The crystal structure described by Ta11(SiSe4)2 crystallizes in the orthorhombic Pnnm space group. There are six inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(1), and two equivalent Se(3) atoms. In the second Ta site, Ta(2) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(2), and two equivalent Se(3) atoms. In the third Ta site, Ta(3) is bonded in a 5-coordinate geometry to one Si(1), two equivalent Se(1), and two equivalent Se(4) atoms. In the fourth Ta site, Ta(4) is bonded in a distorted square co-planar geometry to two equivalent Si(1) and two equivalent Se(3) atoms. In the fifth Ta site, Ta(5) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(4), and two equivalent Se(1) atoms. In the sixth Ta site, Ta(6) is bonded in a 5-coordinate geometry to one Si(1), one Se(1), one Se(4), and two equivalent Se(2) atoms. Si(1) is bonded in a 9-coordinate geometry to one Ta(3), one Ta(4), one Ta(6), two equivalent Ta(1), two equivalent Ta(2), and two equivalent Ta(5) atoms. There are four inequivalent Se sites. In the first Se site, Se(3) is bonded in a 5-coordinate geometry to one Ta(4), two equivalent Ta(1), and two equivalent Ta(2) atoms. In the second Se site, Se(4) is bonded in a 4-coordinate geometry to one Ta(5), one Ta(6), and two equivalent Ta(3) atoms. In the third Se site, Se(1) is bonded in a 6-coordinate geometry to one Ta(1), one Ta(6), two equivalent Ta(3), and two equivalent Ta(5) atoms. In the fourth Se site, Se(2) is bonded in a distorted T-shaped geometry to one Ta(2) and two equivalent Ta(6) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ta11(SiSe4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.481
_cell_length_b   11.932
_cell_length_c   19.549
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   811.990
_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
  Ta  Ta0  1  0.000  0.565  0.113  1.0
  Ta  Ta1  1  0.000  0.435  0.887  1.0
  Ta  Ta2  1  0.500  0.935  0.613  1.0
  Ta  Ta3  1  0.500  0.065  0.387  1.0
  Ta  Ta4  1  0.000  0.322  0.047  1.0
  Ta  Ta5  1  0.000  0.678  0.953  1.0
  Ta  Ta6  1  0.500  0.178  0.547  1.0
  Ta  Ta7  1  0.500  0.822  0.453  1.0
  Ta  Ta8  1  0.000  0.050  0.260  1.0
  Ta  Ta9  1  0.000  0.950  0.740  1.0
  Ta  Ta10  1  0.500  0.450  0.760  1.0
  Ta  Ta11  1  0.500  0.550  0.240  1.0
  Ta  Ta12  1  0.000  1.000  0.500  1.0
  Ta  Ta13  1  0.500  0.500  0.000  1.0
  Ta  Ta14  1  0.000  0.341  0.212  1.0
  Ta  Ta15  1  0.000  0.659  0.788  1.0
  Ta  Ta16  1  0.500  0.159  0.712  1.0
  Ta  Ta17  1  0.500  0.841  0.288  1.0
  Ta  Ta18  1  0.000  0.319  0.644  1.0
  Ta  Ta19  1  0.000  0.681  0.356  1.0
  Ta  Ta20  1  0.500  0.181  0.144  1.0
  Ta  Ta21  1  0.500  0.819  0.856  1.0
  Si  Si22  1  0.000  0.091  0.627  1.0
  Si  Si23  1  0.000  0.908  0.373  1.0
  Si  Si24  1  0.500  0.408  0.127  1.0
  Si  Si25  1  0.500  0.591  0.873  1.0
  Se  Se26  1  0.000  0.716  0.213  1.0
  Se  Se27  1  0.000  0.284  0.787  1.0
  Se  Se28  1  0.500  0.784  0.713  1.0
  Se  Se29  1  0.500  0.216  0.287  1.0
  Se  Se30  1  0.000  0.109  0.055  1.0
  Se  Se31  1  0.000  0.891  0.945  1.0
  Se  Se32  1  0.500  0.391  0.555  1.0
  Se  Se33  1  0.500  0.609  0.445  1.0
  Se  Se34  1  0.000  0.213  0.443  1.0
  Se  Se35  1  0.000  0.787  0.557  1.0
  Se  Se36  1  0.500  0.287  0.943  1.0
  Se  Se37  1  0.500  0.713  0.057  1.0
  Se  Se38  1  0.000  0.463  0.325  1.0
  Se  Se39  1  0.000  0.537  0.675  1.0
  Se  Se40  1  0.500  0.037  0.825  1.0
  Se  Se41  1  0.500  0.963  0.175  1.0
[/CIF]
.
The crystal structure described by Ta11(SiSe4)2 crystallizes in the orthorhombic Pnnm space group. There are six inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(1), and two equivalent Se(3) atoms. In the second Ta site, Ta(2) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(2), and two equivalent Se(3) atoms. In the third Ta site, Ta(3) is bonded in a 5-coordinate geometry to one Si(1), two equivalent Se(1), and two equivalent Se(4) atoms. In the fourth Ta site, Ta(4) is bonded in a distorted square co-planar geometry to two equivalent Si(1) and two equivalent Se(3) atoms. In the fifth Ta site, Ta(5) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(4), and two equivalent Se(1) atoms. In the sixth Ta site, Ta(6) is bonded in a 5-coordinate geometry to one Si(1), one Se(1), one Se(4), and two equivalent Se(2) atoms. Si(1) is bonded in a 9-coordinate geometry to one Ta(3), one Ta(4), one Ta(6), two equivalent Ta(1), two equivalent Ta(2), and two equivalent Ta(5) atoms. There are four inequivalent Se sites. In the first Se site, Se(3) is bonded in a 5-coordinate geometry to one Ta(4), two equivalent Ta(1), and two equivalent Ta(2) atoms. In the second Se site, Se(4) is bonded in a 4-coordinate geometry to one Ta(5), one Ta(6), and two equivalent Ta(3) atoms. In the third Se site, Se(1) is bonded in a 6-coordinate geometry to one Ta(1), one Ta(6), two equivalent Ta(3), and two equivalent Ta(5) atoms. In the fourth Se site, Se(2) is bonded in a distorted T-shaped geometry to one Ta(2) and two equivalent Ta(6) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ta11(SiSe4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.481
_cell_length_b   11.932
_cell_length_c   19.549
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   811.990
_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
  Ta  Ta0  1  0.000  0.565  0.113  1.0
  Ta  Ta1  1  0.000  0.435  0.887  1.0
  Ta  Ta2  1  0.500  0.935  0.613  1.0
  Ta  Ta3  1  0.500  0.065  0.387  1.0
  Ta  Ta4  1  0.000  0.322  0.047  1.0
  Ta  Ta5  1  0.000  0.678  0.953  1.0
  Ta  Ta6  1  0.500  0.178  0.547  1.0
  Ta  Ta7  1  0.500  0.822  0.453  1.0
  Ta  Ta8  1  0.000  0.050  0.260  1.0
  Ta  Ta9  1  0.000  0.950  0.740  1.0
  Ta  Ta10  1  0.500  0.450  0.760  1.0
  Ta  Ta11  1  0.500  0.550  0.240  1.0
  Ta  Ta12  1  0.000  1.000  0.500  1.0
  Ta  Ta13  1  0.500  0.500  0.000  1.0
  Ta  Ta14  1  0.000  0.341  0.212  1.0
  Ta  Ta15  1  0.000  0.659  0.788  1.0
  Ta  Ta16  1  0.500  0.159  0.712  1.0
  Ta  Ta17  1  0.500  0.841  0.288  1.0
  Ta  Ta18  1  0.000  0.319  0.644  1.0
  Ta  Ta19  1  0.000  0.681  0.356  1.0
  Ta  Ta20  1  0.500  0.181  0.144  1.0
  Ta  Ta21  1  0.500  0.819  0.856  1.0
  Si  Si22  1  0.000  0.091  0.627  1.0
  Si  Si23  1  0.000  0.908  0.373  1.0
  Si  Si24  1  0.500  0.408  0.127  1.0
  Si  Si25  1  0.500  0.591  0.873  1.0
  Se  Se26  1  0.000  0.716  0.213  1.0
  Se  Se27  1  0.000  0.284  0.787  1.0
  Se  Se28  1  0.500  0.784  0.713  1.0
  Se  Se29  1  0.500  0.216  0.287  1.0
  Se  Se30  1  0.000  0.109  0.055  1.0
  Se  Se31  1  0.000  0.891  0.945  1.0
  Se  Se32  1  0.500  0.391  0.555  1.0
  Se  Se33  1  0.500  0.609  0.445  1.0
  Se  Se34  1  0.000  0.213  0.443  1.0
  Se  Se35  1  0.000  0.787  0.557  1.0
  Se  Se36  1  0.500  0.287  0.943  1.0
  Se  Se37  1  0.500  0.713  0.057  1.0
  Se  Se38  1  0.000  0.463  0.325  1.0
  Se  Se39  1  0.000  0.537  0.675  1.0
  Se  Se40  1  0.500  0.037  0.825  1.0
  Se  Se41  1  0.500  0.963  0.175  1.0
[/CIF]
.