The crystal structure described by Cr9O13 crystallizes in the monoclinic C2/m space group. There are five inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(6) and four equivalent O(7) atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 8°. In the second Cr site, Cr(2) is bonded to one O(4), two equivalent O(1), and three equivalent O(3) atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedra are not tilted. In the third Cr site, Cr(3) is bonded to one O(5), two equivalent O(6), and three equivalent O(7) atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 8°. In the fourth Cr site, Cr(4) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. In the fifth Cr site, Cr(5) is bonded in a 6-coordinate geometry to one O(2), one O(7), two equivalent O(5), and two equivalent O(6) atoms. There are seven inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Cr(4) and four equivalent Cr(2) atoms to form OCr6 octahedra that share corners with four equivalent O(3)Cr5 square pyramids, edges with two equivalent O(1)Cr6 octahedra, and edges with six equivalent O(3)Cr5 square pyramids. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Cr(4) and one Cr(5) atom. In the third O site, O(3) is bonded to two equivalent Cr(4) and three equivalent Cr(2) atoms to form OCr5 square pyramids that share corners with two equivalent O(1)Cr6 octahedra, edges with three equivalent O(1)Cr6 octahedra, and edges with four equivalent O(3)Cr5 square pyramids. The corner-sharing octahedral tilt angles are 6°. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Cr(2) and two equivalent Cr(4) atoms. In the fifth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Cr(3) and two equivalent Cr(5) atoms. In the sixth O site, O(6) is bonded to one Cr(1), two equivalent Cr(3), and two equivalent Cr(5) atoms to form OCr5 square pyramids that share corners with two equivalent O(7)Cr6 octahedra,  a cornercorner with one O(6)Cr5 square pyramid, edges with five equivalent O(7)Cr6 octahedra, and edges with two equivalent O(6)Cr5 square pyramids. The corner-sharing octahedral tilt angles are 10°. In the seventh O site, O(7) is bonded to one Cr(5), two equivalent Cr(1), and three equivalent Cr(3) atoms to form distorted OCr6 octahedra that share corners with two equivalent O(7)Cr6 octahedra, corners with two equivalent O(6)Cr5 square pyramids, edges with five equivalent O(7)Cr6 octahedra, and edges with five equivalent O(6)Cr5 square pyramids. The corner-sharing octahedra are not tilted. is represented by the CIF card [CIF]
data_Cr9O13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.245
_cell_length_b   5.245
_cell_length_c   17.139
_cell_angle_alpha   81.355
_cell_angle_beta   81.355
_cell_angle_gamma   33.446
_symmetry_Int_Tables_number   1
_cell_volume   256.624
_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  0.500  0.500  0.500  1.0
  Cr  Cr1  1  0.355  0.355  0.041  1.0
  Cr  Cr2  1  0.645  0.645  0.959  1.0
  Cr  Cr3  1  0.252  0.252  0.419  1.0
  Cr  Cr4  1  0.748  0.748  0.581  1.0
  Cr  Cr5  1  0.059  0.059  0.131  1.0
  Cr  Cr6  1  0.941  0.941  0.869  1.0
  Cr  Cr7  1  0.007  0.007  0.326  1.0
  Cr  Cr8  1  0.993  0.993  0.674  1.0
  O  O9  1  0.000  0.000  0.000  1.0
  O  O10  1  0.110  0.110  0.229  1.0
  O  O11  1  0.890  0.890  0.771  1.0
  O  O12  1  0.718  0.718  0.067  1.0
  O  O13  1  0.282  0.282  0.933  1.0
  O  O14  1  0.438  0.438  0.135  1.0
  O  O15  1  0.562  0.562  0.865  1.0
  O  O16  1  0.387  0.387  0.325  1.0
  O  O17  1  0.613  0.613  0.675  1.0
  O  O18  1  0.626  0.626  0.392  1.0
  O  O19  1  0.374  0.374  0.608  1.0
  O  O20  1  0.860  0.860  0.464  1.0
  O  O21  1  0.140  0.140  0.536  1.0
[/CIF]
.
The crystal structure described by Cr9O13 crystallizes in the monoclinic C2/m space group. There are five inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(6) and four equivalent O(7) atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 8°. In the second Cr site, Cr(2) is bonded to one O(4), two equivalent O(1), and three equivalent O(3) atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedra are not tilted. In the third Cr site, Cr(3) is bonded to one O(5), two equivalent O(6), and three equivalent O(7) atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 8°. In the fourth Cr site, Cr(4) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. In the fifth Cr site, Cr(5) is bonded in a 6-coordinate geometry to one O(2), one O(7), two equivalent O(5), and two equivalent O(6) atoms. There are seven inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Cr(4) and four equivalent Cr(2) atoms to form OCr6 octahedra that share corners with four equivalent O(3)Cr5 square pyramids, edges with two equivalent O(1)Cr6 octahedra, and edges with six equivalent O(3)Cr5 square pyramids. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Cr(4) and one Cr(5) atom. In the third O site, O(3) is bonded to two equivalent Cr(4) and three equivalent Cr(2) atoms to form OCr5 square pyramids that share corners with two equivalent O(1)Cr6 octahedra, edges with three equivalent O(1)Cr6 octahedra, and edges with four equivalent O(3)Cr5 square pyramids. The corner-sharing octahedral tilt angles are 6°. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Cr(2) and two equivalent Cr(4) atoms. In the fifth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Cr(3) and two equivalent Cr(5) atoms. In the sixth O site, O(6) is bonded to one Cr(1), two equivalent Cr(3), and two equivalent Cr(5) atoms to form OCr5 square pyramids that share corners with two equivalent O(7)Cr6 octahedra,  a cornercorner with one O(6)Cr5 square pyramid, edges with five equivalent O(7)Cr6 octahedra, and edges with two equivalent O(6)Cr5 square pyramids. The corner-sharing octahedral tilt angles are 10°. In the seventh O site, O(7) is bonded to one Cr(5), two equivalent Cr(1), and three equivalent Cr(3) atoms to form distorted OCr6 octahedra that share corners with two equivalent O(7)Cr6 octahedra, corners with two equivalent O(6)Cr5 square pyramids, edges with five equivalent O(7)Cr6 octahedra, and edges with five equivalent O(6)Cr5 square pyramids. The corner-sharing octahedra are not tilted. is represented by the CIF card [CIF]
data_Cr9O13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.245
_cell_length_b   5.245
_cell_length_c   17.139
_cell_angle_alpha   81.355
_cell_angle_beta   81.355
_cell_angle_gamma   33.446
_symmetry_Int_Tables_number   1
_cell_volume   256.624
_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  0.500  0.500  0.500  1.0
  Cr  Cr1  1  0.355  0.355  0.041  1.0
  Cr  Cr2  1  0.645  0.645  0.959  1.0
  Cr  Cr3  1  0.252  0.252  0.419  1.0
  Cr  Cr4  1  0.748  0.748  0.581  1.0
  Cr  Cr5  1  0.059  0.059  0.131  1.0
  Cr  Cr6  1  0.941  0.941  0.869  1.0
  Cr  Cr7  1  0.007  0.007  0.326  1.0
  Cr  Cr8  1  0.993  0.993  0.674  1.0
  O  O9  1  0.000  0.000  0.000  1.0
  O  O10  1  0.110  0.110  0.229  1.0
  O  O11  1  0.890  0.890  0.771  1.0
  O  O12  1  0.718  0.718  0.067  1.0
  O  O13  1  0.282  0.282  0.933  1.0
  O  O14  1  0.438  0.438  0.135  1.0
  O  O15  1  0.562  0.562  0.865  1.0
  O  O16  1  0.387  0.387  0.325  1.0
  O  O17  1  0.613  0.613  0.675  1.0
  O  O18  1  0.626  0.626  0.392  1.0
  O  O19  1  0.374  0.374  0.608  1.0
  O  O20  1  0.860  0.860  0.464  1.0
  O  O21  1  0.140  0.140  0.536  1.0
[/CIF]
.