The structure described by Cs3Bi2Br9 crystallizes in the monoclinic C2/c space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to one Br(3), one Br(5), one Br(6), three equivalent Br(1), three equivalent Br(2), and three equivalent Br(4) atoms to form CsBr12 cuboctahedra that share corners with three equivalent Cs(2)Br12 cuboctahedra, corners with nine equivalent Cs(1)Br12 cuboctahedra, faces with three equivalent Cs(1)Br12 cuboctahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, and faces with five equivalent Bi(1)Br6 octahedra. In the second Cs site, Cs(2) is bonded to two equivalent Br(1), two equivalent Br(2), two equivalent Br(3), two equivalent Br(4), two equivalent Br(5), and two equivalent Br(6) atoms to form CsBr12 cuboctahedra that share corners with six equivalent Cs(1)Br12 cuboctahedra, corners with six equivalent Cs(2)Br12 cuboctahedra, faces with six equivalent Cs(1)Br12 cuboctahedra, and faces with six equivalent Bi(1)Br6 octahedra. Bi(1) is bonded to one Br(1), one Br(2), one Br(3), one Br(4), one Br(5), and one Br(6) atom to form BiBr6 octahedra that share corners with three equivalent Bi(1)Br6 octahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, and faces with five equivalent Cs(1)Br12 cuboctahedra. The corner-sharing octahedra are not tilted. There are eight inequivalent Br sites. In the first Br site, Br(6) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Bi(1) atoms to form distorted BrCs4Bi2 octahedra that share corners with two equivalent Br(3)Cs4Bi2 octahedra, corners with two equivalent Br(5)Cs4Bi2 octahedra, corners with two equivalent Br(6)Cs4Bi2 octahedra, corners with six equivalent Br(1)Cs4Bi square pyramids, faces with two equivalent Br(3)Cs4Bi2 octahedra, faces with two equivalent Br(5)Cs4Bi2 octahedra, and faces with two equivalent Br(1)Cs4Bi square pyramids. The corner-sharing octahedral tilt angles range from 0-60°. In the second Br site, Br(1) is bonded to one Cs(2), three equivalent Cs(1), and one Bi(1) atom to form distorted BrCs4Bi square pyramids that share corners with two equivalent Br(5)Cs4Bi2 octahedra; corners with three equivalent Br(3)Cs4Bi2 octahedra; corners with three Br(6,6,6)Cs4Bi2 octahedra; corners with five equivalent Br(1)Cs4Bi square pyramids; edges with two equivalent Br(5)Cs4Bi2 octahedra;  an edgeedge with one Br(1)Cs4Bi square pyramid;  a faceface with one Br(3)Cs4Bi2 octahedra; and  a faceface with one Br(6)Cs4Bi2 octahedra. The corner-sharing octahedral tilt angles range from 2-62°. In the third Br site, Br(2) is bonded in a distorted single-bond geometry to one Cs(2), three equivalent Cs(1), and one Bi(1) atom. In the fourth Br site, Br(3) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Bi(1) atoms to form distorted BrCs4Bi2 octahedra that share corners with two equivalent Br(3)Cs4Bi2 octahedra; corners with two equivalent Br(5)Cs4Bi2 octahedra; corners with two Br(6,6)Cs4Bi2 octahedra; corners with six equivalent Br(1)Cs4Bi square pyramids; faces with two equivalent Br(5)Cs4Bi2 octahedra; faces with two Br(6,6)Cs4Bi2 octahedra; and faces with two equivalent Br(1)Cs4Bi square pyramids. The corner-sharing octahedral tilt angles range from 0-60°. In the fifth Br site, Br(6) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Bi(1) atoms to form distorted BrCs4Bi2 octahedra that share corners with two equivalent Br(3)Cs4Bi2 octahedra, corners with two equivalent Br(5)Cs4Bi2 octahedra, corners with two equivalent Br(6)Cs4Bi2 octahedra, corners with six equivalent Br(1)Cs4Bi square pyramids, faces with two equivalent Br(3)Cs4Bi2 octahedra, faces with two equivalent Br(5)Cs4Bi2 octahedra, and faces with two equivalent Br(1)Cs4Bi square pyramids. The corner-sharing octahedral tilt angles range from 0-60°. In the sixth Br site, Br(4) is bonded in a distorted single-bond geometry to one Cs(2), three equivalent Cs(1), and one Bi(1) atom. In the seventh Br site, Br(5) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Bi(1) atoms to form BrCs4Bi2 octahedra that share corners with two equivalent Br(3)Cs4Bi2 octahedra; corners with two equivalent Br(5)Cs4Bi2 octahedra; corners with two Br(6,6)Cs4Bi2 octahedra; corners with four equivalent Br(1)Cs4Bi square pyramids; edges with four equivalent Br(1)Cs4Bi square pyramids; faces with two equivalent Br(3)Cs4Bi2 octahedra; and faces with two Br(6,6)Cs4Bi2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the eighth Br site, Br(6) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Bi(1) atoms to form distorted BrCs4Bi2 octahedra that share corners with two equivalent Br(3)Cs4Bi2 octahedra, corners with two equivalent Br(5)Cs4Bi2 octahedra, corners with two equivalent Br(6)Cs4Bi2 octahedra, corners with six equivalent Br(1)Cs4Bi square pyramids, faces with two equivalent Br(3)Cs4Bi2 octahedra, faces with two equivalent Br(5)Cs4Bi2 octahedra, and faces with two equivalent Br(1)Cs4Bi square pyramids. The corner-sharing octahedral tilt angles range from 0-60°. is represented by the CIF card [CIF]
data_Cs3Bi2Br9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.185
_cell_length_b   8.185
_cell_length_c   20.254
_cell_angle_alpha   89.286
_cell_angle_beta   89.286
_cell_angle_gamma   60.167
_symmetry_Int_Tables_number   1
_cell_volume   1177.048
_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
  Cs  Cs0  1  0.674  0.657  0.168  1.0
  Cs  Cs1  1  0.000  0.000  0.000  1.0
  Cs  Cs2  1  0.343  0.326  0.332  1.0
  Cs  Cs3  1  0.000  0.000  0.500  1.0
  Cs  Cs4  1  0.657  0.674  0.668  1.0
  Cs  Cs5  1  0.326  0.343  0.832  1.0
  Bi  Bi6  1  0.674  0.663  0.407  1.0
  Bi  Bi7  1  0.337  0.326  0.093  1.0
  Bi  Bi8  1  0.663  0.674  0.907  1.0
  Bi  Bi9  1  0.326  0.337  0.593  1.0
  Br  Br10  1  0.164  0.666  0.664  1.0
  Br  Br11  1  0.823  0.349  0.834  1.0
  Br  Br12  1  0.000  0.500  0.500  1.0
  Br  Br13  1  0.666  0.164  0.164  1.0
  Br  Br14  1  0.150  0.189  0.670  1.0
  Br  Br15  1  0.811  0.850  0.830  1.0
  Br  Br16  1  0.000  0.500  0.000  1.0
  Br  Br17  1  0.850  0.811  0.330  1.0
  Br  Br18  1  0.334  0.836  0.836  1.0
  Br  Br19  1  0.836  0.334  0.336  1.0
  Br  Br20  1  0.500  0.500  0.000  1.0
  Br  Br21  1  0.349  0.823  0.334  1.0
  Br  Br22  1  0.651  0.177  0.666  1.0
  Br  Br23  1  0.177  0.651  0.166  1.0
  Br  Br24  1  0.500  0.000  0.000  1.0
  Br  Br25  1  0.189  0.150  0.170  1.0
  Br  Br26  1  0.500  0.000  0.500  1.0
  Br  Br27  1  0.500  0.500  0.500  1.0
[/CIF]
.
The structure described by Cs3Bi2Br9 crystallizes in the monoclinic C2/c space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to one Br(3), one Br(5), one Br(6), three equivalent Br(1), three equivalent Br(2), and three equivalent Br(4) atoms to form CsBr12 cuboctahedra that share corners with three equivalent Cs(2)Br12 cuboctahedra, corners with nine equivalent Cs(1)Br12 cuboctahedra, faces with three equivalent Cs(1)Br12 cuboctahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, and faces with five equivalent Bi(1)Br6 octahedra. In the second Cs site, Cs(2) is bonded to two equivalent Br(1), two equivalent Br(2), two equivalent Br(3), two equivalent Br(4), two equivalent Br(5), and two equivalent Br(6) atoms to form CsBr12 cuboctahedra that share corners with six equivalent Cs(1)Br12 cuboctahedra, corners with six equivalent Cs(2)Br12 cuboctahedra, faces with six equivalent Cs(1)Br12 cuboctahedra, and faces with six equivalent Bi(1)Br6 octahedra. Bi(1) is bonded to one Br(1), one Br(2), one Br(3), one Br(4), one Br(5), and one Br(6) atom to form BiBr6 octahedra that share corners with three equivalent Bi(1)Br6 octahedra, faces with three equivalent Cs(2)Br12 cuboctahedra, and faces with five equivalent Cs(1)Br12 cuboctahedra. The corner-sharing octahedra are not tilted. There are eight inequivalent Br sites. In the first Br site, Br(6) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Bi(1) atoms to form distorted BrCs4Bi2 octahedra that share corners with two equivalent Br(3)Cs4Bi2 octahedra, corners with two equivalent Br(5)Cs4Bi2 octahedra, corners with two equivalent Br(6)Cs4Bi2 octahedra, corners with six equivalent Br(1)Cs4Bi square pyramids, faces with two equivalent Br(3)Cs4Bi2 octahedra, faces with two equivalent Br(5)Cs4Bi2 octahedra, and faces with two equivalent Br(1)Cs4Bi square pyramids. The corner-sharing octahedral tilt angles range from 0-60°. In the second Br site, Br(1) is bonded to one Cs(2), three equivalent Cs(1), and one Bi(1) atom to form distorted BrCs4Bi square pyramids that share corners with two equivalent Br(5)Cs4Bi2 octahedra; corners with three equivalent Br(3)Cs4Bi2 octahedra; corners with three Br(6,6,6)Cs4Bi2 octahedra; corners with five equivalent Br(1)Cs4Bi square pyramids; edges with two equivalent Br(5)Cs4Bi2 octahedra;  an edgeedge with one Br(1)Cs4Bi square pyramid;  a faceface with one Br(3)Cs4Bi2 octahedra; and  a faceface with one Br(6)Cs4Bi2 octahedra. The corner-sharing octahedral tilt angles range from 2-62°. In the third Br site, Br(2) is bonded in a distorted single-bond geometry to one Cs(2), three equivalent Cs(1), and one Bi(1) atom. In the fourth Br site, Br(3) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Bi(1) atoms to form distorted BrCs4Bi2 octahedra that share corners with two equivalent Br(3)Cs4Bi2 octahedra; corners with two equivalent Br(5)Cs4Bi2 octahedra; corners with two Br(6,6)Cs4Bi2 octahedra; corners with six equivalent Br(1)Cs4Bi square pyramids; faces with two equivalent Br(5)Cs4Bi2 octahedra; faces with two Br(6,6)Cs4Bi2 octahedra; and faces with two equivalent Br(1)Cs4Bi square pyramids. The corner-sharing octahedral tilt angles range from 0-60°. In the fifth Br site, Br(6) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Bi(1) atoms to form distorted BrCs4Bi2 octahedra that share corners with two equivalent Br(3)Cs4Bi2 octahedra, corners with two equivalent Br(5)Cs4Bi2 octahedra, corners with two equivalent Br(6)Cs4Bi2 octahedra, corners with six equivalent Br(1)Cs4Bi square pyramids, faces with two equivalent Br(3)Cs4Bi2 octahedra, faces with two equivalent Br(5)Cs4Bi2 octahedra, and faces with two equivalent Br(1)Cs4Bi square pyramids. The corner-sharing octahedral tilt angles range from 0-60°. In the sixth Br site, Br(4) is bonded in a distorted single-bond geometry to one Cs(2), three equivalent Cs(1), and one Bi(1) atom. In the seventh Br site, Br(5) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Bi(1) atoms to form BrCs4Bi2 octahedra that share corners with two equivalent Br(3)Cs4Bi2 octahedra; corners with two equivalent Br(5)Cs4Bi2 octahedra; corners with two Br(6,6)Cs4Bi2 octahedra; corners with four equivalent Br(1)Cs4Bi square pyramids; edges with four equivalent Br(1)Cs4Bi square pyramids; faces with two equivalent Br(3)Cs4Bi2 octahedra; and faces with two Br(6,6)Cs4Bi2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the eighth Br site, Br(6) is bonded to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Bi(1) atoms to form distorted BrCs4Bi2 octahedra that share corners with two equivalent Br(3)Cs4Bi2 octahedra, corners with two equivalent Br(5)Cs4Bi2 octahedra, corners with two equivalent Br(6)Cs4Bi2 octahedra, corners with six equivalent Br(1)Cs4Bi square pyramids, faces with two equivalent Br(3)Cs4Bi2 octahedra, faces with two equivalent Br(5)Cs4Bi2 octahedra, and faces with two equivalent Br(1)Cs4Bi square pyramids. The corner-sharing octahedral tilt angles range from 0-60°. is represented by the CIF card [CIF]
data_Cs3Bi2Br9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.185
_cell_length_b   8.185
_cell_length_c   20.254
_cell_angle_alpha   89.286
_cell_angle_beta   89.286
_cell_angle_gamma   60.167
_symmetry_Int_Tables_number   1
_cell_volume   1177.048
_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
  Cs  Cs0  1  0.674  0.657  0.168  1.0
  Cs  Cs1  1  0.000  0.000  0.000  1.0
  Cs  Cs2  1  0.343  0.326  0.332  1.0
  Cs  Cs3  1  0.000  0.000  0.500  1.0
  Cs  Cs4  1  0.657  0.674  0.668  1.0
  Cs  Cs5  1  0.326  0.343  0.832  1.0
  Bi  Bi6  1  0.674  0.663  0.407  1.0
  Bi  Bi7  1  0.337  0.326  0.093  1.0
  Bi  Bi8  1  0.663  0.674  0.907  1.0
  Bi  Bi9  1  0.326  0.337  0.593  1.0
  Br  Br10  1  0.164  0.666  0.664  1.0
  Br  Br11  1  0.823  0.349  0.834  1.0
  Br  Br12  1  0.000  0.500  0.500  1.0
  Br  Br13  1  0.666  0.164  0.164  1.0
  Br  Br14  1  0.150  0.189  0.670  1.0
  Br  Br15  1  0.811  0.850  0.830  1.0
  Br  Br16  1  0.000  0.500  0.000  1.0
  Br  Br17  1  0.850  0.811  0.330  1.0
  Br  Br18  1  0.334  0.836  0.836  1.0
  Br  Br19  1  0.836  0.334  0.336  1.0
  Br  Br20  1  0.500  0.500  0.000  1.0
  Br  Br21  1  0.349  0.823  0.334  1.0
  Br  Br22  1  0.651  0.177  0.666  1.0
  Br  Br23  1  0.177  0.651  0.166  1.0
  Br  Br24  1  0.500  0.000  0.000  1.0
  Br  Br25  1  0.189  0.150  0.170  1.0
  Br  Br26  1  0.500  0.000  0.500  1.0
  Br  Br27  1  0.500  0.500  0.500  1.0
[/CIF]
.