The material structure described by Na5H7(Se2O9)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(6), two equivalent O(8), and two equivalent O(9) atoms to form distorted NaO6 octahedra that share corners with four equivalent Se(2)O4 tetrahedra and edges with two equivalent Na(2)O6 octahedra. In the second Na site, Na(2) is bonded to one O(1), one O(3), one O(6), one O(8), and two equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent Se(2)O4 tetrahedra, corners with four equivalent Se(1)O4 tetrahedra,  an edgeedge with one Na(1)O6 octahedra, and  an edgeedge with one Na(2)O6 octahedra. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(4), one O(5), one O(6), one O(7), and one O(9) atom. There are four inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to two equivalent O(1) atoms. In the second H site, H(2) is bonded in a distorted linear geometry to one O(3) and one O(5) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(4) and one O(9) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(9) atom. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SeO4 tetrahedra that share corners with four equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-59°. In the second Se site, Se(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SeO4 tetrahedra that share corners with two equivalent Na(1)O6 octahedra and corners with two equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-74°. There are nine inequivalent O sites. In the first O site, O(9) is bonded in a distorted water-like geometry to one Na(1), one Na(3), one H(3), and one H(4) atom. In the second O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), one Na(3), one H(1), and one Se(1) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to one Na(3), two equivalent Na(2), and one Se(1) atom. In the fourth O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one H(2), and one Se(1) atom. In the fifth O site, O(4) is bonded in a 3-coordinate geometry to one Na(3), one H(3), and one Se(1) atom. In the sixth O site, O(5) is bonded in a 3-coordinate geometry to one Na(3), one H(2), and one Se(2) atom. In the seventh O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Na(3), and one Se(2) atom. In the eighth O site, O(7) is bonded in a bent 150 degrees geometry to one Na(3) and one Se(2) atom. In the ninth O site, O(8) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), and one Se(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na5H7(Se2O9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.121
_cell_length_b   7.379
_cell_length_c   10.099
_cell_angle_alpha   102.191
_cell_angle_beta   99.606
_cell_angle_gamma   100.748
_symmetry_Int_Tables_number   1
_cell_volume   427.820
_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
  Na  Na0  1  0.000  0.000  0.000  1.0
  Na  Na1  1  0.134  0.171  0.396  1.0
  Na  Na2  1  0.866  0.829  0.604  1.0
  Na  Na3  1  0.646  0.744  0.195  1.0
  Na  Na4  1  0.354  0.256  0.805  1.0
  H  H5  1  0.500  0.000  0.500  1.0
  H  H6  1  0.272  0.557  0.619  1.0
  H  H7  1  0.728  0.443  0.381  1.0
  H  H8  1  0.976  0.340  0.904  1.0
  H  H9  1  0.024  0.660  0.096  1.0
  H  H10  1  0.160  0.401  0.045  1.0
  H  H11  1  0.840  0.599  0.955  1.0
  Se  Se12  1  0.246  0.691  0.373  1.0
  Se  Se13  1  0.754  0.309  0.627  1.0
  Se  Se14  1  0.412  0.797  0.824  1.0
  Se  Se15  1  0.588  0.203  0.176  1.0
  O  O16  1  0.513  0.840  0.444  1.0
  O  O17  1  0.487  0.160  0.556  1.0
  O  O18  1  0.054  0.820  0.397  1.0
  O  O19  1  0.946  0.180  0.603  1.0
  O  O20  1  0.223  0.515  0.453  1.0
  O  O21  1  0.777  0.485  0.547  1.0
  O  O22  1  0.250  0.611  0.207  1.0
  O  O23  1  0.750  0.389  0.793  1.0
  O  O24  1  0.303  0.559  0.722  1.0
  O  O25  1  0.697  0.441  0.278  1.0
  O  O26  1  0.222  0.917  0.773  1.0
  O  O27  1  0.778  0.083  0.227  1.0
  O  O28  1  0.415  0.771  0.981  1.0
  O  O29  1  0.585  0.229  0.019  1.0
  O  O30  1  0.667  0.876  0.794  1.0
  O  O31  1  0.333  0.124  0.206  1.0
  O  O32  1  0.108  0.305  0.956  1.0
  O  O33  1  0.892  0.695  0.044  1.0
[/CIF]
.
The material structure described by Na5H7(Se2O9)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(6), two equivalent O(8), and two equivalent O(9) atoms to form distorted NaO6 octahedra that share corners with four equivalent Se(2)O4 tetrahedra and edges with two equivalent Na(2)O6 octahedra. In the second Na site, Na(2) is bonded to one O(1), one O(3), one O(6), one O(8), and two equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent Se(2)O4 tetrahedra, corners with four equivalent Se(1)O4 tetrahedra,  an edgeedge with one Na(1)O6 octahedra, and  an edgeedge with one Na(2)O6 octahedra. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(4), one O(5), one O(6), one O(7), and one O(9) atom. There are four inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to two equivalent O(1) atoms. In the second H site, H(2) is bonded in a distorted linear geometry to one O(3) and one O(5) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(4) and one O(9) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(9) atom. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SeO4 tetrahedra that share corners with four equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-59°. In the second Se site, Se(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SeO4 tetrahedra that share corners with two equivalent Na(1)O6 octahedra and corners with two equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-74°. There are nine inequivalent O sites. In the first O site, O(9) is bonded in a distorted water-like geometry to one Na(1), one Na(3), one H(3), and one H(4) atom. In the second O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), one Na(3), one H(1), and one Se(1) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to one Na(3), two equivalent Na(2), and one Se(1) atom. In the fourth O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one H(2), and one Se(1) atom. In the fifth O site, O(4) is bonded in a 3-coordinate geometry to one Na(3), one H(3), and one Se(1) atom. In the sixth O site, O(5) is bonded in a 3-coordinate geometry to one Na(3), one H(2), and one Se(2) atom. In the seventh O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Na(3), and one Se(2) atom. In the eighth O site, O(7) is bonded in a bent 150 degrees geometry to one Na(3) and one Se(2) atom. In the ninth O site, O(8) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), and one Se(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na5H7(Se2O9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.121
_cell_length_b   7.379
_cell_length_c   10.099
_cell_angle_alpha   102.191
_cell_angle_beta   99.606
_cell_angle_gamma   100.748
_symmetry_Int_Tables_number   1
_cell_volume   427.820
_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
  Na  Na0  1  0.000  0.000  0.000  1.0
  Na  Na1  1  0.134  0.171  0.396  1.0
  Na  Na2  1  0.866  0.829  0.604  1.0
  Na  Na3  1  0.646  0.744  0.195  1.0
  Na  Na4  1  0.354  0.256  0.805  1.0
  H  H5  1  0.500  0.000  0.500  1.0
  H  H6  1  0.272  0.557  0.619  1.0
  H  H7  1  0.728  0.443  0.381  1.0
  H  H8  1  0.976  0.340  0.904  1.0
  H  H9  1  0.024  0.660  0.096  1.0
  H  H10  1  0.160  0.401  0.045  1.0
  H  H11  1  0.840  0.599  0.955  1.0
  Se  Se12  1  0.246  0.691  0.373  1.0
  Se  Se13  1  0.754  0.309  0.627  1.0
  Se  Se14  1  0.412  0.797  0.824  1.0
  Se  Se15  1  0.588  0.203  0.176  1.0
  O  O16  1  0.513  0.840  0.444  1.0
  O  O17  1  0.487  0.160  0.556  1.0
  O  O18  1  0.054  0.820  0.397  1.0
  O  O19  1  0.946  0.180  0.603  1.0
  O  O20  1  0.223  0.515  0.453  1.0
  O  O21  1  0.777  0.485  0.547  1.0
  O  O22  1  0.250  0.611  0.207  1.0
  O  O23  1  0.750  0.389  0.793  1.0
  O  O24  1  0.303  0.559  0.722  1.0
  O  O25  1  0.697  0.441  0.278  1.0
  O  O26  1  0.222  0.917  0.773  1.0
  O  O27  1  0.778  0.083  0.227  1.0
  O  O28  1  0.415  0.771  0.981  1.0
  O  O29  1  0.585  0.229  0.019  1.0
  O  O30  1  0.667  0.876  0.794  1.0
  O  O31  1  0.333  0.124  0.206  1.0
  O  O32  1  0.108  0.305  0.956  1.0
  O  O33  1  0.892  0.695  0.044  1.0
[/CIF]
.