The material described by Pr2PbSi2Se8 crystallizes in the monoclinic Cc space group. There are two inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), one Se(8), and two equivalent Se(6) atoms. In the second Pr site, Pr(2) is bonded in a 8-coordinate geometry to one Se(1), one Se(2), one Se(5), one Se(8), two equivalent Se(4), and two equivalent Se(7) atoms. Pb(1) is bonded in a 6-coordinate geometry to one Se(1), one Se(2), one Se(7), one Se(8), and two equivalent Se(3) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a tetrahedral geometry to one Se(1), one Se(3), one Se(4), and one Se(5) atom. In the second Si site, Si(2) is bonded in a tetrahedral geometry to one Se(2), one Se(6), one Se(7), and one Se(8) atom. There are eight inequivalent Se sites. In the first Se site, Se(8) is bonded in a 4-coordinate geometry to one Pr(1), one Pr(2), one Pb(1), and one Si(2) atom. In the second Se site, Se(1) is bonded in a 3-coordinate geometry to one Pr(1), one Pr(2), one Pb(1), and one Si(1) atom. In the third Se site, Se(2) is bonded in a 3-coordinate geometry to one Pr(1), one Pr(2), one Pb(1), and one Si(2) atom. In the fourth Se site, Se(3) is bonded in a 1-coordinate geometry to one Pr(1), two equivalent Pb(1), and one Si(1) atom. In the fifth Se site, Se(4) is bonded to one Pr(1), two equivalent Pr(2), and one Si(1) atom to form distorted SePr3Si trigonal pyramids that share corners with two equivalent Se(7)Pr2SiPb trigonal pyramids, corners with two equivalent Se(4)Pr3Si trigonal pyramids, and  an edgeedge with one Se(7)Pr2SiPb trigonal pyramid. In the sixth Se site, Se(5) is bonded in a distorted T-shaped geometry to one Pr(1), one Pr(2), and one Si(1) atom. In the seventh Se site, Se(6) is bonded in a T-shaped geometry to two equivalent Pr(1) and one Si(2) atom. In the eighth Se site, Se(7) is bonded to two equivalent Pr(2), one Pb(1), and one Si(2) atom to form distorted SePr2SiPb trigonal pyramids that share corners with two equivalent Se(7)Pr2SiPb trigonal pyramids, corners with two equivalent Se(4)Pr3Si trigonal pyramids, and  an edgeedge with one Se(4)Pr3Si trigonal pyramid. is represented by the CIF file [CIF]
data_Pr2Si2PbSe8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.445
_cell_length_b   9.445
_cell_length_c   10.739
_cell_angle_alpha   65.486
_cell_angle_beta   65.486
_cell_angle_gamma   60.345
_symmetry_Int_Tables_number   1
_cell_volume   730.395
_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
  Pr  Pr0  1  0.247  0.440  0.252  1.0
  Pr  Pr1  1  0.945  0.058  0.245  1.0
  Pr  Pr2  1  0.440  0.247  0.752  1.0
  Pr  Pr3  1  0.058  0.945  0.745  1.0
  Si  Si4  1  0.329  0.849  0.979  1.0
  Si  Si5  1  0.849  0.329  0.479  1.0
  Si  Si6  1  0.652  0.169  0.022  1.0
  Si  Si7  1  0.169  0.652  0.522  1.0
  Pb  Pb8  1  0.574  0.750  0.250  1.0
  Pb  Pb9  1  0.750  0.574  0.750  1.0
  Se  Se10  1  0.405  0.932  0.736  1.0
  Se  Se11  1  0.932  0.405  0.236  1.0
  Se  Se12  1  0.585  0.098  0.265  1.0
  Se  Se13  1  0.098  0.585  0.765  1.0
  Se  Se14  1  0.528  0.609  0.077  1.0
  Se  Se15  1  0.092  0.789  0.057  1.0
  Se  Se16  1  0.273  0.071  0.051  1.0
  Se  Se17  1  0.789  0.092  0.557  1.0
  Se  Se18  1  0.609  0.528  0.577  1.0
  Se  Se19  1  0.071  0.273  0.551  1.0
  Se  Se20  1  0.425  0.398  0.954  1.0
  Se  Se21  1  0.893  0.222  0.931  1.0
  Se  Se22  1  0.709  0.959  0.931  1.0
  Se  Se23  1  0.222  0.893  0.431  1.0
  Se  Se24  1  0.398  0.425  0.454  1.0
  Se  Se25  1  0.959  0.709  0.431  1.0
[/CIF]
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The material described by Pr2PbSi2Se8 crystallizes in the monoclinic Cc space group. There are two inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), one Se(8), and two equivalent Se(6) atoms. In the second Pr site, Pr(2) is bonded in a 8-coordinate geometry to one Se(1), one Se(2), one Se(5), one Se(8), two equivalent Se(4), and two equivalent Se(7) atoms. Pb(1) is bonded in a 6-coordinate geometry to one Se(1), one Se(2), one Se(7), one Se(8), and two equivalent Se(3) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a tetrahedral geometry to one Se(1), one Se(3), one Se(4), and one Se(5) atom. In the second Si site, Si(2) is bonded in a tetrahedral geometry to one Se(2), one Se(6), one Se(7), and one Se(8) atom. There are eight inequivalent Se sites. In the first Se site, Se(8) is bonded in a 4-coordinate geometry to one Pr(1), one Pr(2), one Pb(1), and one Si(2) atom. In the second Se site, Se(1) is bonded in a 3-coordinate geometry to one Pr(1), one Pr(2), one Pb(1), and one Si(1) atom. In the third Se site, Se(2) is bonded in a 3-coordinate geometry to one Pr(1), one Pr(2), one Pb(1), and one Si(2) atom. In the fourth Se site, Se(3) is bonded in a 1-coordinate geometry to one Pr(1), two equivalent Pb(1), and one Si(1) atom. In the fifth Se site, Se(4) is bonded to one Pr(1), two equivalent Pr(2), and one Si(1) atom to form distorted SePr3Si trigonal pyramids that share corners with two equivalent Se(7)Pr2SiPb trigonal pyramids, corners with two equivalent Se(4)Pr3Si trigonal pyramids, and  an edgeedge with one Se(7)Pr2SiPb trigonal pyramid. In the sixth Se site, Se(5) is bonded in a distorted T-shaped geometry to one Pr(1), one Pr(2), and one Si(1) atom. In the seventh Se site, Se(6) is bonded in a T-shaped geometry to two equivalent Pr(1) and one Si(2) atom. In the eighth Se site, Se(7) is bonded to two equivalent Pr(2), one Pb(1), and one Si(2) atom to form distorted SePr2SiPb trigonal pyramids that share corners with two equivalent Se(7)Pr2SiPb trigonal pyramids, corners with two equivalent Se(4)Pr3Si trigonal pyramids, and  an edgeedge with one Se(4)Pr3Si trigonal pyramid. is represented by the CIF file [CIF]
data_Pr2Si2PbSe8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.445
_cell_length_b   9.445
_cell_length_c   10.739
_cell_angle_alpha   65.486
_cell_angle_beta   65.486
_cell_angle_gamma   60.345
_symmetry_Int_Tables_number   1
_cell_volume   730.395
_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
  Pr  Pr0  1  0.247  0.440  0.252  1.0
  Pr  Pr1  1  0.945  0.058  0.245  1.0
  Pr  Pr2  1  0.440  0.247  0.752  1.0
  Pr  Pr3  1  0.058  0.945  0.745  1.0
  Si  Si4  1  0.329  0.849  0.979  1.0
  Si  Si5  1  0.849  0.329  0.479  1.0
  Si  Si6  1  0.652  0.169  0.022  1.0
  Si  Si7  1  0.169  0.652  0.522  1.0
  Pb  Pb8  1  0.574  0.750  0.250  1.0
  Pb  Pb9  1  0.750  0.574  0.750  1.0
  Se  Se10  1  0.405  0.932  0.736  1.0
  Se  Se11  1  0.932  0.405  0.236  1.0
  Se  Se12  1  0.585  0.098  0.265  1.0
  Se  Se13  1  0.098  0.585  0.765  1.0
  Se  Se14  1  0.528  0.609  0.077  1.0
  Se  Se15  1  0.092  0.789  0.057  1.0
  Se  Se16  1  0.273  0.071  0.051  1.0
  Se  Se17  1  0.789  0.092  0.557  1.0
  Se  Se18  1  0.609  0.528  0.577  1.0
  Se  Se19  1  0.071  0.273  0.551  1.0
  Se  Se20  1  0.425  0.398  0.954  1.0
  Se  Se21  1  0.893  0.222  0.931  1.0
  Se  Se22  1  0.709  0.959  0.931  1.0
  Se  Se23  1  0.222  0.893  0.431  1.0
  Se  Se24  1  0.398  0.425  0.454  1.0
  Se  Se25  1  0.959  0.709  0.431  1.0
[/CIF]
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