The compound described by Cu4Bi7S12 crystallizes in the monoclinic C2/m space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form CuS4 tetrahedra that share corners with four equivalent Bi(3)S5 square pyramids, corners with two equivalent Cu(1)S4 tetrahedra, and  an edgeedge with one Cu(1)S4 tetrahedra. In the second Cu site, Cu(2) is bonded in a trigonal planar geometry to one S(3), one S(5), and two equivalent S(6) atoms. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to two equivalent S(6) and four equivalent S(5) atoms to form BiS6 octahedra that share corners with two equivalent Bi(4)S6 octahedra, corners with four equivalent Bi(3)S5 square pyramids, edges with two equivalent Bi(1)S6 octahedra, edges with four equivalent Bi(4)S6 octahedra, and edges with two equivalent Bi(3)S5 square pyramids. The corner-sharing octahedral tilt angles are 10°. In the second Bi site, Bi(2) is bonded in a 5-coordinate geometry to two equivalent S(3) and three equivalent S(1) atoms. In the third Bi site, Bi(3) is bonded to one S(4), two equivalent S(2), and two equivalent S(5) atoms to form BiS5 square pyramids that share corners with two equivalent Bi(1)S6 octahedra, corners with four equivalent Cu(1)S4 tetrahedra,  an edgeedge with one Bi(1)S6 octahedra, edges with two equivalent Bi(4)S6 octahedra, and edges with two equivalent Bi(3)S5 square pyramids. The corner-sharing octahedral tilt angles are 11°. In the fourth Bi site, Bi(4) is bonded to one S(5), two equivalent S(4), and three equivalent S(6) atoms to form BiS6 octahedra that share  a cornercorner with one Bi(1)S6 octahedra, edges with two equivalent Bi(1)S6 octahedra, edges with four equivalent Bi(4)S6 octahedra, and edges with two equivalent Bi(3)S5 square pyramids. The corner-sharing octahedral tilt angles are 10°. There are six inequivalent S sites. In the first S site, S(6) is bonded to two equivalent Cu(2), one Bi(1), and three equivalent Bi(4) atoms to form a mixture of distorted corner and edge-sharing SCu2Bi4 octahedra. The corner-sharing octahedra are not tilted. In the second S site, S(1) is bonded in a 5-coordinate geometry to two equivalent Cu(1) and three equivalent Bi(2) atoms. In the third S site, S(2) is bonded to two equivalent Cu(1) and two equivalent Bi(3) atoms to form a mixture of corner and edge-sharing SCu2Bi2 trigonal pyramids. In the fourth S site, S(3) is bonded in a trigonal non-coplanar geometry to one Cu(2) and two equivalent Bi(2) atoms. In the fifth S site, S(4) is bonded in a distorted trigonal non-coplanar geometry to one Bi(3) and two equivalent Bi(4) atoms. In the sixth S site, S(5) is bonded in a 6-coordinate geometry to one Cu(2), one Bi(4), two equivalent Bi(1), and two equivalent Bi(3) atoms. is represented by the CIF card [CIF]
data_Cu4Bi7S12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.444
_cell_length_b   9.444
_cell_length_c   15.223
_cell_angle_alpha   77.793
_cell_angle_beta   77.793
_cell_angle_gamma   24.112
_symmetry_Int_Tables_number   1
_cell_volume   541.528
_cell_formula_units_Z   1
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
  Cu  Cu0  1  0.592  0.592  0.010  1.0
  Cu  Cu1  1  0.408  0.408  0.990  1.0
  Cu  Cu2  1  0.653  0.653  0.361  1.0
  Cu  Cu3  1  0.347  0.347  0.639  1.0
  Bi  Bi4  1  0.000  0.000  0.500  1.0
  Bi  Bi5  1  0.238  0.238  0.129  1.0
  Bi  Bi6  1  0.762  0.762  0.871  1.0
  Bi  Bi7  1  0.992  0.992  0.220  1.0
  Bi  Bi8  1  0.008  0.008  0.780  1.0
  Bi  Bi9  1  0.329  0.329  0.411  1.0
  Bi  Bi10  1  0.671  0.671  0.589  1.0
  S  S11  1  0.161  0.161  0.002  1.0
  S  S12  1  0.839  0.839  0.998  1.0
  S  S13  1  0.475  0.475  0.107  1.0
  S  S14  1  0.525  0.525  0.893  1.0
  S  S15  1  0.649  0.649  0.216  1.0
  S  S16  1  0.351  0.351  0.784  1.0
  S  S17  1  0.843  0.843  0.283  1.0
  S  S18  1  0.157  0.157  0.717  1.0
  S  S19  1  0.483  0.483  0.376  1.0
  S  S20  1  0.517  0.517  0.624  1.0
  S  S21  1  0.160  0.160  0.439  1.0
  S  S22  1  0.840  0.840  0.561  1.0
[/CIF]
.
The compound described by Cu4Bi7S12 crystallizes in the monoclinic C2/m space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form CuS4 tetrahedra that share corners with four equivalent Bi(3)S5 square pyramids, corners with two equivalent Cu(1)S4 tetrahedra, and  an edgeedge with one Cu(1)S4 tetrahedra. In the second Cu site, Cu(2) is bonded in a trigonal planar geometry to one S(3), one S(5), and two equivalent S(6) atoms. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to two equivalent S(6) and four equivalent S(5) atoms to form BiS6 octahedra that share corners with two equivalent Bi(4)S6 octahedra, corners with four equivalent Bi(3)S5 square pyramids, edges with two equivalent Bi(1)S6 octahedra, edges with four equivalent Bi(4)S6 octahedra, and edges with two equivalent Bi(3)S5 square pyramids. The corner-sharing octahedral tilt angles are 10°. In the second Bi site, Bi(2) is bonded in a 5-coordinate geometry to two equivalent S(3) and three equivalent S(1) atoms. In the third Bi site, Bi(3) is bonded to one S(4), two equivalent S(2), and two equivalent S(5) atoms to form BiS5 square pyramids that share corners with two equivalent Bi(1)S6 octahedra, corners with four equivalent Cu(1)S4 tetrahedra,  an edgeedge with one Bi(1)S6 octahedra, edges with two equivalent Bi(4)S6 octahedra, and edges with two equivalent Bi(3)S5 square pyramids. The corner-sharing octahedral tilt angles are 11°. In the fourth Bi site, Bi(4) is bonded to one S(5), two equivalent S(4), and three equivalent S(6) atoms to form BiS6 octahedra that share  a cornercorner with one Bi(1)S6 octahedra, edges with two equivalent Bi(1)S6 octahedra, edges with four equivalent Bi(4)S6 octahedra, and edges with two equivalent Bi(3)S5 square pyramids. The corner-sharing octahedral tilt angles are 10°. There are six inequivalent S sites. In the first S site, S(6) is bonded to two equivalent Cu(2), one Bi(1), and three equivalent Bi(4) atoms to form a mixture of distorted corner and edge-sharing SCu2Bi4 octahedra. The corner-sharing octahedra are not tilted. In the second S site, S(1) is bonded in a 5-coordinate geometry to two equivalent Cu(1) and three equivalent Bi(2) atoms. In the third S site, S(2) is bonded to two equivalent Cu(1) and two equivalent Bi(3) atoms to form a mixture of corner and edge-sharing SCu2Bi2 trigonal pyramids. In the fourth S site, S(3) is bonded in a trigonal non-coplanar geometry to one Cu(2) and two equivalent Bi(2) atoms. In the fifth S site, S(4) is bonded in a distorted trigonal non-coplanar geometry to one Bi(3) and two equivalent Bi(4) atoms. In the sixth S site, S(5) is bonded in a 6-coordinate geometry to one Cu(2), one Bi(4), two equivalent Bi(1), and two equivalent Bi(3) atoms. is represented by the CIF card [CIF]
data_Cu4Bi7S12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.444
_cell_length_b   9.444
_cell_length_c   15.223
_cell_angle_alpha   77.793
_cell_angle_beta   77.793
_cell_angle_gamma   24.112
_symmetry_Int_Tables_number   1
_cell_volume   541.528
_cell_formula_units_Z   1
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
  Cu  Cu0  1  0.592  0.592  0.010  1.0
  Cu  Cu1  1  0.408  0.408  0.990  1.0
  Cu  Cu2  1  0.653  0.653  0.361  1.0
  Cu  Cu3  1  0.347  0.347  0.639  1.0
  Bi  Bi4  1  0.000  0.000  0.500  1.0
  Bi  Bi5  1  0.238  0.238  0.129  1.0
  Bi  Bi6  1  0.762  0.762  0.871  1.0
  Bi  Bi7  1  0.992  0.992  0.220  1.0
  Bi  Bi8  1  0.008  0.008  0.780  1.0
  Bi  Bi9  1  0.329  0.329  0.411  1.0
  Bi  Bi10  1  0.671  0.671  0.589  1.0
  S  S11  1  0.161  0.161  0.002  1.0
  S  S12  1  0.839  0.839  0.998  1.0
  S  S13  1  0.475  0.475  0.107  1.0
  S  S14  1  0.525  0.525  0.893  1.0
  S  S15  1  0.649  0.649  0.216  1.0
  S  S16  1  0.351  0.351  0.784  1.0
  S  S17  1  0.843  0.843  0.283  1.0
  S  S18  1  0.157  0.157  0.717  1.0
  S  S19  1  0.483  0.483  0.376  1.0
  S  S20  1  0.517  0.517  0.624  1.0
  S  S21  1  0.160  0.160  0.439  1.0
  S  S22  1  0.840  0.840  0.561  1.0
[/CIF]
.