent O(1), and two equivalent O(4) atoms. In the third Cr site, Cr(3) is bonded in a 4-coordinate geometry to one O(3), one O(6), one O(7), and one O(9) atom. In the fourth Cr site, Cr(4) is bonded in a 3-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(11) atoms. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Cr(4) and two equivalent Cr(2) atoms. In the second O site, O(2) is bonded in an L-shaped geometry to one Cr(2) and one Cr(4) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Cr(1) and one Cr(3) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Cr(4) and two equivalent Cr(2) atoms. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Cr(1) atoms. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Cr(2) and one Cr(3) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Cr(2) and one Cr(3) atom. In the eighth O site, O(8) is bonded in a single-bond geometry to one Cr(1) atom. In the ninth O site, O(9) is bonded in a single-bond geometry to one Cr(3) atom. In the tenth O site, O(10) is bonded in a linear geometry to two equivalent Cr(1) atoms. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Cr(2) and two equivalent Cr(4) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Cr8O21
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.458
_cell_length_b   6.748
_cell_length_c   12.889
_cell_angle_alpha   105.035
_cell_angle_beta   87.482
_cell_angle_gamma   102.918
_symmetry_Int_Tables_number   1
_cell_volume   446.872
_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
  Cr  Cr0  1  0.735  0.678  0.528  1.0
  Cr  Cr1  1  0.859  0.712  0.074  1.0
  Cr  Cr2  1  0.653  0.613  0.749  1.0
  Cr  Cr3  1  0.300  0.862  0.904  1.0
  Cr  Cr4  1  0.700  0.138  0.096  1.0
  Cr  Cr5  1  0.141  0.288  0.926  1.0
  Cr  Cr6  1  0.347  0.387  0.251  1.0
  Cr  Cr7  1  0.265  0.322  0.472  1.0
  O  O8  1  0.909  0.047  0.055  1.0
  O  O9  1  0.634  0.912  0.220  1.0
  O  O10  1  0.375  0.297  0.382  1.0
  O  O11  1  0.832  0.412  0.077  1.0
  O  O12  1  0.023  0.459  0.422  1.0
  O  O13  1  0.369  0.486  0.803  1.0
  O  O14  1  0.847  0.398  0.826  1.0
  O  O15  1  0.189  0.037  0.581  1.0
  O  O16  1  0.153  0.602  0.174  1.0
  O  O17  1  0.761  0.864  0.741  1.0
  O  O18  1  0.625  0.703  0.618  1.0
  O  O19  1  0.500  0.500  0.500  1.0
  O  O20  1  0.437  0.181  0.023  1.0
  O  O21  1  0.631  0.514  0.197  1.0
  O  O22  1  0.811  0.963  0.419  1.0
  O  O23  1  0.239  0.136  0.259  1.0
  O  O24  1  0.168  0.588  0.923  1.0
  O  O25  1  0.977  0.541  0.578  1.0
  O  O26  1  0.366  0.088  0.780  1.0
  O  O27  1  0.563  0.819  0.977  1.0
  O  O28  1  0.091  0.953  0.945  1.0
[/CIF]
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The crystal structure described by Cr8O21 crystallizes in the triclinic P-1 space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 5-coordinate geometry to one O(10), one O(3), one O(8), and two equivalent O(5) atoms. In the second Cr site, Cr(2) is bonded in a 8-coordinate geometry to one O(11), one O(2), one O(6), one O(7), two equivalent O(1), and two equivalent O(4) atoms. In the third Cr site, Cr(3) is bonded in a 4-coordinate geometry to one O(3), one O(6), one O(7), and one O(9) atom. In the fourth Cr site, Cr(4) is bonded in a 3-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(11) atoms. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Cr(4) and two equivalent Cr(2) atoms. In the second O site, O(2) is bonded in an L-shaped geometry to one Cr(2) and one Cr(4) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Cr(1) and one Cr(3) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Cr(4) and two equivalent Cr(2) atoms. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Cr(1) atoms. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Cr(2) and one Cr(3) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Cr(2) and one Cr(3) atom. In the eighth O site, O(8) is bonded in a single-bond geometry to one Cr(1) atom. In the ninth O site, O(9) is bonded in a single-bond geometry to one Cr(3) atom. In the tenth O site, O(10) is bonded in a linear geometry to two equivalent Cr(1) atoms. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Cr(2) and two equivalent Cr(4) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Cr8O21
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.458
_cell_length_b   6.748
_cell_length_c   12.889
_cell_angle_alpha   105.035
_cell_angle_beta   87.482
_cell_angle_gamma   102.918
_symmetry_Int_Tables_number   1
_cell_volume   446.872
_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
  Cr  Cr0  1  0.735  0.678  0.528  1.0
  Cr  Cr1  1  0.859  0.712  0.074  1.0
  Cr  Cr2  1  0.653  0.613  0.749  1.0
  Cr  Cr3  1  0.300  0.862  0.904  1.0
  Cr  Cr4  1  0.700  0.138  0.096  1.0
  Cr  Cr5  1  0.141  0.288  0.926  1.0
  Cr  Cr6  1  0.347  0.387  0.251  1.0
  Cr  Cr7  1  0.265  0.322  0.472  1.0
  O  O8  1  0.909  0.047  0.055  1.0
  O  O9  1  0.634  0.912  0.220  1.0
  O  O10  1  0.375  0.297  0.382  1.0
  O  O11  1  0.832  0.412  0.077  1.0
  O  O12  1  0.023  0.459  0.422  1.0
  O  O13  1  0.369  0.486  0.803  1.0
  O  O14  1  0.847  0.398  0.826  1.0
  O  O15  1  0.189  0.037  0.581  1.0
  O  O16  1  0.153  0.602  0.174  1.0
  O  O17  1  0.761  0.864  0.741  1.0
  O  O18  1  0.625  0.703  0.618  1.0
  O  O19  1  0.500  0.500  0.500  1.0
  O  O20  1  0.437  0.181  0.023  1.0
  O  O21  1  0.631  0.514  0.197  1.0
  O  O22  1  0.811  0.963  0.419  1.0
  O  O23  1  0.239  0.136  0.259  1.0
  O  O24  1  0.168  0.588  0.923  1.0
  O  O25  1  0.977  0.541  0.578  1.0
  O  O26  1  0.366  0.088  0.780  1.0
  O  O27  1  0.563  0.819  0.977  1.0
  O  O28  1  0.091  0.953  0.945  1.0
[/CIF]
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