The crystal structure described by Na3(FeSe2)2 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent Se(1) and four equivalent Se(3) atoms to form NaSe6 octahedra that share corners with eight equivalent Fe(1)Se4 tetrahedra, edges with two equivalent Fe(1)Se4 tetrahedra, and faces with two equivalent Na(1)Se6 octahedra. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one Se(1), two equivalent Se(2), and two equivalent Se(3) atoms. Fe(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form FeSe4 tetrahedra that share corners with four equivalent Na(1)Se6 octahedra,  an edgeedge with one Na(1)Se6 octahedra, and edges with two equivalent Fe(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 14-63°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and two equivalent Fe(1) atoms. In the second Se site, Se(2) is bonded to four equivalent Na(2) and two equivalent Fe(1) atoms to form distorted edge-sharing SeNa4Fe2 pentagonal pyramids. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and two equivalent Fe(1) atoms. is represented by the CIF file [CIF]
data_Na3(FeSe2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.976
_cell_length_b   10.835
_cell_length_c   11.261
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   851.161
_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  0.075  0.250  0.756  1.0
  Na  Na1  1  0.575  0.250  0.744  1.0
  Na  Na2  1  0.925  0.750  0.244  1.0
  Na  Na3  1  0.425  0.750  0.256  1.0
  Na  Na4  1  0.051  0.419  0.141  1.0
  Na  Na5  1  0.551  0.081  0.359  1.0
  Na  Na6  1  0.949  0.919  0.859  1.0
  Na  Na7  1  0.449  0.581  0.641  1.0
  Na  Na8  1  0.949  0.581  0.859  1.0
  Na  Na9  1  0.449  0.919  0.641  1.0
  Na  Na10  1  0.051  0.081  0.141  1.0
  Na  Na11  1  0.551  0.419  0.359  1.0
  Fe  Fe12  1  0.046  0.373  0.471  1.0
  Fe  Fe13  1  0.546  0.127  0.029  1.0
  Fe  Fe14  1  0.954  0.873  0.529  1.0
  Fe  Fe15  1  0.454  0.627  0.971  1.0
  Fe  Fe16  1  0.954  0.627  0.529  1.0
  Fe  Fe17  1  0.454  0.873  0.971  1.0
  Fe  Fe18  1  0.046  0.127  0.471  1.0
  Fe  Fe19  1  0.546  0.373  0.029  1.0
  Se  Se20  1  0.313  0.250  0.539  1.0
  Se  Se21  1  0.813  0.250  0.961  1.0
  Se  Se22  1  0.687  0.750  0.461  1.0
  Se  Se23  1  0.187  0.750  0.039  1.0
  Se  Se24  1  0.379  0.250  0.171  1.0
  Se  Se25  1  0.879  0.250  0.329  1.0
  Se  Se26  1  0.621  0.750  0.829  1.0
  Se  Se27  1  0.121  0.750  0.671  1.0
  Se  Se28  1  0.172  0.555  0.377  1.0
  Se  Se29  1  0.672  0.945  0.123  1.0
  Se  Se30  1  0.828  0.055  0.623  1.0
  Se  Se31  1  0.328  0.445  0.877  1.0
  Se  Se32  1  0.828  0.445  0.623  1.0
  Se  Se33  1  0.328  0.055  0.877  1.0
  Se  Se34  1  0.172  0.945  0.377  1.0
  Se  Se35  1  0.672  0.555  0.123  1.0
[/CIF]
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The crystal structure described by Na3(FeSe2)2 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent Se(1) and four equivalent Se(3) atoms to form NaSe6 octahedra that share corners with eight equivalent Fe(1)Se4 tetrahedra, edges with two equivalent Fe(1)Se4 tetrahedra, and faces with two equivalent Na(1)Se6 octahedra. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one Se(1), two equivalent Se(2), and two equivalent Se(3) atoms. Fe(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form FeSe4 tetrahedra that share corners with four equivalent Na(1)Se6 octahedra,  an edgeedge with one Na(1)Se6 octahedra, and edges with two equivalent Fe(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 14-63°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and two equivalent Fe(1) atoms. In the second Se site, Se(2) is bonded to four equivalent Na(2) and two equivalent Fe(1) atoms to form distorted edge-sharing SeNa4Fe2 pentagonal pyramids. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and two equivalent Fe(1) atoms. is represented by the CIF file [CIF]
data_Na3(FeSe2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.976
_cell_length_b   10.835
_cell_length_c   11.261
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   851.161
_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  0.075  0.250  0.756  1.0
  Na  Na1  1  0.575  0.250  0.744  1.0
  Na  Na2  1  0.925  0.750  0.244  1.0
  Na  Na3  1  0.425  0.750  0.256  1.0
  Na  Na4  1  0.051  0.419  0.141  1.0
  Na  Na5  1  0.551  0.081  0.359  1.0
  Na  Na6  1  0.949  0.919  0.859  1.0
  Na  Na7  1  0.449  0.581  0.641  1.0
  Na  Na8  1  0.949  0.581  0.859  1.0
  Na  Na9  1  0.449  0.919  0.641  1.0
  Na  Na10  1  0.051  0.081  0.141  1.0
  Na  Na11  1  0.551  0.419  0.359  1.0
  Fe  Fe12  1  0.046  0.373  0.471  1.0
  Fe  Fe13  1  0.546  0.127  0.029  1.0
  Fe  Fe14  1  0.954  0.873  0.529  1.0
  Fe  Fe15  1  0.454  0.627  0.971  1.0
  Fe  Fe16  1  0.954  0.627  0.529  1.0
  Fe  Fe17  1  0.454  0.873  0.971  1.0
  Fe  Fe18  1  0.046  0.127  0.471  1.0
  Fe  Fe19  1  0.546  0.373  0.029  1.0
  Se  Se20  1  0.313  0.250  0.539  1.0
  Se  Se21  1  0.813  0.250  0.961  1.0
  Se  Se22  1  0.687  0.750  0.461  1.0
  Se  Se23  1  0.187  0.750  0.039  1.0
  Se  Se24  1  0.379  0.250  0.171  1.0
  Se  Se25  1  0.879  0.250  0.329  1.0
  Se  Se26  1  0.621  0.750  0.829  1.0
  Se  Se27  1  0.121  0.750  0.671  1.0
  Se  Se28  1  0.172  0.555  0.377  1.0
  Se  Se29  1  0.672  0.945  0.123  1.0
  Se  Se30  1  0.828  0.055  0.623  1.0
  Se  Se31  1  0.328  0.445  0.877  1.0
  Se  Se32  1  0.828  0.445  0.623  1.0
  Se  Se33  1  0.328  0.055  0.877  1.0
  Se  Se34  1  0.172  0.945  0.377  1.0
  Se  Se35  1  0.672  0.555  0.123  1.0
[/CIF]
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