The compound described by Tl2B2Se7 crystallizes in the monoclinic C2/c space group. Tl(1) is bonded in a 6-coordinate geometry to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms. B(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form corner-sharing BSe4 tetrahedra. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to two equivalent Tl(1) and one B(1) atom. In the second Se site, Se(2) is bonded in a distorted single-bond geometry to two equivalent Tl(1) and one B(1) atom. In the third Se site, Se(3) is bonded in a distorted single-bond geometry to two equivalent Tl(1) and one B(1) atom. In the fourth Se site, Se(4) is bonded in a water-like geometry to two equivalent B(1) atoms. is represented by the CIF file [CIF]
data_Tl2B2Se7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.560
_cell_length_b   8.560
_cell_length_c   12.172
_cell_angle_alpha   62.620
_cell_angle_beta   62.620
_cell_angle_gamma   49.935
_symmetry_Int_Tables_number   1
_cell_volume   588.262
_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
  Tl  Tl0  1  0.114  0.677  0.531  1.0
  Tl  Tl1  1  0.323  0.886  0.969  1.0
  Tl  Tl2  1  0.886  0.323  0.469  1.0
  Tl  Tl3  1  0.677  0.114  0.031  1.0
  B  B4  1  0.605  0.163  0.350  1.0
  B  B5  1  0.837  0.395  0.150  1.0
  B  B6  1  0.395  0.837  0.650  1.0
  B  B7  1  0.163  0.605  0.850  1.0
  Se  Se8  1  0.177  0.563  0.025  1.0
  Se  Se9  1  0.437  0.823  0.475  1.0
  Se  Se10  1  0.823  0.437  0.975  1.0
  Se  Se11  1  0.563  0.177  0.525  1.0
  Se  Se12  1  0.151  0.387  0.831  1.0
  Se  Se13  1  0.613  0.849  0.669  1.0
  Se  Se14  1  0.849  0.613  0.169  1.0
  Se  Se15  1  0.387  0.151  0.331  1.0
  Se  Se16  1  0.936  0.897  0.771  1.0
  Se  Se17  1  0.103  0.064  0.729  1.0
  Se  Se18  1  0.064  0.103  0.229  1.0
  Se  Se19  1  0.897  0.936  0.271  1.0
  Se  Se20  1  0.463  0.537  0.750  1.0
  Se  Se21  1  0.537  0.463  0.250  1.0
[/CIF]
.
The compound described by Tl2B2Se7 crystallizes in the monoclinic C2/c space group. Tl(1) is bonded in a 6-coordinate geometry to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms. B(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form corner-sharing BSe4 tetrahedra. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to two equivalent Tl(1) and one B(1) atom. In the second Se site, Se(2) is bonded in a distorted single-bond geometry to two equivalent Tl(1) and one B(1) atom. In the third Se site, Se(3) is bonded in a distorted single-bond geometry to two equivalent Tl(1) and one B(1) atom. In the fourth Se site, Se(4) is bonded in a water-like geometry to two equivalent B(1) atoms. is represented by the CIF file [CIF]
data_Tl2B2Se7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.560
_cell_length_b   8.560
_cell_length_c   12.172
_cell_angle_alpha   62.620
_cell_angle_beta   62.620
_cell_angle_gamma   49.935
_symmetry_Int_Tables_number   1
_cell_volume   588.262
_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
  Tl  Tl0  1  0.114  0.677  0.531  1.0
  Tl  Tl1  1  0.323  0.886  0.969  1.0
  Tl  Tl2  1  0.886  0.323  0.469  1.0
  Tl  Tl3  1  0.677  0.114  0.031  1.0
  B  B4  1  0.605  0.163  0.350  1.0
  B  B5  1  0.837  0.395  0.150  1.0
  B  B6  1  0.395  0.837  0.650  1.0
  B  B7  1  0.163  0.605  0.850  1.0
  Se  Se8  1  0.177  0.563  0.025  1.0
  Se  Se9  1  0.437  0.823  0.475  1.0
  Se  Se10  1  0.823  0.437  0.975  1.0
  Se  Se11  1  0.563  0.177  0.525  1.0
  Se  Se12  1  0.151  0.387  0.831  1.0
  Se  Se13  1  0.613  0.849  0.669  1.0
  Se  Se14  1  0.849  0.613  0.169  1.0
  Se  Se15  1  0.387  0.151  0.331  1.0
  Se  Se16  1  0.936  0.897  0.771  1.0
  Se  Se17  1  0.103  0.064  0.729  1.0
  Se  Se18  1  0.064  0.103  0.229  1.0
  Se  Se19  1  0.897  0.936  0.271  1.0
  Se  Se20  1  0.463  0.537  0.750  1.0
  Se  Se21  1  0.537  0.463  0.250  1.0
[/CIF]
.