The crystal structure described by Pr4Ag2Se7 crystallizes in the monoclinic Pc space group. There are four inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), one Se(4), one Se(5), one Se(6), one Se(7), and two equivalent Se(1) atoms. In the second Pr site, Pr(2) is bonded in a 8-coordinate geometry to one Se(4), one Se(7), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms. In the third Pr site, Pr(3) is bonded in a 8-coordinate geometry to one Se(2), one Se(4), one Se(5), one Se(7), two equivalent Se(1), and two equivalent Se(3) atoms. In the fourth Pr site, Pr(4) is bonded in a 6-coordinate geometry to one Se(2), one Se(4), one Se(5), one Se(7), and two equivalent Se(6) atoms. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded in a 6-coordinate geometry to one Se(2), one Se(3), one Se(4), one Se(5), one Se(6), and one Se(7) atom. In the second Ag site, Ag(2) is bonded in a 6-coordinate geometry to one Se(4), one Se(7), two equivalent Se(5), and two equivalent Se(6) atoms. There are seven inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to two equivalent Pr(1), two equivalent Pr(2), and two equivalent Pr(3) atoms. In the second Se site, Se(2) is bonded to one Pr(1), one Pr(3), one Pr(4), two equivalent Pr(2), and one Ag(1) atom to form distorted SePr5Ag octahedra that share corners with two equivalent Se(7)Pr4Ag2 octahedra, corners with two equivalent Se(2)Pr5Ag octahedra, corners with three equivalent Se(4)Pr4Ag2 octahedra, edges with two equivalent Se(5)Pr3Ag3 octahedra, edges with two equivalent Se(7)Pr4Ag2 octahedra, and  a faceface with one Se(4)Pr4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 15-49°. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Pr(1), two equivalent Pr(2), two equivalent Pr(3), and one Ag(1) atom. In the fourth Se site, Se(4) is bonded to one Pr(1), one Pr(2), one Pr(3), one Pr(4), one Ag(1), and one Ag(2) atom to form distorted SePr4Ag2 octahedra that share corners with two equivalent Se(5)Pr3Ag3 octahedra, corners with three equivalent Se(2)Pr5Ag octahedra, edges with two equivalent Se(5)Pr3Ag3 octahedra,  a faceface with one Se(2)Pr5Ag octahedra, and faces with two equivalent Se(7)Pr4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 15-64°. In the fifth Se site, Se(5) is bonded to one Pr(1), one Pr(3), one Pr(4), one Ag(1), and two equivalent Ag(2) atoms to form distorted SePr3Ag3 octahedra that share corners with two equivalent Se(5)Pr3Ag3 octahedra, corners with two equivalent Se(4)Pr4Ag2 octahedra, corners with three equivalent Se(7)Pr4Ag2 octahedra, edges with two equivalent Se(4)Pr4Ag2 octahedra, edges with two equivalent Se(2)Pr5Ag octahedra, and  a faceface with one Se(7)Pr4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 15-64°. In the sixth Se site, Se(6) is bonded in a 6-coordinate geometry to one Pr(1), two equivalent Pr(4), one Ag(1), and two equivalent Ag(2) atoms. In the seventh Se site, Se(7) is bonded to one Pr(1), one Pr(2), one Pr(3), one Pr(4), one Ag(1), and one Ag(2) atom to form distorted SePr4Ag2 octahedra that share corners with two equivalent Se(2)Pr5Ag octahedra, corners with three equivalent Se(5)Pr3Ag3 octahedra, edges with two equivalent Se(2)Pr5Ag octahedra,  a faceface with one Se(5)Pr3Ag3 octahedra, and faces with two equivalent Se(4)Pr4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 15-49°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Pr4Ag2Se7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.389
_cell_length_b   7.564
_cell_length_c   7.885
_cell_angle_alpha   71.096
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   699.019
_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  0.204  0.176  0.201  1.0
  Pr  Pr1  1  0.938  0.557  0.053  1.0
  Pr  Pr2  1  0.062  0.557  0.553  1.0
  Pr  Pr3  1  0.796  0.176  0.701  1.0
  Pr  Pr4  1  0.851  0.986  0.260  1.0
  Pr  Pr5  1  0.149  0.986  0.760  1.0
  Pr  Pr6  1  0.372  0.484  0.752  1.0
  Pr  Pr7  1  0.628  0.484  0.252  1.0
  Ag  Ag8  1  0.685  0.690  0.681  1.0
  Ag  Ag9  1  0.442  0.093  0.551  1.0
  Ag  Ag10  1  0.558  0.093  0.051  1.0
  Ag  Ag11  1  0.315  0.690  0.181  1.0
  Se  Se12  1  0.004  0.238  0.387  1.0
  Se  Se13  1  0.169  0.564  0.918  1.0
  Se  Se14  1  0.932  0.829  0.681  1.0
  Se  Se15  1  0.831  0.564  0.418  1.0
  Se  Se16  1  0.710  0.849  0.003  1.0
  Se  Se17  1  0.068  0.829  0.181  1.0
  Se  Se18  1  0.651  0.043  0.453  1.0
  Se  Se19  1  0.422  0.398  0.136  1.0
  Se  Se20  1  0.349  0.043  0.953  1.0
  Se  Se21  1  0.253  0.342  0.507  1.0
  Se  Se22  1  0.996  0.238  0.887  1.0
  Se  Se23  1  0.578  0.398  0.636  1.0
  Se  Se24  1  0.747  0.342  0.007  1.0
  Se  Se25  1  0.290  0.849  0.503  1.0
[/CIF]
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The crystal structure described by Pr4Ag2Se7 crystallizes in the monoclinic Pc space group. There are four inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), one Se(4), one Se(5), one Se(6), one Se(7), and two equivalent Se(1) atoms. In the second Pr site, Pr(2) is bonded in a 8-coordinate geometry to one Se(4), one Se(7), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms. In the third Pr site, Pr(3) is bonded in a 8-coordinate geometry to one Se(2), one Se(4), one Se(5), one Se(7), two equivalent Se(1), and two equivalent Se(3) atoms. In the fourth Pr site, Pr(4) is bonded in a 6-coordinate geometry to one Se(2), one Se(4), one Se(5), one Se(7), and two equivalent Se(6) atoms. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded in a 6-coordinate geometry to one Se(2), one Se(3), one Se(4), one Se(5), one Se(6), and one Se(7) atom. In the second Ag site, Ag(2) is bonded in a 6-coordinate geometry to one Se(4), one Se(7), two equivalent Se(5), and two equivalent Se(6) atoms. There are seven inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to two equivalent Pr(1), two equivalent Pr(2), and two equivalent Pr(3) atoms. In the second Se site, Se(2) is bonded to one Pr(1), one Pr(3), one Pr(4), two equivalent Pr(2), and one Ag(1) atom to form distorted SePr5Ag octahedra that share corners with two equivalent Se(7)Pr4Ag2 octahedra, corners with two equivalent Se(2)Pr5Ag octahedra, corners with three equivalent Se(4)Pr4Ag2 octahedra, edges with two equivalent Se(5)Pr3Ag3 octahedra, edges with two equivalent Se(7)Pr4Ag2 octahedra, and  a faceface with one Se(4)Pr4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 15-49°. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Pr(1), two equivalent Pr(2), two equivalent Pr(3), and one Ag(1) atom. In the fourth Se site, Se(4) is bonded to one Pr(1), one Pr(2), one Pr(3), one Pr(4), one Ag(1), and one Ag(2) atom to form distorted SePr4Ag2 octahedra that share corners with two equivalent Se(5)Pr3Ag3 octahedra, corners with three equivalent Se(2)Pr5Ag octahedra, edges with two equivalent Se(5)Pr3Ag3 octahedra,  a faceface with one Se(2)Pr5Ag octahedra, and faces with two equivalent Se(7)Pr4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 15-64°. In the fifth Se site, Se(5) is bonded to one Pr(1), one Pr(3), one Pr(4), one Ag(1), and two equivalent Ag(2) atoms to form distorted SePr3Ag3 octahedra that share corners with two equivalent Se(5)Pr3Ag3 octahedra, corners with two equivalent Se(4)Pr4Ag2 octahedra, corners with three equivalent Se(7)Pr4Ag2 octahedra, edges with two equivalent Se(4)Pr4Ag2 octahedra, edges with two equivalent Se(2)Pr5Ag octahedra, and  a faceface with one Se(7)Pr4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 15-64°. In the sixth Se site, Se(6) is bonded in a 6-coordinate geometry to one Pr(1), two equivalent Pr(4), one Ag(1), and two equivalent Ag(2) atoms. In the seventh Se site, Se(7) is bonded to one Pr(1), one Pr(2), one Pr(3), one Pr(4), one Ag(1), and one Ag(2) atom to form distorted SePr4Ag2 octahedra that share corners with two equivalent Se(2)Pr5Ag octahedra, corners with three equivalent Se(5)Pr3Ag3 octahedra, edges with two equivalent Se(2)Pr5Ag octahedra,  a faceface with one Se(5)Pr3Ag3 octahedra, and faces with two equivalent Se(4)Pr4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 15-49°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Pr4Ag2Se7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.389
_cell_length_b   7.564
_cell_length_c   7.885
_cell_angle_alpha   71.096
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   699.019
_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  0.204  0.176  0.201  1.0
  Pr  Pr1  1  0.938  0.557  0.053  1.0
  Pr  Pr2  1  0.062  0.557  0.553  1.0
  Pr  Pr3  1  0.796  0.176  0.701  1.0
  Pr  Pr4  1  0.851  0.986  0.260  1.0
  Pr  Pr5  1  0.149  0.986  0.760  1.0
  Pr  Pr6  1  0.372  0.484  0.752  1.0
  Pr  Pr7  1  0.628  0.484  0.252  1.0
  Ag  Ag8  1  0.685  0.690  0.681  1.0
  Ag  Ag9  1  0.442  0.093  0.551  1.0
  Ag  Ag10  1  0.558  0.093  0.051  1.0
  Ag  Ag11  1  0.315  0.690  0.181  1.0
  Se  Se12  1  0.004  0.238  0.387  1.0
  Se  Se13  1  0.169  0.564  0.918  1.0
  Se  Se14  1  0.932  0.829  0.681  1.0
  Se  Se15  1  0.831  0.564  0.418  1.0
  Se  Se16  1  0.710  0.849  0.003  1.0
  Se  Se17  1  0.068  0.829  0.181  1.0
  Se  Se18  1  0.651  0.043  0.453  1.0
  Se  Se19  1  0.422  0.398  0.136  1.0
  Se  Se20  1  0.349  0.043  0.953  1.0
  Se  Se21  1  0.253  0.342  0.507  1.0
  Se  Se22  1  0.996  0.238  0.887  1.0
  Se  Se23  1  0.578  0.398  0.636  1.0
  Se  Se24  1  0.747  0.342  0.007  1.0
  Se  Se25  1  0.290  0.849  0.503  1.0
[/CIF]
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