The crystal structure described by Na6P2H2O9 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(2), and two equivalent O(5) atoms. In the second Na site, Na(2) is bonded in a 7-coordinate geometry to one H(1), one O(1), one O(3), two equivalent O(2), and two equivalent O(5) atoms. In the third Na site, Na(3) is bonded to one O(1), one O(5), two equivalent O(3), and two equivalent O(4) atoms to form distorted NaO6 octahedra that share corners with two equivalent Na(3)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra,  an edgeedge with one P(1)O4 tetrahedra, and  a faceface with one Na(3)O6 octahedra. The corner-sharing octahedral tilt angles are 78°. P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with three equivalent Na(3)O6 octahedra and  an edgeedge with one Na(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-69°. H(1) is bonded in a single-bond geometry to one Na(2) and one O(1) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded in a water-like geometry to two equivalent Na(2), two equivalent Na(3), and two equivalent H(1) atoms. In the second O site, O(2) is bonded to two equivalent Na(1), two equivalent Na(2), and one P(1) atom to form distorted edge-sharing ONa4P square pyramids. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), two equivalent Na(3), and one P(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one Na(1), two equivalent Na(3), and one P(1) atom. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Na(3), two equivalent Na(1), two equivalent Na(2), and one P(1) atom. is represented by the CIF card [CIF]
data_Na6P2H2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.584
_cell_length_b   5.584
_cell_length_c   17.150
_cell_angle_alpha   78.950
_cell_angle_beta   78.950
_cell_angle_gamma   58.771
_symmetry_Int_Tables_number   1
_cell_volume   446.007
_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  0.348  0.289  0.952  1.0
  Na  Na1  1  0.711  0.652  0.548  1.0
  Na  Na2  1  0.652  0.711  0.048  1.0
  Na  Na3  1  0.289  0.348  0.452  1.0
  Na  Na4  1  0.097  0.902  0.597  1.0
  Na  Na5  1  0.098  0.903  0.903  1.0
  Na  Na6  1  0.903  0.098  0.403  1.0
  Na  Na7  1  0.902  0.097  0.097  1.0
  Na  Na8  1  0.517  0.182  0.785  1.0
  Na  Na9  1  0.818  0.483  0.715  1.0
  Na  Na10  1  0.483  0.818  0.215  1.0
  Na  Na11  1  0.182  0.517  0.285  1.0
  P  P12  1  0.230  0.456  0.113  1.0
  P  P13  1  0.544  0.770  0.387  1.0
  P  P14  1  0.770  0.544  0.887  1.0
  P  P15  1  0.456  0.230  0.613  1.0
  H  H16  1  0.934  0.230  0.227  1.0
  H  H17  1  0.770  0.066  0.273  1.0
  H  H18  1  0.066  0.770  0.773  1.0
  H  H19  1  0.230  0.934  0.727  1.0
  O  O20  1  0.959  0.041  0.250  1.0
  O  O21  1  0.041  0.959  0.750  1.0
  O  O22  1  0.132  0.664  0.036  1.0
  O  O23  1  0.336  0.868  0.464  1.0
  O  O24  1  0.868  0.336  0.964  1.0
  O  O25  1  0.664  0.132  0.536  1.0
  O  O26  1  0.493  0.442  0.649  1.0
  O  O27  1  0.558  0.507  0.851  1.0
  O  O28  1  0.507  0.558  0.351  1.0
  O  O29  1  0.442  0.493  0.149  1.0
  O  O30  1  0.521  0.963  0.675  1.0
  O  O31  1  0.037  0.479  0.825  1.0
  O  O32  1  0.479  0.037  0.325  1.0
  O  O33  1  0.963  0.521  0.175  1.0
  O  O34  1  0.372  0.145  0.093  1.0
  O  O35  1  0.855  0.628  0.407  1.0
  O  O36  1  0.628  0.855  0.907  1.0
  O  O37  1  0.145  0.372  0.593  1.0
[/CIF]
.
The crystal structure described by Na6P2H2O9 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(2), and two equivalent O(5) atoms. In the second Na site, Na(2) is bonded in a 7-coordinate geometry to one H(1), one O(1), one O(3), two equivalent O(2), and two equivalent O(5) atoms. In the third Na site, Na(3) is bonded to one O(1), one O(5), two equivalent O(3), and two equivalent O(4) atoms to form distorted NaO6 octahedra that share corners with two equivalent Na(3)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra,  an edgeedge with one P(1)O4 tetrahedra, and  a faceface with one Na(3)O6 octahedra. The corner-sharing octahedral tilt angles are 78°. P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with three equivalent Na(3)O6 octahedra and  an edgeedge with one Na(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-69°. H(1) is bonded in a single-bond geometry to one Na(2) and one O(1) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded in a water-like geometry to two equivalent Na(2), two equivalent Na(3), and two equivalent H(1) atoms. In the second O site, O(2) is bonded to two equivalent Na(1), two equivalent Na(2), and one P(1) atom to form distorted edge-sharing ONa4P square pyramids. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), two equivalent Na(3), and one P(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one Na(1), two equivalent Na(3), and one P(1) atom. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Na(3), two equivalent Na(1), two equivalent Na(2), and one P(1) atom. is represented by the CIF card [CIF]
data_Na6P2H2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.584
_cell_length_b   5.584
_cell_length_c   17.150
_cell_angle_alpha   78.950
_cell_angle_beta   78.950
_cell_angle_gamma   58.771
_symmetry_Int_Tables_number   1
_cell_volume   446.007
_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  0.348  0.289  0.952  1.0
  Na  Na1  1  0.711  0.652  0.548  1.0
  Na  Na2  1  0.652  0.711  0.048  1.0
  Na  Na3  1  0.289  0.348  0.452  1.0
  Na  Na4  1  0.097  0.902  0.597  1.0
  Na  Na5  1  0.098  0.903  0.903  1.0
  Na  Na6  1  0.903  0.098  0.403  1.0
  Na  Na7  1  0.902  0.097  0.097  1.0
  Na  Na8  1  0.517  0.182  0.785  1.0
  Na  Na9  1  0.818  0.483  0.715  1.0
  Na  Na10  1  0.483  0.818  0.215  1.0
  Na  Na11  1  0.182  0.517  0.285  1.0
  P  P12  1  0.230  0.456  0.113  1.0
  P  P13  1  0.544  0.770  0.387  1.0
  P  P14  1  0.770  0.544  0.887  1.0
  P  P15  1  0.456  0.230  0.613  1.0
  H  H16  1  0.934  0.230  0.227  1.0
  H  H17  1  0.770  0.066  0.273  1.0
  H  H18  1  0.066  0.770  0.773  1.0
  H  H19  1  0.230  0.934  0.727  1.0
  O  O20  1  0.959  0.041  0.250  1.0
  O  O21  1  0.041  0.959  0.750  1.0
  O  O22  1  0.132  0.664  0.036  1.0
  O  O23  1  0.336  0.868  0.464  1.0
  O  O24  1  0.868  0.336  0.964  1.0
  O  O25  1  0.664  0.132  0.536  1.0
  O  O26  1  0.493  0.442  0.649  1.0
  O  O27  1  0.558  0.507  0.851  1.0
  O  O28  1  0.507  0.558  0.351  1.0
  O  O29  1  0.442  0.493  0.149  1.0
  O  O30  1  0.521  0.963  0.675  1.0
  O  O31  1  0.037  0.479  0.825  1.0
  O  O32  1  0.479  0.037  0.325  1.0
  O  O33  1  0.963  0.521  0.175  1.0
  O  O34  1  0.372  0.145  0.093  1.0
  O  O35  1  0.855  0.628  0.407  1.0
  O  O36  1  0.628  0.855  0.907  1.0
  O  O37  1  0.145  0.372  0.593  1.0
[/CIF]
.