The compound described by Na2Cr2O5 crystallizes in the orthorhombic Ima2 space group. Na(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(2), and four equivalent O(1) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CrO6 octahedra that share corners with four equivalent Cr(1)O6 octahedra and corners with two equivalent Cr(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the second Cr site, Cr(2) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form CrO4 tetrahedra that share corners with two equivalent Cr(1)O6 octahedra and corners with two equivalent Cr(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Na(1) and two equivalent Cr(1) atoms to form distorted ONa4Cr2 octahedra that share corners with two equivalent O(1)Na4Cr2 octahedra, corners with four equivalent O(3)Na2Cr2 tetrahedra, edges with two equivalent O(1)Na4Cr2 octahedra, and faces with four equivalent O(1)Na4Cr2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Cr(1), and one Cr(2) atom. In the third O site, O(3) is bonded to two equivalent Na(1) and two equivalent Cr(2) atoms to form distorted ONa2Cr2 tetrahedra that share corners with eight equivalent O(1)Na4Cr2 octahedra and corners with two equivalent O(3)Na2Cr2 tetrahedra. The corner-sharing octahedral tilt angles range from 19-87°. is represented by the CIF file [CIF]
data_Na2Cr2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.048
_cell_length_b   8.048
_cell_length_c   8.048
_cell_angle_alpha   140.955
_cell_angle_beta   139.501
_cell_angle_gamma   57.516
_symmetry_Int_Tables_number   1
_cell_volume   211.448
_cell_formula_units_Z   2
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
  Na  Na0  1  0.926  0.394  0.531  1.0
  Na  Na1  1  0.074  0.604  0.468  1.0
  Na  Na2  1  0.363  0.894  0.468  1.0
  Na  Na3  1  0.637  0.104  0.531  1.0
  Cr  Cr4  1  0.000  0.011  0.011  1.0
  Cr  Cr5  1  0.500  0.511  0.011  1.0
  Cr  Cr6  1  0.672  0.704  0.876  1.0
  Cr  Cr7  1  0.328  0.204  0.031  1.0
  O  O8  1  0.270  0.278  0.515  1.0
  O  O9  1  0.730  0.245  0.008  1.0
  O  O10  1  0.264  0.778  0.008  1.0
  O  O11  1  0.736  0.745  0.515  1.0
  O  O12  1  0.924  0.887  0.100  1.0
  O  O13  1  0.076  0.176  0.963  1.0
  O  O14  1  0.287  0.387  0.963  1.0
  O  O15  1  0.713  0.676  0.100  1.0
  O  O16  1  0.617  0.365  0.482  1.0
  O  O17  1  0.383  0.865  0.748  1.0
[/CIF]
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The compound described by Na2Cr2O5 crystallizes in the orthorhombic Ima2 space group. Na(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(2), and four equivalent O(1) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CrO6 octahedra that share corners with four equivalent Cr(1)O6 octahedra and corners with two equivalent Cr(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the second Cr site, Cr(2) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form CrO4 tetrahedra that share corners with two equivalent Cr(1)O6 octahedra and corners with two equivalent Cr(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Na(1) and two equivalent Cr(1) atoms to form distorted ONa4Cr2 octahedra that share corners with two equivalent O(1)Na4Cr2 octahedra, corners with four equivalent O(3)Na2Cr2 tetrahedra, edges with two equivalent O(1)Na4Cr2 octahedra, and faces with four equivalent O(1)Na4Cr2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Cr(1), and one Cr(2) atom. In the third O site, O(3) is bonded to two equivalent Na(1) and two equivalent Cr(2) atoms to form distorted ONa2Cr2 tetrahedra that share corners with eight equivalent O(1)Na4Cr2 octahedra and corners with two equivalent O(3)Na2Cr2 tetrahedra. The corner-sharing octahedral tilt angles range from 19-87°. is represented by the CIF file [CIF]
data_Na2Cr2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.048
_cell_length_b   8.048
_cell_length_c   8.048
_cell_angle_alpha   140.955
_cell_angle_beta   139.501
_cell_angle_gamma   57.516
_symmetry_Int_Tables_number   1
_cell_volume   211.448
_cell_formula_units_Z   2
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
  Na  Na0  1  0.926  0.394  0.531  1.0
  Na  Na1  1  0.074  0.604  0.468  1.0
  Na  Na2  1  0.363  0.894  0.468  1.0
  Na  Na3  1  0.637  0.104  0.531  1.0
  Cr  Cr4  1  0.000  0.011  0.011  1.0
  Cr  Cr5  1  0.500  0.511  0.011  1.0
  Cr  Cr6  1  0.672  0.704  0.876  1.0
  Cr  Cr7  1  0.328  0.204  0.031  1.0
  O  O8  1  0.270  0.278  0.515  1.0
  O  O9  1  0.730  0.245  0.008  1.0
  O  O10  1  0.264  0.778  0.008  1.0
  O  O11  1  0.736  0.745  0.515  1.0
  O  O12  1  0.924  0.887  0.100  1.0
  O  O13  1  0.076  0.176  0.963  1.0
  O  O14  1  0.287  0.387  0.963  1.0
  O  O15  1  0.713  0.676  0.100  1.0
  O  O16  1  0.617  0.365  0.482  1.0
  O  O17  1  0.383  0.865  0.748  1.0
[/CIF]
.