The compound described by Na2SeO9 crystallizes in the tetragonal P4_322 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. In the second Na site, Na(2) is bonded in a see-saw-like geometry to two equivalent O(3) and two equivalent O(4) atoms. Se(1) is bonded in a water-like geometry to two equivalent O(2) and two equivalent O(3) atoms. There are five inequivalent O sites. In the first O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one O(1) atom. In the second O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Na(1) and one O(2) atom. In the third O site, O(1) is bonded in a rectangular see-saw-like geometry to two equivalent Na(1) and two equivalent O(4) atoms. In the fourth O site, O(2) is bonded in a distorted water-like geometry to one Se(1) and one O(5) atom. In the fifth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Na(2), and one Se(1) atom. is represented by the CIF card [CIF]
data_Na2SeO9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.719
_cell_length_b   7.719
_cell_length_c   13.587
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   809.675
_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
  Na  Na0  1  0.614  0.500  0.750  1.0
  Na  Na1  1  0.386  0.500  0.250  1.0
  Na  Na2  1  0.500  0.614  0.500  1.0
  Na  Na3  1  0.500  0.386  0.000  1.0
  Na  Na4  1  0.000  0.590  0.000  1.0
  Na  Na5  1  0.000  0.410  0.500  1.0
  Na  Na6  1  0.410  0.000  0.750  1.0
  Na  Na7  1  0.590  0.000  0.250  1.0
  Se  Se8  1  0.993  0.500  0.250  1.0
  Se  Se9  1  0.007  0.500  0.750  1.0
  Se  Se10  1  0.500  0.993  0.000  1.0
  Se  Se11  1  0.500  0.007  0.500  1.0
  O  O12  1  0.400  0.400  0.625  1.0
  O  O13  1  0.600  0.600  0.125  1.0
  O  O14  1  0.600  0.400  0.375  1.0
  O  O15  1  0.400  0.600  0.875  1.0
  O  O16  1  0.040  0.825  0.213  1.0
  O  O17  1  0.960  0.175  0.713  1.0
  O  O18  1  0.175  0.040  0.963  1.0
  O  O19  1  0.825  0.960  0.463  1.0
  O  O20  1  0.960  0.825  0.787  1.0
  O  O21  1  0.040  0.175  0.287  1.0
  O  O22  1  0.825  0.040  0.037  1.0
  O  O23  1  0.175  0.960  0.537  1.0
  O  O24  1  0.875  0.520  0.652  1.0
  O  O25  1  0.125  0.480  0.152  1.0
  O  O26  1  0.480  0.875  0.402  1.0
  O  O27  1  0.520  0.125  0.902  1.0
  O  O28  1  0.125  0.520  0.348  1.0
  O  O29  1  0.875  0.480  0.848  1.0
  O  O30  1  0.520  0.875  0.598  1.0
  O  O31  1  0.480  0.125  0.098  1.0
  O  O32  1  0.702  0.629  0.044  1.0
  O  O33  1  0.298  0.371  0.544  1.0
  O  O34  1  0.371  0.702  0.794  1.0
  O  O35  1  0.629  0.298  0.294  1.0
  O  O36  1  0.298  0.629  0.956  1.0
  O  O37  1  0.702  0.371  0.456  1.0
  O  O38  1  0.629  0.702  0.206  1.0
  O  O39  1  0.371  0.298  0.706  1.0
  O  O40  1  0.828  0.798  0.453  1.0
  O  O41  1  0.172  0.202  0.953  1.0
  O  O42  1  0.202  0.828  0.203  1.0
  O  O43  1  0.798  0.172  0.703  1.0
  O  O44  1  0.172  0.798  0.547  1.0
  O  O45  1  0.828  0.202  0.047  1.0
  O  O46  1  0.798  0.828  0.797  1.0
  O  O47  1  0.202  0.172  0.297  1.0
[/CIF]
.
The compound described by Na2SeO9 crystallizes in the tetragonal P4_322 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. In the second Na site, Na(2) is bonded in a see-saw-like geometry to two equivalent O(3) and two equivalent O(4) atoms. Se(1) is bonded in a water-like geometry to two equivalent O(2) and two equivalent O(3) atoms. There are five inequivalent O sites. In the first O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one O(1) atom. In the second O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Na(1) and one O(2) atom. In the third O site, O(1) is bonded in a rectangular see-saw-like geometry to two equivalent Na(1) and two equivalent O(4) atoms. In the fourth O site, O(2) is bonded in a distorted water-like geometry to one Se(1) and one O(5) atom. In the fifth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Na(2), and one Se(1) atom. is represented by the CIF card [CIF]
data_Na2SeO9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.719
_cell_length_b   7.719
_cell_length_c   13.587
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   809.675
_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
  Na  Na0  1  0.614  0.500  0.750  1.0
  Na  Na1  1  0.386  0.500  0.250  1.0
  Na  Na2  1  0.500  0.614  0.500  1.0
  Na  Na3  1  0.500  0.386  0.000  1.0
  Na  Na4  1  0.000  0.590  0.000  1.0
  Na  Na5  1  0.000  0.410  0.500  1.0
  Na  Na6  1  0.410  0.000  0.750  1.0
  Na  Na7  1  0.590  0.000  0.250  1.0
  Se  Se8  1  0.993  0.500  0.250  1.0
  Se  Se9  1  0.007  0.500  0.750  1.0
  Se  Se10  1  0.500  0.993  0.000  1.0
  Se  Se11  1  0.500  0.007  0.500  1.0
  O  O12  1  0.400  0.400  0.625  1.0
  O  O13  1  0.600  0.600  0.125  1.0
  O  O14  1  0.600  0.400  0.375  1.0
  O  O15  1  0.400  0.600  0.875  1.0
  O  O16  1  0.040  0.825  0.213  1.0
  O  O17  1  0.960  0.175  0.713  1.0
  O  O18  1  0.175  0.040  0.963  1.0
  O  O19  1  0.825  0.960  0.463  1.0
  O  O20  1  0.960  0.825  0.787  1.0
  O  O21  1  0.040  0.175  0.287  1.0
  O  O22  1  0.825  0.040  0.037  1.0
  O  O23  1  0.175  0.960  0.537  1.0
  O  O24  1  0.875  0.520  0.652  1.0
  O  O25  1  0.125  0.480  0.152  1.0
  O  O26  1  0.480  0.875  0.402  1.0
  O  O27  1  0.520  0.125  0.902  1.0
  O  O28  1  0.125  0.520  0.348  1.0
  O  O29  1  0.875  0.480  0.848  1.0
  O  O30  1  0.520  0.875  0.598  1.0
  O  O31  1  0.480  0.125  0.098  1.0
  O  O32  1  0.702  0.629  0.044  1.0
  O  O33  1  0.298  0.371  0.544  1.0
  O  O34  1  0.371  0.702  0.794  1.0
  O  O35  1  0.629  0.298  0.294  1.0
  O  O36  1  0.298  0.629  0.956  1.0
  O  O37  1  0.702  0.371  0.456  1.0
  O  O38  1  0.629  0.702  0.206  1.0
  O  O39  1  0.371  0.298  0.706  1.0
  O  O40  1  0.828  0.798  0.453  1.0
  O  O41  1  0.172  0.202  0.953  1.0
  O  O42  1  0.202  0.828  0.203  1.0
  O  O43  1  0.798  0.172  0.703  1.0
  O  O44  1  0.172  0.798  0.547  1.0
  O  O45  1  0.828  0.202  0.047  1.0
  O  O46  1  0.798  0.828  0.797  1.0
  O  O47  1  0.202  0.172  0.297  1.0
[/CIF]
.