The structure described by Na3CuSnSe4 crystallizes in the monoclinic P2_1/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 Se(1), one Se(4), two equivalent Se(2), and two equivalent Se(3) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one Se(2), one Se(3), one Se(4), and two equivalent Se(1) atoms. In the third Na site, Na(3) is bonded to one Se(1), one Se(2), one Se(3), and two equivalent Se(4) atoms to form distorted NaSe5 square pyramids that share corners with three equivalent Sn(1)Se4 tetrahedra,  an edgeedge with one Na(3)Se5 square pyramid, and  an edgeedge with one Sn(1)Se4 tetrahedra. Cu(1) is bonded in a 4-coordinate geometry to one Se(1), one Se(2), one Se(3), and one Se(4) atom. Sn(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form SnSe4 tetrahedra that share corners with three equivalent Na(3)Se5 square pyramids and  an edgeedge with one Na(3)Se5 square pyramid. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Na(1), one Na(3), two equivalent Na(2), one Cu(1), and one Sn(1) atom. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one Na(2), one Na(3), two equivalent Na(1), one Cu(1), and one Sn(1) atom. In the third Se site, Se(3) is bonded to one Na(2), one Na(3), two equivalent Na(1), one Cu(1), and one Sn(1) atom to form a mixture of distorted corner and edge-sharing SeNa4CuSn pentagonal pyramids. In the fourth Se site, Se(4) is bonded to one Na(1), one Na(2), two equivalent Na(3), one Cu(1), and one Sn(1) atom to form a mixture of distorted corner and edge-sharing SeNa4CuSn pentagonal pyramids. is represented by the CIF file [CIF]
data_Na3CuSnSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.320
_cell_length_b   6.907
_cell_length_c   14.804
_cell_angle_alpha   62.670
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   937.512
_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  0.897  0.742  0.483  1.0
  Na  Na1  1  0.361  0.827  0.624  1.0
  Na  Na2  1  0.397  0.258  0.017  1.0
  Na  Na3  1  0.639  0.173  0.376  1.0
  Na  Na4  1  0.883  0.388  0.125  1.0
  Na  Na5  1  0.617  0.388  0.625  1.0
  Na  Na6  1  0.603  0.742  0.983  1.0
  Na  Na7  1  0.383  0.612  0.375  1.0
  Na  Na8  1  0.139  0.827  0.124  1.0
  Na  Na9  1  0.861  0.173  0.876  1.0
  Na  Na10  1  0.117  0.612  0.875  1.0
  Na  Na11  1  0.103  0.258  0.517  1.0
  Cu  Cu12  1  0.602  0.621  0.786  1.0
  Cu  Cu13  1  0.102  0.379  0.714  1.0
  Cu  Cu14  1  0.398  0.379  0.214  1.0
  Cu  Cu15  1  0.898  0.621  0.286  1.0
  Sn  Sn16  1  0.861  0.890  0.695  1.0
  Sn  Sn17  1  0.639  0.890  0.195  1.0
  Sn  Sn18  1  0.361  0.110  0.805  1.0
  Sn  Sn19  1  0.139  0.110  0.305  1.0
  Se  Se20  1  0.158  0.144  0.898  1.0
  Se  Se21  1  0.928  0.230  0.357  1.0
  Se  Se22  1  0.897  0.286  0.659  1.0
  Se  Se23  1  0.681  0.621  0.383  1.0
  Se  Se24  1  0.572  0.230  0.857  1.0
  Se  Se25  1  0.658  0.856  0.602  1.0
  Se  Se26  1  0.103  0.714  0.341  1.0
  Se  Se27  1  0.072  0.770  0.643  1.0
  Se  Se28  1  0.319  0.379  0.617  1.0
  Se  Se29  1  0.428  0.770  0.143  1.0
  Se  Se30  1  0.603  0.286  0.159  1.0
  Se  Se31  1  0.397  0.714  0.841  1.0
  Se  Se32  1  0.342  0.144  0.398  1.0
  Se  Se33  1  0.181  0.379  0.117  1.0
  Se  Se34  1  0.842  0.856  0.102  1.0
  Se  Se35  1  0.819  0.621  0.883  1.0
[/CIF]
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The structure described by Na3CuSnSe4 crystallizes in the monoclinic P2_1/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 Se(1), one Se(4), two equivalent Se(2), and two equivalent Se(3) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one Se(2), one Se(3), one Se(4), and two equivalent Se(1) atoms. In the third Na site, Na(3) is bonded to one Se(1), one Se(2), one Se(3), and two equivalent Se(4) atoms to form distorted NaSe5 square pyramids that share corners with three equivalent Sn(1)Se4 tetrahedra,  an edgeedge with one Na(3)Se5 square pyramid, and  an edgeedge with one Sn(1)Se4 tetrahedra. Cu(1) is bonded in a 4-coordinate geometry to one Se(1), one Se(2), one Se(3), and one Se(4) atom. Sn(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form SnSe4 tetrahedra that share corners with three equivalent Na(3)Se5 square pyramids and  an edgeedge with one Na(3)Se5 square pyramid. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Na(1), one Na(3), two equivalent Na(2), one Cu(1), and one Sn(1) atom. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one Na(2), one Na(3), two equivalent Na(1), one Cu(1), and one Sn(1) atom. In the third Se site, Se(3) is bonded to one Na(2), one Na(3), two equivalent Na(1), one Cu(1), and one Sn(1) atom to form a mixture of distorted corner and edge-sharing SeNa4CuSn pentagonal pyramids. In the fourth Se site, Se(4) is bonded to one Na(1), one Na(2), two equivalent Na(3), one Cu(1), and one Sn(1) atom to form a mixture of distorted corner and edge-sharing SeNa4CuSn pentagonal pyramids. is represented by the CIF file [CIF]
data_Na3CuSnSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.320
_cell_length_b   6.907
_cell_length_c   14.804
_cell_angle_alpha   62.670
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   937.512
_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  0.897  0.742  0.483  1.0
  Na  Na1  1  0.361  0.827  0.624  1.0
  Na  Na2  1  0.397  0.258  0.017  1.0
  Na  Na3  1  0.639  0.173  0.376  1.0
  Na  Na4  1  0.883  0.388  0.125  1.0
  Na  Na5  1  0.617  0.388  0.625  1.0
  Na  Na6  1  0.603  0.742  0.983  1.0
  Na  Na7  1  0.383  0.612  0.375  1.0
  Na  Na8  1  0.139  0.827  0.124  1.0
  Na  Na9  1  0.861  0.173  0.876  1.0
  Na  Na10  1  0.117  0.612  0.875  1.0
  Na  Na11  1  0.103  0.258  0.517  1.0
  Cu  Cu12  1  0.602  0.621  0.786  1.0
  Cu  Cu13  1  0.102  0.379  0.714  1.0
  Cu  Cu14  1  0.398  0.379  0.214  1.0
  Cu  Cu15  1  0.898  0.621  0.286  1.0
  Sn  Sn16  1  0.861  0.890  0.695  1.0
  Sn  Sn17  1  0.639  0.890  0.195  1.0
  Sn  Sn18  1  0.361  0.110  0.805  1.0
  Sn  Sn19  1  0.139  0.110  0.305  1.0
  Se  Se20  1  0.158  0.144  0.898  1.0
  Se  Se21  1  0.928  0.230  0.357  1.0
  Se  Se22  1  0.897  0.286  0.659  1.0
  Se  Se23  1  0.681  0.621  0.383  1.0
  Se  Se24  1  0.572  0.230  0.857  1.0
  Se  Se25  1  0.658  0.856  0.602  1.0
  Se  Se26  1  0.103  0.714  0.341  1.0
  Se  Se27  1  0.072  0.770  0.643  1.0
  Se  Se28  1  0.319  0.379  0.617  1.0
  Se  Se29  1  0.428  0.770  0.143  1.0
  Se  Se30  1  0.603  0.286  0.159  1.0
  Se  Se31  1  0.397  0.714  0.841  1.0
  Se  Se32  1  0.342  0.144  0.398  1.0
  Se  Se33  1  0.181  0.379  0.117  1.0
  Se  Se34  1  0.842  0.856  0.102  1.0
  Se  Se35  1  0.819  0.621  0.883  1.0
[/CIF]
.