The material described by TbB18Si4C crystallizes in the monoclinic C2/m space group. Tb(1) is bonded in a 18-coordinate geometry to two equivalent B(10), two equivalent B(3), two equivalent B(4), two equivalent B(6), two equivalent B(7), two equivalent B(9), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. There are ten inequivalent B sites. In the first B site, B(5) is bonded in a 6-coordinate geometry to one B(1), one B(10), one B(3), one B(6), one B(8), and one Si(2) atom. In the second B site, B(6) is bonded in a 7-coordinate geometry to one Tb(1), one B(1), one B(10), one B(3), one B(5), one B(8), and one Si(3) atom. In the third B site, B(7) is bonded in a 7-coordinate geometry to one Tb(1), one B(2), one B(4), one B(7), two equivalent B(9), and one Si(2) atom. In the fourth B site, B(8) is bonded in a 6-coordinate geometry to one B(1), one B(10), one B(3), one B(5), one B(6), and one B(8) atom. In the fifth B site, B(9) is bonded in a 7-coordinate geometry to one Tb(1), one B(10), one B(2), one B(4), one B(9), and two equivalent B(7) atoms. In the sixth B site, B(10) is bonded in a 7-coordinate geometry to one Tb(1), one B(1), one B(3), one B(5), one B(6), one B(8), and one B(9) atom. In the seventh B site, B(1) is bonded in a distorted single-bond geometry to one B(10), one B(3), one B(5), one B(6), one B(8), and one C(1) atom. In the eighth B site, B(2) is bonded in a single-bond geometry to one B(4), two equivalent B(7), two equivalent B(9), and one C(1) atom. In the ninth B site, B(3) is bonded in a 7-coordinate geometry to one Tb(1), one B(1), one B(10), one B(5), one B(6), one B(8), and one Si(2) atom. In the tenth B site, B(4) is bonded in a 8-coordinate geometry to two equivalent Tb(1), one B(2), two equivalent B(7), two equivalent B(9), and one Si(3) atom. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to two equivalent Tb(1), one Si(1), one Si(3), and two equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 5-coordinate geometry to one Tb(1), one B(3), one B(5), one B(7), and one Si(1) atom. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to two equivalent Tb(1), one B(4), two equivalent B(6), and one Si(1) atom. C(1) is bonded in a distorted tetrahedral geometry to one B(2), two equivalent B(1), and one C(1) atom. is represented by the CIF file [CIF]
data_TbSi4B18C
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.936
_cell_length_b   7.936
_cell_length_c   7.911
_cell_angle_alpha   78.425
_cell_angle_beta   78.425
_cell_angle_gamma   78.290
_symmetry_Int_Tables_number   1
_cell_volume   471.224
_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
  Tb  Tb0  1  0.000  0.500  0.500  1.0
  Tb  Tb1  1  0.500  0.000  0.500  1.0
  Si  Si2  1  0.571  0.571  0.572  1.0
  Si  Si3  1  0.429  0.429  0.428  1.0
  Si  Si4  1  0.731  0.346  0.745  1.0
  Si  Si5  1  0.736  0.736  0.338  1.0
  Si  Si6  1  0.346  0.731  0.745  1.0
  Si  Si7  1  0.269  0.654  0.255  1.0
  Si  Si8  1  0.264  0.264  0.662  1.0
  Si  Si9  1  0.654  0.269  0.255  1.0
  B  B10  1  0.728  0.988  0.988  1.0
  B  B11  1  0.988  0.728  0.988  1.0
  B  B12  1  0.988  0.988  0.730  1.0
  B  B13  1  0.272  0.012  0.012  1.0
  B  B14  1  0.012  0.272  0.012  1.0
  B  B15  1  0.012  0.012  0.270  1.0
  B  B16  1  0.560  0.124  0.124  1.0
  B  B17  1  0.124  0.560  0.124  1.0
  B  B18  1  0.124  0.124  0.562  1.0
  B  B19  1  0.440  0.876  0.876  1.0
  B  B20  1  0.876  0.440  0.876  1.0
  B  B21  1  0.876  0.876  0.438  1.0
  B  B22  1  0.585  0.177  0.895  1.0
  B  B23  1  0.893  0.585  0.173  1.0
  B  B24  1  0.178  0.891  0.587  1.0
  B  B25  1  0.891  0.178  0.587  1.0
  B  B26  1  0.585  0.893  0.173  1.0
  B  B27  1  0.177  0.585  0.895  1.0
  B  B28  1  0.415  0.823  0.105  1.0
  B  B29  1  0.107  0.415  0.827  1.0
  B  B30  1  0.822  0.109  0.413  1.0
  B  B31  1  0.109  0.822  0.413  1.0
  B  B32  1  0.415  0.107  0.827  1.0
  B  B33  1  0.823  0.415  0.105  1.0
  B  B34  1  0.202  0.372  0.021  1.0
  B  B35  1  0.019  0.198  0.372  1.0
  B  B36  1  0.372  0.020  0.197  1.0
  B  B37  1  0.020  0.372  0.197  1.0
  B  B38  1  0.198  0.019  0.372  1.0
  B  B39  1  0.372  0.202  0.021  1.0
  B  B40  1  0.798  0.628  0.979  1.0
  B  B41  1  0.981  0.802  0.628  1.0
  B  B42  1  0.628  0.980  0.803  1.0
  B  B43  1  0.980  0.628  0.803  1.0
  B  B44  1  0.802  0.981  0.628  1.0
  B  B45  1  0.628  0.798  0.979  1.0
  C  C46  1  0.949  0.949  0.949  1.0
  C  C47  1  0.051  0.051  0.051  1.0
[/CIF]
.
The material described by TbB18Si4C crystallizes in the monoclinic C2/m space group. Tb(1) is bonded in a 18-coordinate geometry to two equivalent B(10), two equivalent B(3), two equivalent B(4), two equivalent B(6), two equivalent B(7), two equivalent B(9), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. There are ten inequivalent B sites. In the first B site, B(5) is bonded in a 6-coordinate geometry to one B(1), one B(10), one B(3), one B(6), one B(8), and one Si(2) atom. In the second B site, B(6) is bonded in a 7-coordinate geometry to one Tb(1), one B(1), one B(10), one B(3), one B(5), one B(8), and one Si(3) atom. In the third B site, B(7) is bonded in a 7-coordinate geometry to one Tb(1), one B(2), one B(4), one B(7), two equivalent B(9), and one Si(2) atom. In the fourth B site, B(8) is bonded in a 6-coordinate geometry to one B(1), one B(10), one B(3), one B(5), one B(6), and one B(8) atom. In the fifth B site, B(9) is bonded in a 7-coordinate geometry to one Tb(1), one B(10), one B(2), one B(4), one B(9), and two equivalent B(7) atoms. In the sixth B site, B(10) is bonded in a 7-coordinate geometry to one Tb(1), one B(1), one B(3), one B(5), one B(6), one B(8), and one B(9) atom. In the seventh B site, B(1) is bonded in a distorted single-bond geometry to one B(10), one B(3), one B(5), one B(6), one B(8), and one C(1) atom. In the eighth B site, B(2) is bonded in a single-bond geometry to one B(4), two equivalent B(7), two equivalent B(9), and one C(1) atom. In the ninth B site, B(3) is bonded in a 7-coordinate geometry to one Tb(1), one B(1), one B(10), one B(5), one B(6), one B(8), and one Si(2) atom. In the tenth B site, B(4) is bonded in a 8-coordinate geometry to two equivalent Tb(1), one B(2), two equivalent B(7), two equivalent B(9), and one Si(3) atom. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to two equivalent Tb(1), one Si(1), one Si(3), and two equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 5-coordinate geometry to one Tb(1), one B(3), one B(5), one B(7), and one Si(1) atom. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to two equivalent Tb(1), one B(4), two equivalent B(6), and one Si(1) atom. C(1) is bonded in a distorted tetrahedral geometry to one B(2), two equivalent B(1), and one C(1) atom. is represented by the CIF file [CIF]
data_TbSi4B18C
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.936
_cell_length_b   7.936
_cell_length_c   7.911
_cell_angle_alpha   78.425
_cell_angle_beta   78.425
_cell_angle_gamma   78.290
_symmetry_Int_Tables_number   1
_cell_volume   471.224
_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
  Tb  Tb0  1  0.000  0.500  0.500  1.0
  Tb  Tb1  1  0.500  0.000  0.500  1.0
  Si  Si2  1  0.571  0.571  0.572  1.0
  Si  Si3  1  0.429  0.429  0.428  1.0
  Si  Si4  1  0.731  0.346  0.745  1.0
  Si  Si5  1  0.736  0.736  0.338  1.0
  Si  Si6  1  0.346  0.731  0.745  1.0
  Si  Si7  1  0.269  0.654  0.255  1.0
  Si  Si8  1  0.264  0.264  0.662  1.0
  Si  Si9  1  0.654  0.269  0.255  1.0
  B  B10  1  0.728  0.988  0.988  1.0
  B  B11  1  0.988  0.728  0.988  1.0
  B  B12  1  0.988  0.988  0.730  1.0
  B  B13  1  0.272  0.012  0.012  1.0
  B  B14  1  0.012  0.272  0.012  1.0
  B  B15  1  0.012  0.012  0.270  1.0
  B  B16  1  0.560  0.124  0.124  1.0
  B  B17  1  0.124  0.560  0.124  1.0
  B  B18  1  0.124  0.124  0.562  1.0
  B  B19  1  0.440  0.876  0.876  1.0
  B  B20  1  0.876  0.440  0.876  1.0
  B  B21  1  0.876  0.876  0.438  1.0
  B  B22  1  0.585  0.177  0.895  1.0
  B  B23  1  0.893  0.585  0.173  1.0
  B  B24  1  0.178  0.891  0.587  1.0
  B  B25  1  0.891  0.178  0.587  1.0
  B  B26  1  0.585  0.893  0.173  1.0
  B  B27  1  0.177  0.585  0.895  1.0
  B  B28  1  0.415  0.823  0.105  1.0
  B  B29  1  0.107  0.415  0.827  1.0
  B  B30  1  0.822  0.109  0.413  1.0
  B  B31  1  0.109  0.822  0.413  1.0
  B  B32  1  0.415  0.107  0.827  1.0
  B  B33  1  0.823  0.415  0.105  1.0
  B  B34  1  0.202  0.372  0.021  1.0
  B  B35  1  0.019  0.198  0.372  1.0
  B  B36  1  0.372  0.020  0.197  1.0
  B  B37  1  0.020  0.372  0.197  1.0
  B  B38  1  0.198  0.019  0.372  1.0
  B  B39  1  0.372  0.202  0.021  1.0
  B  B40  1  0.798  0.628  0.979  1.0
  B  B41  1  0.981  0.802  0.628  1.0
  B  B42  1  0.628  0.980  0.803  1.0
  B  B43  1  0.980  0.628  0.803  1.0
  B  B44  1  0.802  0.981  0.628  1.0
  B  B45  1  0.628  0.798  0.979  1.0
  C  C46  1  0.949  0.949  0.949  1.0
  C  C47  1  0.051  0.051  0.051  1.0
[/CIF]
.