The compound described by Na5H7(Se2O9)2 crystallizes in the triclinic P1 space group. There are five inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(13), one O(18), and one O(9) atom to form distorted NaO4 trigonal pyramids that share  a cornercorner with one Se(4)O4 tetrahedra. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(10), one O(14), one O(17), one O(3), and one O(6) atom. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one H(2), one H(5), one H(6), one O(12), one O(13), one O(14), and one O(9) atom. In the fourth Na site, Na(4) is bonded in a 6-coordinate geometry to one H(7), one O(12), one O(4), one O(5), one O(6), and one O(8) atom. In the fifth Na site, Na(5) is bonded in a 5-coordinate geometry to one O(11), one O(2), one O(3), one O(5), and one O(7) atom. There are seven inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one H(6) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one Na(3) and one H(5) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(7) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(10) atom. In the fifth H site, H(5) is bonded in a distorted L-shaped geometry to one Na(3) and one H(2) atom. In the sixth H site, H(6) is bonded in a distorted water-like geometry to one Na(3) and one H(1) atom. In the seventh H site, H(7) is bonded in a distorted linear geometry to one Na(4), one O(5), and one O(8) atom. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a water-like geometry to one O(5) and one O(9) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(10), one O(2), and one O(6) atom. In the third Se site, Se(3) is bonded in a tetrahedral geometry to one O(11), one O(15), one O(17), and one O(3) atom. In the fourth Se site, Se(4) is bonded to one O(12), one O(16), one O(18), and one O(4) atom to form SeO4 tetrahedra that share  a cornercorner with one Na(1)O4 trigonal pyramid. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one O(7), and one O(8) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Na(5) and one Se(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one Na(5), and one Se(3) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Na(4) and one Se(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(4), one Na(5), one H(7), and one Se(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(2), one Na(4), and one Se(2) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Na(5), one H(3), and one O(1) atom. In the eighth O site, O(8) is bonded in a single-bond geometry to one Na(4), one H(7), and one O(1) atom. In the ninth O site, O(9) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Na(3), and one Se(1) atom. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one Na(2), one H(4), and one Se(2) atom. In the eleventh O site, O(11) is bonded in a bent 120 degrees geometry to one Na(5) and one Se(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Na(3), one Na(4), and one Se(4) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(3), and one O(15) atom. In the fourteenth O site, O(14) is bonded in a trigonal planar geometry to one Na(2), one Na(3), and one O(16) atom. In the fifteenth O site, O(15) is bonded in a distorted bent 120 degrees geometry to one Se(3) and one O(13) atom. In the sixteenth O site, O(16) is bonded in a distorted bent 120 degrees geometry to one Se(4) and one O(14) atom. In the seventeenth O site, O(17) is bonded in a distorted bent 150 degrees geometry to one Na(2) and one Se(3) atom. In the eighteenth O site, O(18) is bonded in a bent 150 degrees geometry to one Na(1) and one Se(4) atom. is represented by the CIF file [CIF]
data_Na5H7(Se2O9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.249
_cell_length_b   7.497
_cell_length_c   11.208
_cell_angle_alpha   98.312
_cell_angle_beta   96.406
_cell_angle_gamma   97.659
_symmetry_Int_Tables_number   1
_cell_volume   510.357
_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  0.978  0.235  0.280  1.0
  Na  Na1  1  0.141  0.745  0.738  1.0
  Na  Na2  1  0.490  0.026  0.462  1.0
  Na  Na3  1  0.406  0.800  0.107  1.0
  Na  Na4  1  0.599  0.154  0.881  1.0
  H  H5  1  0.450  0.628  0.408  1.0
  H  H6  1  0.565  0.359  0.562  1.0
  H  H7  1  0.067  0.306  0.027  1.0
  H  H8  1  0.889  0.805  0.896  1.0
  H  H9  1  0.657  0.322  0.595  1.0
  H  H10  1  0.370  0.683  0.383  1.0
  H  H11  1  0.265  0.036  0.026  1.0
  Se  Se12  1  0.452  0.334  0.178  1.0
  Se  Se13  1  0.562  0.594  0.833  1.0
  Se  Se14  1  0.064  0.193  0.713  1.0
  Se  Se15  1  0.934  0.764  0.295  1.0
  O  O16  1  0.986  0.070  0.075  1.0
  O  O17  1  0.629  0.477  0.945  1.0
  O  O18  1  0.253  0.076  0.764  1.0
  O  O19  1  0.720  0.859  0.249  1.0
  O  O20  1  0.467  0.136  0.078  1.0
  O  O21  1  0.434  0.764  0.897  1.0
  O  O22  1  0.931  0.217  0.010  1.0
  O  O23  1  0.105  0.957  0.003  1.0
  O  O24  1  0.371  0.270  0.307  1.0
  O  O25  1  0.822  0.732  0.817  1.0
  O  O26  1  0.808  0.096  0.708  1.0
  O  O27  1  0.172  0.880  0.277  1.0
  O  O28  1  0.903  0.142  0.463  1.0
  O  O29  1  0.142  0.835  0.537  1.0
  O  O30  1  0.095  0.190  0.536  1.0
  O  O31  1  0.939  0.794  0.476  1.0
  O  O32  1  0.114  0.409  0.780  1.0
  O  O33  1  0.912  0.543  0.241  1.0
[/CIF]
.
The compound described by Na5H7(Se2O9)2 crystallizes in the triclinic P1 space group. There are five inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(13), one O(18), and one O(9) atom to form distorted NaO4 trigonal pyramids that share  a cornercorner with one Se(4)O4 tetrahedra. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(10), one O(14), one O(17), one O(3), and one O(6) atom. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one H(2), one H(5), one H(6), one O(12), one O(13), one O(14), and one O(9) atom. In the fourth Na site, Na(4) is bonded in a 6-coordinate geometry to one H(7), one O(12), one O(4), one O(5), one O(6), and one O(8) atom. In the fifth Na site, Na(5) is bonded in a 5-coordinate geometry to one O(11), one O(2), one O(3), one O(5), and one O(7) atom. There are seven inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one H(6) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one Na(3) and one H(5) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(7) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(10) atom. In the fifth H site, H(5) is bonded in a distorted L-shaped geometry to one Na(3) and one H(2) atom. In the sixth H site, H(6) is bonded in a distorted water-like geometry to one Na(3) and one H(1) atom. In the seventh H site, H(7) is bonded in a distorted linear geometry to one Na(4), one O(5), and one O(8) atom. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a water-like geometry to one O(5) and one O(9) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(10), one O(2), and one O(6) atom. In the third Se site, Se(3) is bonded in a tetrahedral geometry to one O(11), one O(15), one O(17), and one O(3) atom. In the fourth Se site, Se(4) is bonded to one O(12), one O(16), one O(18), and one O(4) atom to form SeO4 tetrahedra that share  a cornercorner with one Na(1)O4 trigonal pyramid. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one O(7), and one O(8) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Na(5) and one Se(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one Na(5), and one Se(3) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Na(4) and one Se(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(4), one Na(5), one H(7), and one Se(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(2), one Na(4), and one Se(2) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Na(5), one H(3), and one O(1) atom. In the eighth O site, O(8) is bonded in a single-bond geometry to one Na(4), one H(7), and one O(1) atom. In the ninth O site, O(9) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Na(3), and one Se(1) atom. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one Na(2), one H(4), and one Se(2) atom. In the eleventh O site, O(11) is bonded in a bent 120 degrees geometry to one Na(5) and one Se(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Na(3), one Na(4), and one Se(4) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(3), and one O(15) atom. In the fourteenth O site, O(14) is bonded in a trigonal planar geometry to one Na(2), one Na(3), and one O(16) atom. In the fifteenth O site, O(15) is bonded in a distorted bent 120 degrees geometry to one Se(3) and one O(13) atom. In the sixteenth O site, O(16) is bonded in a distorted bent 120 degrees geometry to one Se(4) and one O(14) atom. In the seventeenth O site, O(17) is bonded in a distorted bent 150 degrees geometry to one Na(2) and one Se(3) atom. In the eighteenth O site, O(18) is bonded in a bent 150 degrees geometry to one Na(1) and one Se(4) atom. is represented by the CIF file [CIF]
data_Na5H7(Se2O9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.249
_cell_length_b   7.497
_cell_length_c   11.208
_cell_angle_alpha   98.312
_cell_angle_beta   96.406
_cell_angle_gamma   97.659
_symmetry_Int_Tables_number   1
_cell_volume   510.357
_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  0.978  0.235  0.280  1.0
  Na  Na1  1  0.141  0.745  0.738  1.0
  Na  Na2  1  0.490  0.026  0.462  1.0
  Na  Na3  1  0.406  0.800  0.107  1.0
  Na  Na4  1  0.599  0.154  0.881  1.0
  H  H5  1  0.450  0.628  0.408  1.0
  H  H6  1  0.565  0.359  0.562  1.0
  H  H7  1  0.067  0.306  0.027  1.0
  H  H8  1  0.889  0.805  0.896  1.0
  H  H9  1  0.657  0.322  0.595  1.0
  H  H10  1  0.370  0.683  0.383  1.0
  H  H11  1  0.265  0.036  0.026  1.0
  Se  Se12  1  0.452  0.334  0.178  1.0
  Se  Se13  1  0.562  0.594  0.833  1.0
  Se  Se14  1  0.064  0.193  0.713  1.0
  Se  Se15  1  0.934  0.764  0.295  1.0
  O  O16  1  0.986  0.070  0.075  1.0
  O  O17  1  0.629  0.477  0.945  1.0
  O  O18  1  0.253  0.076  0.764  1.0
  O  O19  1  0.720  0.859  0.249  1.0
  O  O20  1  0.467  0.136  0.078  1.0
  O  O21  1  0.434  0.764  0.897  1.0
  O  O22  1  0.931  0.217  0.010  1.0
  O  O23  1  0.105  0.957  0.003  1.0
  O  O24  1  0.371  0.270  0.307  1.0
  O  O25  1  0.822  0.732  0.817  1.0
  O  O26  1  0.808  0.096  0.708  1.0
  O  O27  1  0.172  0.880  0.277  1.0
  O  O28  1  0.903  0.142  0.463  1.0
  O  O29  1  0.142  0.835  0.537  1.0
  O  O30  1  0.095  0.190  0.536  1.0
  O  O31  1  0.939  0.794  0.476  1.0
  O  O32  1  0.114  0.409  0.780  1.0
  O  O33  1  0.912  0.543  0.241  1.0
[/CIF]
.