The structure described by K2Bi8Se13 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one Se(10), one Se(6), two equivalent Se(1), and three equivalent Se(7) atoms. In the second K site, K(2) is bonded in a 8-coordinate geometry to one Se(13), one Se(6), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(4) atoms. There are eight inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 5-coordinate geometry to one Se(1), two equivalent Se(13), and two equivalent Se(7) atoms. In the second Bi site, Bi(2) is bonded to one Se(3), one Se(8), two equivalent Se(2), and two equivalent Se(5) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 1-65°. In the third Bi site, Bi(3) is bonded to one Se(4), two equivalent Se(12), and three equivalent Se(8) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 52-65°. In the fourth Bi site, Bi(4) is bonded to one Se(2), two equivalent Se(13), and three equivalent Se(3) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 1-2°. In the fifth Bi site, Bi(5) is bonded to one Se(9), two equivalent Se(6), and three equivalent Se(11) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 10°. In the sixth Bi site, Bi(6) is bonded to one Se(12), one Se(6), two equivalent Se(11), and two equivalent Se(4) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 10°. In the seventh Bi site, Bi(7) is bonded to one Se(13), one Se(5), two equivalent Se(10), and two equivalent Se(3) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. In the eighth Bi site, Bi(8) is bonded in a 6-coordinate geometry to one Se(10), one Se(11), two equivalent Se(5), and two equivalent Se(9) atoms. There are thirteen inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent K(1), two equivalent K(2), and one Bi(1) atom to form SeK4Bi square pyramids that share corners with two equivalent Se(2)K2Bi3 square pyramids, corners with two equivalent Se(4)K2Bi3 trigonal bipyramids, corners with two equivalent Se(7)K3Bi2 trigonal bipyramids, corners with two equivalent Se(10)KBi3 trigonal pyramids, edges with two equivalent Se(13)KBi5 octahedra,  an edgeedge with one Se(2)K2Bi3 square pyramid, edges with two equivalent Se(1)K4Bi square pyramids,  an edgeedge with one Se(4)K2Bi3 trigonal bipyramid, and edges with three equivalent Se(7)K3Bi2 trigonal bipyramids. In the second Se site, Se(2) is bonded to two equivalent K(2), one Bi(4), and two equivalent Bi(2) atoms to form SeK2Bi3 square pyramids that share  a cornercorner with one Se(3)Bi6 octahedra, corners with two equivalent Se(1)K4Bi square pyramids, corners with two equivalent Se(4)K2Bi3 trigonal bipyramids, edges with two equivalent Se(3)Bi6 octahedra, edges with two equivalent Se(13)KBi5 octahedra,  an edgeedge with one Se(1)K4Bi square pyramid, edges with two equivalent Se(2)K2Bi3 square pyramids, and  an edgeedge with one Se(4)K2Bi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 4°. In the third Se site, Se(3) is bonded to one Bi(2), two equivalent Bi(7), and three equivalent Bi(4) atoms to form SeBi6 octahedra that share corners with two equivalent Se(13)KBi5 octahedra,  a cornercorner with one Se(2)K2Bi3 square pyramid, corners with two equivalent Se(10)KBi3 trigonal pyramids, edges with three equivalent Se(13)KBi5 octahedra, edges with four equivalent Se(3)Bi6 octahedra, edges with two equivalent Se(2)K2Bi3 square pyramids, and  an edgeedge with one Se(10)KBi3 trigonal pyramid. The corner-sharing octahedral tilt angles are 5°. In the fourth Se site, Se(4) is bonded to two equivalent K(2), one Bi(3), and two equivalent Bi(6) atoms to form distorted SeK2Bi3 trigonal bipyramids that share corners with two equivalent Se(11)Bi6 octahedra, corners with two equivalent Se(13)KBi5 octahedra, corners with two equivalent Se(2)K2Bi3 square pyramids, corners with two equivalent Se(1)K4Bi square pyramids,  an edgeedge with one Se(11)Bi6 octahedra,  an edgeedge with one Se(2)K2Bi3 square pyramid,  an edgeedge with one Se(1)K4Bi square pyramid, and edges with two equivalent Se(4)K2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-44°. In the fifth Se site, Se(5) is bonded in a 3-coordinate geometry to one Bi(7), two equivalent Bi(2), and two equivalent Bi(8) atoms. In the sixth Se site, Se(6) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Bi(6), and two equivalent Bi(5) atoms. In the seventh Se site, Se(7) is bonded to three equivalent K(1) and two equivalent Bi(1) atoms to form distorted SeK3Bi2 trigonal bipyramids that share corners with two equivalent Se(13)KBi5 octahedra, corners with two equivalent Se(1)K4Bi square pyramids, corners with three equivalent Se(10)KBi3 trigonal pyramids,  an edgeedge with one Se(13)KBi5 octahedra, edges with three equivalent Se(1)K4Bi square pyramids, and edges with four equivalent Se(7)K3Bi2 trigonal bipyramids. The corner-sharing octahedral tilt angles are 19°. In the eighth Se site, Se(8) is bonded in a rectangular see-saw-like geometry to one Bi(2) and three equivalent Bi(3) atoms. In the ninth Se site, Se(9) is bonded in a distorted trigonal non-coplanar geometry to one Bi(5) and two equivalent Bi(8) atoms. In the tenth Se site, Se(10) is bonded to one K(1), one Bi(8), and two equivalent Bi(7) atoms to form distorted SeKBi3 trigonal pyramids that share  a cornercorner with one Se(11)Bi6 octahedra, corners with two equivalent Se(3)Bi6 octahedra, corners with two equivalent Se(13)KBi5 octahedra, corners with two equivalent Se(1)K4Bi square pyramids, corners with three equivalent Se(7)K3Bi2 trigonal bipyramids, corners with two equivalent Se(10)KBi3 trigonal pyramids, and  an edgeedge with one Se(3)Bi6 octahedra. The corner-sharing octahedral tilt angles range from 6-80°. In the eleventh Se site, Se(11) is bonded to one Bi(8), two equivalent Bi(6), and three equivalent Bi(5) atoms to form SeBi6 octahedra that share corners with two equivalent Se(4)K2Bi3 trigonal bipyramids,  a cornercorner with one Se(10)KBi3 trigonal pyramid, edges with four equivalent Se(11)Bi6 octahedra, and  an edgeedge with one Se(4)K2Bi3 trigonal bipyramid. In the twelfth Se site, Se(12) is bonded in a 3-coordinate geometry to one Bi(6) and two equivalent Bi(3) atoms. In the thirteenth Se site, Se(13) is bonded to one K(2), one Bi(7), two equivalent Bi(1), and two equivalent Bi(4) atoms to form distorted SeKBi5 octahedra that share corners with two equivalent Se(3)Bi6 octahedra, corners with two equivalent Se(4)K2Bi3 trigonal bipyramids, corners with two equivalent Se(7)K3Bi2 trigonal bipyramids, corners with two equivalent Se(10)KBi3 trigonal pyramids, edges with two equivalent Se(13)KBi5 octahedra, edges with three equivalent Se(3)Bi6 octahedra, edges with two equivalent Se(2)K2Bi3 square pyramids, edges with two equivalent Se(1)K4Bi square pyramids, and  an edgeedge with one Se(7)K3Bi2 trigonal bipyramid. The corner-sharing octahedral tilt angles are 5°. is represented by the CIF card [CIF]
data_K2Bi8Se13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.247
_cell_length_b   17.784
_cell_length_c   18.834
_cell_angle_alpha   87.381
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1420.961
_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
  K  K0  1  0.250  0.490  0.852  1.0
  K  K1  1  0.750  0.510  0.148  1.0
  K  K2  1  0.250  0.751  0.770  1.0
  K  K3  1  0.750  0.249  0.230  1.0
  Bi  Bi4  1  0.750  0.668  0.967  1.0
  Bi  Bi5  1  0.250  0.332  0.033  1.0
  Bi  Bi6  1  0.750  0.985  0.254  1.0
  Bi  Bi7  1  0.250  0.015  0.746  1.0
  Bi  Bi8  1  0.250  0.107  0.483  1.0
  Bi  Bi9  1  0.750  0.893  0.517  1.0
  Bi  Bi10  1  0.250  0.079  0.070  1.0
  Bi  Bi11  1  0.750  0.921  0.930  1.0
  Bi  Bi12  1  0.250  0.508  0.400  1.0
  Bi  Bi13  1  0.750  0.492  0.600  1.0
  Bi  Bi14  1  0.750  0.307  0.451  1.0
  Bi  Bi15  1  0.250  0.693  0.549  1.0
  Bi  Bi16  1  0.250  0.826  0.129  1.0
  Bi  Bi17  1  0.750  0.174  0.871  1.0
  Bi  Bi18  1  0.750  0.722  0.320  1.0
  Bi  Bi19  1  0.250  0.278  0.680  1.0
  Se  Se20  1  0.750  0.631  0.834  1.0
  Se  Se21  1  0.250  0.369  0.166  1.0
  Se  Se22  1  0.250  0.095  0.220  1.0
  Se  Se23  1  0.750  0.905  0.780  1.0
  Se  Se24  1  0.250  0.048  0.902  1.0
  Se  Se25  1  0.750  0.952  0.098  1.0
  Se  Se26  1  0.250  0.229  0.378  1.0
  Se  Se27  1  0.750  0.771  0.622  1.0
  Se  Se28  1  0.250  0.863  0.272  1.0
  Se  Se29  1  0.750  0.137  0.728  1.0
  Se  Se30  1  0.750  0.435  0.330  1.0
  Se  Se31  1  0.250  0.565  0.670  1.0
  Se  Se32  1  0.250  0.575  0.014  1.0
  Se  Se33  1  0.750  0.425  0.986  1.0
  Se  Se34  1  0.750  0.028  0.406  1.0
  Se  Se35  1  0.250  0.972  0.594  1.0
  Se  Se36  1  0.250  0.622  0.287  1.0
  Se  Se37  1  0.750  0.378  0.713  1.0
  Se  Se38  1  0.750  0.722  0.166  1.0
  Se  Se39  1  0.250  0.278  0.834  1.0
  Se  Se40  1  0.250  0.387  0.534  1.0
  Se  Se41  1  0.750  0.613  0.466  1.0
  Se  Se42  1  0.750  0.191  0.560  1.0
  Se  Se43  1  0.250  0.809  0.440  1.0
  Se  Se44  1  0.750  0.186  0.045  1.0
  Se  Se45  1  0.250  0.814  0.955  1.0
[/CIF]
.
The structure described by K2Bi8Se13 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one Se(10), one Se(6), two equivalent Se(1), and three equivalent Se(7) atoms. In the second K site, K(2) is bonded in a 8-coordinate geometry to one Se(13), one Se(6), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(4) atoms. There are eight inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 5-coordinate geometry to one Se(1), two equivalent Se(13), and two equivalent Se(7) atoms. In the second Bi site, Bi(2) is bonded to one Se(3), one Se(8), two equivalent Se(2), and two equivalent Se(5) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 1-65°. In the third Bi site, Bi(3) is bonded to one Se(4), two equivalent Se(12), and three equivalent Se(8) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 52-65°. In the fourth Bi site, Bi(4) is bonded to one Se(2), two equivalent Se(13), and three equivalent Se(3) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 1-2°. In the fifth Bi site, Bi(5) is bonded to one Se(9), two equivalent Se(6), and three equivalent Se(11) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 10°. In the sixth Bi site, Bi(6) is bonded to one Se(12), one Se(6), two equivalent Se(11), and two equivalent Se(4) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 10°. In the seventh Bi site, Bi(7) is bonded to one Se(13), one Se(5), two equivalent Se(10), and two equivalent Se(3) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. In the eighth Bi site, Bi(8) is bonded in a 6-coordinate geometry to one Se(10), one Se(11), two equivalent Se(5), and two equivalent Se(9) atoms. There are thirteen inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent K(1), two equivalent K(2), and one Bi(1) atom to form SeK4Bi square pyramids that share corners with two equivalent Se(2)K2Bi3 square pyramids, corners with two equivalent Se(4)K2Bi3 trigonal bipyramids, corners with two equivalent Se(7)K3Bi2 trigonal bipyramids, corners with two equivalent Se(10)KBi3 trigonal pyramids, edges with two equivalent Se(13)KBi5 octahedra,  an edgeedge with one Se(2)K2Bi3 square pyramid, edges with two equivalent Se(1)K4Bi square pyramids,  an edgeedge with one Se(4)K2Bi3 trigonal bipyramid, and edges with three equivalent Se(7)K3Bi2 trigonal bipyramids. In the second Se site, Se(2) is bonded to two equivalent K(2), one Bi(4), and two equivalent Bi(2) atoms to form SeK2Bi3 square pyramids that share  a cornercorner with one Se(3)Bi6 octahedra, corners with two equivalent Se(1)K4Bi square pyramids, corners with two equivalent Se(4)K2Bi3 trigonal bipyramids, edges with two equivalent Se(3)Bi6 octahedra, edges with two equivalent Se(13)KBi5 octahedra,  an edgeedge with one Se(1)K4Bi square pyramid, edges with two equivalent Se(2)K2Bi3 square pyramids, and  an edgeedge with one Se(4)K2Bi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 4°. In the third Se site, Se(3) is bonded to one Bi(2), two equivalent Bi(7), and three equivalent Bi(4) atoms to form SeBi6 octahedra that share corners with two equivalent Se(13)KBi5 octahedra,  a cornercorner with one Se(2)K2Bi3 square pyramid, corners with two equivalent Se(10)KBi3 trigonal pyramids, edges with three equivalent Se(13)KBi5 octahedra, edges with four equivalent Se(3)Bi6 octahedra, edges with two equivalent Se(2)K2Bi3 square pyramids, and  an edgeedge with one Se(10)KBi3 trigonal pyramid. The corner-sharing octahedral tilt angles are 5°. In the fourth Se site, Se(4) is bonded to two equivalent K(2), one Bi(3), and two equivalent Bi(6) atoms to form distorted SeK2Bi3 trigonal bipyramids that share corners with two equivalent Se(11)Bi6 octahedra, corners with two equivalent Se(13)KBi5 octahedra, corners with two equivalent Se(2)K2Bi3 square pyramids, corners with two equivalent Se(1)K4Bi square pyramids,  an edgeedge with one Se(11)Bi6 octahedra,  an edgeedge with one Se(2)K2Bi3 square pyramid,  an edgeedge with one Se(1)K4Bi square pyramid, and edges with two equivalent Se(4)K2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-44°. In the fifth Se site, Se(5) is bonded in a 3-coordinate geometry to one Bi(7), two equivalent Bi(2), and two equivalent Bi(8) atoms. In the sixth Se site, Se(6) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Bi(6), and two equivalent Bi(5) atoms. In the seventh Se site, Se(7) is bonded to three equivalent K(1) and two equivalent Bi(1) atoms to form distorted SeK3Bi2 trigonal bipyramids that share corners with two equivalent Se(13)KBi5 octahedra, corners with two equivalent Se(1)K4Bi square pyramids, corners with three equivalent Se(10)KBi3 trigonal pyramids,  an edgeedge with one Se(13)KBi5 octahedra, edges with three equivalent Se(1)K4Bi square pyramids, and edges with four equivalent Se(7)K3Bi2 trigonal bipyramids. The corner-sharing octahedral tilt angles are 19°. In the eighth Se site, Se(8) is bonded in a rectangular see-saw-like geometry to one Bi(2) and three equivalent Bi(3) atoms. In the ninth Se site, Se(9) is bonded in a distorted trigonal non-coplanar geometry to one Bi(5) and two equivalent Bi(8) atoms. In the tenth Se site, Se(10) is bonded to one K(1), one Bi(8), and two equivalent Bi(7) atoms to form distorted SeKBi3 trigonal pyramids that share  a cornercorner with one Se(11)Bi6 octahedra, corners with two equivalent Se(3)Bi6 octahedra, corners with two equivalent Se(13)KBi5 octahedra, corners with two equivalent Se(1)K4Bi square pyramids, corners with three equivalent Se(7)K3Bi2 trigonal bipyramids, corners with two equivalent Se(10)KBi3 trigonal pyramids, and  an edgeedge with one Se(3)Bi6 octahedra. The corner-sharing octahedral tilt angles range from 6-80°. In the eleventh Se site, Se(11) is bonded to one Bi(8), two equivalent Bi(6), and three equivalent Bi(5) atoms to form SeBi6 octahedra that share corners with two equivalent Se(4)K2Bi3 trigonal bipyramids,  a cornercorner with one Se(10)KBi3 trigonal pyramid, edges with four equivalent Se(11)Bi6 octahedra, and  an edgeedge with one Se(4)K2Bi3 trigonal bipyramid. In the twelfth Se site, Se(12) is bonded in a 3-coordinate geometry to one Bi(6) and two equivalent Bi(3) atoms. In the thirteenth Se site, Se(13) is bonded to one K(2), one Bi(7), two equivalent Bi(1), and two equivalent Bi(4) atoms to form distorted SeKBi5 octahedra that share corners with two equivalent Se(3)Bi6 octahedra, corners with two equivalent Se(4)K2Bi3 trigonal bipyramids, corners with two equivalent Se(7)K3Bi2 trigonal bipyramids, corners with two equivalent Se(10)KBi3 trigonal pyramids, edges with two equivalent Se(13)KBi5 octahedra, edges with three equivalent Se(3)Bi6 octahedra, edges with two equivalent Se(2)K2Bi3 square pyramids, edges with two equivalent Se(1)K4Bi square pyramids, and  an edgeedge with one Se(7)K3Bi2 trigonal bipyramid. The corner-sharing octahedral tilt angles are 5°. is represented by the CIF card [CIF]
data_K2Bi8Se13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.247
_cell_length_b   17.784
_cell_length_c   18.834
_cell_angle_alpha   87.381
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1420.961
_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
  K  K0  1  0.250  0.490  0.852  1.0
  K  K1  1  0.750  0.510  0.148  1.0
  K  K2  1  0.250  0.751  0.770  1.0
  K  K3  1  0.750  0.249  0.230  1.0
  Bi  Bi4  1  0.750  0.668  0.967  1.0
  Bi  Bi5  1  0.250  0.332  0.033  1.0
  Bi  Bi6  1  0.750  0.985  0.254  1.0
  Bi  Bi7  1  0.250  0.015  0.746  1.0
  Bi  Bi8  1  0.250  0.107  0.483  1.0
  Bi  Bi9  1  0.750  0.893  0.517  1.0
  Bi  Bi10  1  0.250  0.079  0.070  1.0
  Bi  Bi11  1  0.750  0.921  0.930  1.0
  Bi  Bi12  1  0.250  0.508  0.400  1.0
  Bi  Bi13  1  0.750  0.492  0.600  1.0
  Bi  Bi14  1  0.750  0.307  0.451  1.0
  Bi  Bi15  1  0.250  0.693  0.549  1.0
  Bi  Bi16  1  0.250  0.826  0.129  1.0
  Bi  Bi17  1  0.750  0.174  0.871  1.0
  Bi  Bi18  1  0.750  0.722  0.320  1.0
  Bi  Bi19  1  0.250  0.278  0.680  1.0
  Se  Se20  1  0.750  0.631  0.834  1.0
  Se  Se21  1  0.250  0.369  0.166  1.0
  Se  Se22  1  0.250  0.095  0.220  1.0
  Se  Se23  1  0.750  0.905  0.780  1.0
  Se  Se24  1  0.250  0.048  0.902  1.0
  Se  Se25  1  0.750  0.952  0.098  1.0
  Se  Se26  1  0.250  0.229  0.378  1.0
  Se  Se27  1  0.750  0.771  0.622  1.0
  Se  Se28  1  0.250  0.863  0.272  1.0
  Se  Se29  1  0.750  0.137  0.728  1.0
  Se  Se30  1  0.750  0.435  0.330  1.0
  Se  Se31  1  0.250  0.565  0.670  1.0
  Se  Se32  1  0.250  0.575  0.014  1.0
  Se  Se33  1  0.750  0.425  0.986  1.0
  Se  Se34  1  0.750  0.028  0.406  1.0
  Se  Se35  1  0.250  0.972  0.594  1.0
  Se  Se36  1  0.250  0.622  0.287  1.0
  Se  Se37  1  0.750  0.378  0.713  1.0
  Se  Se38  1  0.750  0.722  0.166  1.0
  Se  Se39  1  0.250  0.278  0.834  1.0
  Se  Se40  1  0.250  0.387  0.534  1.0
  Se  Se41  1  0.750  0.613  0.466  1.0
  Se  Se42  1  0.750  0.191  0.560  1.0
  Se  Se43  1  0.250  0.809  0.440  1.0
  Se  Se44  1  0.750  0.186  0.045  1.0
  Se  Se45  1  0.250  0.814  0.955  1.0
[/CIF]
.