The compound described by Tl3SnSe4 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 4-coordinate geometry to one Se(1), one Se(3), and two equivalent Se(4) atoms. In the second Tl site, Tl(2) is bonded in a 4-coordinate geometry to one Se(1), one Se(2), one Se(3), and one Se(4) atom. In the third Tl site, Tl(3) is bonded to one Se(1), one Se(3), and two equivalent Se(2) atoms to form TlSe4 trigonal pyramids that share corners with two equivalent Sn(1)Se4 tetrahedra, corners with two equivalent Tl(3)Se4 trigonal pyramids, and  an edgeedge with one Sn(1)Se4 tetrahedra. 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 two equivalent Tl(3)Se4 trigonal pyramids and  an edgeedge with one Tl(3)Se4 trigonal pyramid. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Tl(1), one Tl(2), one Tl(3), and one Sn(1) atom. In the second Se site, Se(2) is bonded in a 4-coordinate geometry to one Tl(2), two equivalent Tl(3), and one Sn(1) atom. In the third Se site, Se(3) is bonded to one Tl(1), one Tl(2), one Tl(3), and one Sn(1) atom to form a mixture of distorted corner and edge-sharing SeTl3Sn trigonal pyramids. In the fourth Se site, Se(4) is bonded to one Tl(2), two equivalent Tl(1), and one Sn(1) atom to form a mixture of distorted corner and edge-sharing SeTl3Sn trigonal pyramids. is represented by the CIF file [CIF]
data_Tl3SnSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.425
_cell_length_b   8.369
_cell_length_c   15.293
_cell_angle_alpha   80.769
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1064.325
_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
  Tl  Tl0  1  0.025  0.492  0.617  1.0
  Tl  Tl1  1  0.525  0.508  0.883  1.0
  Tl  Tl2  1  0.975  0.508  0.383  1.0
  Tl  Tl3  1  0.475  0.492  0.117  1.0
  Tl  Tl4  1  0.392  0.266  0.637  1.0
  Tl  Tl5  1  0.892  0.734  0.863  1.0
  Tl  Tl6  1  0.608  0.734  0.363  1.0
  Tl  Tl7  1  0.108  0.266  0.137  1.0
  Tl  Tl8  1  0.827  0.098  0.614  1.0
  Tl  Tl9  1  0.327  0.902  0.886  1.0
  Tl  Tl10  1  0.173  0.902  0.386  1.0
  Tl  Tl11  1  0.673  0.098  0.114  1.0
  Sn  Sn12  1  0.598  0.702  0.624  1.0
  Sn  Sn13  1  0.098  0.298  0.876  1.0
  Sn  Sn14  1  0.402  0.298  0.376  1.0
  Sn  Sn15  1  0.902  0.702  0.124  1.0
  Se  Se16  1  0.642  0.335  0.474  1.0
  Se  Se17  1  0.142  0.665  0.026  1.0
  Se  Se18  1  0.358  0.665  0.526  1.0
  Se  Se19  1  0.858  0.335  0.974  1.0
  Se  Se20  1  0.570  0.918  0.728  1.0
  Se  Se21  1  0.070  0.082  0.772  1.0
  Se  Se22  1  0.430  0.082  0.272  1.0
  Se  Se23  1  0.930  0.918  0.228  1.0
  Se  Se24  1  0.659  0.805  0.025  1.0
  Se  Se25  1  0.159  0.195  0.475  1.0
  Se  Se26  1  0.341  0.195  0.975  1.0
  Se  Se27  1  0.841  0.805  0.525  1.0
  Se  Se28  1  0.194  0.563  0.782  1.0
  Se  Se29  1  0.694  0.437  0.718  1.0
  Se  Se30  1  0.806  0.437  0.218  1.0
  Se  Se31  1  0.306  0.563  0.282  1.0
[/CIF]
.
The compound described by Tl3SnSe4 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 4-coordinate geometry to one Se(1), one Se(3), and two equivalent Se(4) atoms. In the second Tl site, Tl(2) is bonded in a 4-coordinate geometry to one Se(1), one Se(2), one Se(3), and one Se(4) atom. In the third Tl site, Tl(3) is bonded to one Se(1), one Se(3), and two equivalent Se(2) atoms to form TlSe4 trigonal pyramids that share corners with two equivalent Sn(1)Se4 tetrahedra, corners with two equivalent Tl(3)Se4 trigonal pyramids, and  an edgeedge with one Sn(1)Se4 tetrahedra. 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 two equivalent Tl(3)Se4 trigonal pyramids and  an edgeedge with one Tl(3)Se4 trigonal pyramid. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Tl(1), one Tl(2), one Tl(3), and one Sn(1) atom. In the second Se site, Se(2) is bonded in a 4-coordinate geometry to one Tl(2), two equivalent Tl(3), and one Sn(1) atom. In the third Se site, Se(3) is bonded to one Tl(1), one Tl(2), one Tl(3), and one Sn(1) atom to form a mixture of distorted corner and edge-sharing SeTl3Sn trigonal pyramids. In the fourth Se site, Se(4) is bonded to one Tl(2), two equivalent Tl(1), and one Sn(1) atom to form a mixture of distorted corner and edge-sharing SeTl3Sn trigonal pyramids. is represented by the CIF file [CIF]
data_Tl3SnSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.425
_cell_length_b   8.369
_cell_length_c   15.293
_cell_angle_alpha   80.769
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1064.325
_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
  Tl  Tl0  1  0.025  0.492  0.617  1.0
  Tl  Tl1  1  0.525  0.508  0.883  1.0
  Tl  Tl2  1  0.975  0.508  0.383  1.0
  Tl  Tl3  1  0.475  0.492  0.117  1.0
  Tl  Tl4  1  0.392  0.266  0.637  1.0
  Tl  Tl5  1  0.892  0.734  0.863  1.0
  Tl  Tl6  1  0.608  0.734  0.363  1.0
  Tl  Tl7  1  0.108  0.266  0.137  1.0
  Tl  Tl8  1  0.827  0.098  0.614  1.0
  Tl  Tl9  1  0.327  0.902  0.886  1.0
  Tl  Tl10  1  0.173  0.902  0.386  1.0
  Tl  Tl11  1  0.673  0.098  0.114  1.0
  Sn  Sn12  1  0.598  0.702  0.624  1.0
  Sn  Sn13  1  0.098  0.298  0.876  1.0
  Sn  Sn14  1  0.402  0.298  0.376  1.0
  Sn  Sn15  1  0.902  0.702  0.124  1.0
  Se  Se16  1  0.642  0.335  0.474  1.0
  Se  Se17  1  0.142  0.665  0.026  1.0
  Se  Se18  1  0.358  0.665  0.526  1.0
  Se  Se19  1  0.858  0.335  0.974  1.0
  Se  Se20  1  0.570  0.918  0.728  1.0
  Se  Se21  1  0.070  0.082  0.772  1.0
  Se  Se22  1  0.430  0.082  0.272  1.0
  Se  Se23  1  0.930  0.918  0.228  1.0
  Se  Se24  1  0.659  0.805  0.025  1.0
  Se  Se25  1  0.159  0.195  0.475  1.0
  Se  Se26  1  0.341  0.195  0.975  1.0
  Se  Se27  1  0.841  0.805  0.525  1.0
  Se  Se28  1  0.194  0.563  0.782  1.0
  Se  Se29  1  0.694  0.437  0.718  1.0
  Se  Se30  1  0.806  0.437  0.218  1.0
  Se  Se31  1  0.306  0.563  0.282  1.0
[/CIF]
.