The compound described by Na4As2O7 crystallizes in the monoclinic C2/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form distorted NaO5 trigonal bipyramids that share corners with five equivalent As(1)O4 tetrahedra and edges with two equivalent Na(1)O5 trigonal bipyramids. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), and two equivalent O(2) atoms. As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share  a cornercorner with one As(1)O4 tetrahedra and corners with five equivalent Na(1)O5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(3) is bonded in a rectangular see-saw-like geometry to one Na(2), two equivalent Na(1), and one As(1) atom. In the second O site, O(4) is bonded in a distorted bent 120 degrees geometry to two equivalent Na(2) and two equivalent As(1) atoms. In the third O site, O(1) is bonded to one Na(2), two equivalent Na(1), and one As(1) atom to form distorted edge-sharing ONa3As trigonal pyramids. In the fourth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Na(2), and one As(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na4As2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.844
_cell_length_b   5.844
_cell_length_c   12.223
_cell_angle_alpha   88.522
_cell_angle_beta   88.522
_cell_angle_gamma   118.701
_symmetry_Int_Tables_number   1
_cell_volume   365.622
_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  0.022  0.666  0.872  1.0
  Na  Na1  1  0.334  0.978  0.628  1.0
  Na  Na2  1  0.978  0.334  0.128  1.0
  Na  Na3  1  0.666  0.022  0.372  1.0
  Na  Na4  1  0.295  0.320  0.404  1.0
  Na  Na5  1  0.680  0.705  0.096  1.0
  Na  Na6  1  0.705  0.680  0.596  1.0
  Na  Na7  1  0.320  0.295  0.904  1.0
  As  As8  1  0.993  0.297  0.638  1.0
  As  As9  1  0.703  0.007  0.862  1.0
  As  As10  1  0.007  0.703  0.362  1.0
  As  As11  1  0.297  0.993  0.138  1.0
  O  O12  1  0.555  0.977  0.186  1.0
  O  O13  1  0.023  0.445  0.314  1.0
  O  O14  1  0.445  0.023  0.814  1.0
  O  O15  1  0.977  0.555  0.686  1.0
  O  O16  1  0.359  0.291  0.093  1.0
  O  O17  1  0.709  0.641  0.407  1.0
  O  O18  1  0.641  0.709  0.907  1.0
  O  O19  1  0.291  0.359  0.593  1.0
  O  O20  1  0.113  0.757  0.054  1.0
  O  O21  1  0.243  0.887  0.446  1.0
  O  O22  1  0.887  0.243  0.946  1.0
  O  O23  1  0.757  0.113  0.554  1.0
  O  O24  1  0.935  0.065  0.750  1.0
  O  O25  1  0.065  0.935  0.250  1.0
[/CIF]
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The compound described by Na4As2O7 crystallizes in the monoclinic C2/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form distorted NaO5 trigonal bipyramids that share corners with five equivalent As(1)O4 tetrahedra and edges with two equivalent Na(1)O5 trigonal bipyramids. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), and two equivalent O(2) atoms. As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share  a cornercorner with one As(1)O4 tetrahedra and corners with five equivalent Na(1)O5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(3) is bonded in a rectangular see-saw-like geometry to one Na(2), two equivalent Na(1), and one As(1) atom. In the second O site, O(4) is bonded in a distorted bent 120 degrees geometry to two equivalent Na(2) and two equivalent As(1) atoms. In the third O site, O(1) is bonded to one Na(2), two equivalent Na(1), and one As(1) atom to form distorted edge-sharing ONa3As trigonal pyramids. In the fourth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Na(2), and one As(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na4As2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.844
_cell_length_b   5.844
_cell_length_c   12.223
_cell_angle_alpha   88.522
_cell_angle_beta   88.522
_cell_angle_gamma   118.701
_symmetry_Int_Tables_number   1
_cell_volume   365.622
_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  0.022  0.666  0.872  1.0
  Na  Na1  1  0.334  0.978  0.628  1.0
  Na  Na2  1  0.978  0.334  0.128  1.0
  Na  Na3  1  0.666  0.022  0.372  1.0
  Na  Na4  1  0.295  0.320  0.404  1.0
  Na  Na5  1  0.680  0.705  0.096  1.0
  Na  Na6  1  0.705  0.680  0.596  1.0
  Na  Na7  1  0.320  0.295  0.904  1.0
  As  As8  1  0.993  0.297  0.638  1.0
  As  As9  1  0.703  0.007  0.862  1.0
  As  As10  1  0.007  0.703  0.362  1.0
  As  As11  1  0.297  0.993  0.138  1.0
  O  O12  1  0.555  0.977  0.186  1.0
  O  O13  1  0.023  0.445  0.314  1.0
  O  O14  1  0.445  0.023  0.814  1.0
  O  O15  1  0.977  0.555  0.686  1.0
  O  O16  1  0.359  0.291  0.093  1.0
  O  O17  1  0.709  0.641  0.407  1.0
  O  O18  1  0.641  0.709  0.907  1.0
  O  O19  1  0.291  0.359  0.593  1.0
  O  O20  1  0.113  0.757  0.054  1.0
  O  O21  1  0.243  0.887  0.446  1.0
  O  O22  1  0.887  0.243  0.946  1.0
  O  O23  1  0.757  0.113  0.554  1.0
  O  O24  1  0.935  0.065  0.750  1.0
  O  O25  1  0.065  0.935  0.250  1.0
[/CIF]
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