The structure described by Yb2PbSe4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Yb sites. In the first Yb site, Yb(1) is bonded to one Se(3), two equivalent Se(1), and three equivalent Se(4) atoms to form distorted YbSe6 octahedra that share corners with two equivalent Pb(1)Se5 square pyramids, corners with three equivalent Se(2)Yb2Pb2Se square pyramids, corners with four equivalent Yb(2)Se5 square pyramids, edges with four equivalent Yb(1)Se6 octahedra, and  a faceface with one Pb(1)Se5 square pyramid. In the second Yb site, Yb(2) is bonded to one Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form YbSe5 square pyramids that share corners with four equivalent Yb(1)Se6 octahedra, corners with six equivalent Pb(1)Se5 square pyramids, corners with two equivalent Se(4)Yb3Se tetrahedra,  an edgeedge with one Pb(1)Se5 square pyramid, and edges with two equivalent Yb(2)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 55-64°. Pb(1) is bonded to one Se(3), two equivalent Se(1), and two equivalent Se(2) atoms to form distorted PbSe5 square pyramids that share corners with two equivalent Yb(1)Se6 octahedra, corners with six equivalent Yb(2)Se5 square pyramids, corners with two equivalent Se(4)Yb3Se tetrahedra,  an edgeedge with one Yb(2)Se5 square pyramid, edges with two equivalent Pb(1)Se5 square pyramids, and  a faceface with one Yb(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one Yb(2), two equivalent Yb(1), and two equivalent Pb(1) atoms. In the second Se site, Se(2) is bonded to two equivalent Yb(2), two equivalent Pb(1), and one Se(4) atom to form distorted SeYb2Pb2Se square pyramids that share corners with three equivalent Yb(1)Se6 octahedra and edges with two equivalent Se(2)Yb2Pb2Se square pyramids. The corner-sharing octahedral tilt angles range from 58-66°. In the third Se site, Se(3) is bonded in a 4-coordinate geometry to one Yb(1), two equivalent Yb(2), and one Pb(1) atom. In the fourth Se site, Se(4) is bonded to three equivalent Yb(1) and one Se(2) atom to form distorted SeYb3Se tetrahedra that share corners with two equivalent Yb(2)Se5 square pyramids, corners with two equivalent Pb(1)Se5 square pyramids, corners with two equivalent Se(4)Yb3Se tetrahedra, and edges with two equivalent Se(4)Yb3Se tetrahedra. is represented by the CIF file [CIF]
data_Yb2PbSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.359
_cell_length_b   12.291
_cell_length_c   15.652
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   838.678
_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
  Yb  Yb0  1  0.750  0.008  0.130  1.0
  Yb  Yb1  1  0.750  0.508  0.370  1.0
  Yb  Yb2  1  0.250  0.992  0.870  1.0
  Yb  Yb3  1  0.250  0.492  0.630  1.0
  Yb  Yb4  1  0.750  0.141  0.592  1.0
  Yb  Yb5  1  0.750  0.641  0.908  1.0
  Yb  Yb6  1  0.250  0.859  0.408  1.0
  Yb  Yb7  1  0.250  0.359  0.092  1.0
  Pb  Pb8  1  0.750  0.685  0.189  1.0
  Pb  Pb9  1  0.750  0.185  0.311  1.0
  Pb  Pb10  1  0.250  0.315  0.811  1.0
  Pb  Pb11  1  0.250  0.815  0.689  1.0
  Se  Se12  1  0.750  0.342  0.676  1.0
  Se  Se13  1  0.750  0.842  0.824  1.0
  Se  Se14  1  0.250  0.658  0.324  1.0
  Se  Se15  1  0.250  0.158  0.176  1.0
  Se  Se16  1  0.750  0.312  0.959  1.0
  Se  Se17  1  0.750  0.812  0.541  1.0
  Se  Se18  1  0.250  0.688  0.041  1.0
  Se  Se19  1  0.250  0.188  0.459  1.0
  Se  Se20  1  0.750  0.456  0.183  1.0
  Se  Se21  1  0.750  0.956  0.317  1.0
  Se  Se22  1  0.250  0.544  0.817  1.0
  Se  Se23  1  0.250  0.044  0.683  1.0
  Se  Se24  1  0.750  0.116  0.955  1.0
  Se  Se25  1  0.750  0.616  0.545  1.0
  Se  Se26  1  0.250  0.884  0.045  1.0
  Se  Se27  1  0.250  0.384  0.455  1.0
[/CIF]
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The structure described by Yb2PbSe4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Yb sites. In the first Yb site, Yb(1) is bonded to one Se(3), two equivalent Se(1), and three equivalent Se(4) atoms to form distorted YbSe6 octahedra that share corners with two equivalent Pb(1)Se5 square pyramids, corners with three equivalent Se(2)Yb2Pb2Se square pyramids, corners with four equivalent Yb(2)Se5 square pyramids, edges with four equivalent Yb(1)Se6 octahedra, and  a faceface with one Pb(1)Se5 square pyramid. In the second Yb site, Yb(2) is bonded to one Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form YbSe5 square pyramids that share corners with four equivalent Yb(1)Se6 octahedra, corners with six equivalent Pb(1)Se5 square pyramids, corners with two equivalent Se(4)Yb3Se tetrahedra,  an edgeedge with one Pb(1)Se5 square pyramid, and edges with two equivalent Yb(2)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 55-64°. Pb(1) is bonded to one Se(3), two equivalent Se(1), and two equivalent Se(2) atoms to form distorted PbSe5 square pyramids that share corners with two equivalent Yb(1)Se6 octahedra, corners with six equivalent Yb(2)Se5 square pyramids, corners with two equivalent Se(4)Yb3Se tetrahedra,  an edgeedge with one Yb(2)Se5 square pyramid, edges with two equivalent Pb(1)Se5 square pyramids, and  a faceface with one Yb(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one Yb(2), two equivalent Yb(1), and two equivalent Pb(1) atoms. In the second Se site, Se(2) is bonded to two equivalent Yb(2), two equivalent Pb(1), and one Se(4) atom to form distorted SeYb2Pb2Se square pyramids that share corners with three equivalent Yb(1)Se6 octahedra and edges with two equivalent Se(2)Yb2Pb2Se square pyramids. The corner-sharing octahedral tilt angles range from 58-66°. In the third Se site, Se(3) is bonded in a 4-coordinate geometry to one Yb(1), two equivalent Yb(2), and one Pb(1) atom. In the fourth Se site, Se(4) is bonded to three equivalent Yb(1) and one Se(2) atom to form distorted SeYb3Se tetrahedra that share corners with two equivalent Yb(2)Se5 square pyramids, corners with two equivalent Pb(1)Se5 square pyramids, corners with two equivalent Se(4)Yb3Se tetrahedra, and edges with two equivalent Se(4)Yb3Se tetrahedra. is represented by the CIF file [CIF]
data_Yb2PbSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.359
_cell_length_b   12.291
_cell_length_c   15.652
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   838.678
_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
  Yb  Yb0  1  0.750  0.008  0.130  1.0
  Yb  Yb1  1  0.750  0.508  0.370  1.0
  Yb  Yb2  1  0.250  0.992  0.870  1.0
  Yb  Yb3  1  0.250  0.492  0.630  1.0
  Yb  Yb4  1  0.750  0.141  0.592  1.0
  Yb  Yb5  1  0.750  0.641  0.908  1.0
  Yb  Yb6  1  0.250  0.859  0.408  1.0
  Yb  Yb7  1  0.250  0.359  0.092  1.0
  Pb  Pb8  1  0.750  0.685  0.189  1.0
  Pb  Pb9  1  0.750  0.185  0.311  1.0
  Pb  Pb10  1  0.250  0.315  0.811  1.0
  Pb  Pb11  1  0.250  0.815  0.689  1.0
  Se  Se12  1  0.750  0.342  0.676  1.0
  Se  Se13  1  0.750  0.842  0.824  1.0
  Se  Se14  1  0.250  0.658  0.324  1.0
  Se  Se15  1  0.250  0.158  0.176  1.0
  Se  Se16  1  0.750  0.312  0.959  1.0
  Se  Se17  1  0.750  0.812  0.541  1.0
  Se  Se18  1  0.250  0.688  0.041  1.0
  Se  Se19  1  0.250  0.188  0.459  1.0
  Se  Se20  1  0.750  0.456  0.183  1.0
  Se  Se21  1  0.750  0.956  0.317  1.0
  Se  Se22  1  0.250  0.544  0.817  1.0
  Se  Se23  1  0.250  0.044  0.683  1.0
  Se  Se24  1  0.750  0.116  0.955  1.0
  Se  Se25  1  0.750  0.616  0.545  1.0
  Se  Se26  1  0.250  0.884  0.045  1.0
  Se  Se27  1  0.250  0.384  0.455  1.0
[/CIF]
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