The crystal structure described by KCr12(Si2O7)4Br crystallizes in the tetragonal I4mm space group. The structure consists of two hydrogen bromide atoms inside a KCr12(Si2O7)4 framework. In the KCr12(Si2O7)4 framework, K(1) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(2) atoms. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a square co-planar geometry to two equivalent O(4) and two equivalent O(5) atoms. In the second Cr site, Cr(2) is bonded in a rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(4) atoms. In the third Cr site, Cr(3) is bonded in a rectangular see-saw-like geometry to two equivalent O(3) and two equivalent O(5) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), and two equivalent O(5) atoms to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), and two equivalent O(4) atoms to form corner-sharing SiO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(5) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(3), and one Si(1) atom. In the second O site, O(1) is bonded in a distorted trigonal planar geometry to one K(1), one Si(1), and one Si(2) atom. In the third O site, O(2) is bonded in a distorted trigonal planar geometry to one K(1), two equivalent Cr(2), and one Si(1) atom. In the fourth O site, O(3) is bonded in a trigonal planar geometry to two equivalent Cr(3) and one Si(2) atom. In the fifth O site, O(4) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one Si(2) atom. is represented by the CIF file [CIF]
data_KCr12Si8BrO28
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.976
_cell_length_b   9.976
_cell_length_c   9.976
_cell_angle_alpha   115.939
_cell_angle_beta   115.939
_cell_angle_gamma   97.191
_symmetry_Int_Tables_number   1
_cell_volume   738.752
_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
  K  K0  1  0.041  0.041  0.000  1.0
  Cr  Cr1  1  0.500  0.183  0.683  1.0
  Cr  Cr2  1  0.500  0.816  0.317  1.0
  Cr  Cr3  1  0.816  0.500  0.317  1.0
  Cr  Cr4  1  0.183  0.500  0.683  1.0
  Cr  Cr5  1  0.281  0.052  0.771  1.0
  Cr  Cr6  1  0.281  0.510  0.229  1.0
  Cr  Cr7  1  0.510  0.281  0.229  1.0
  Cr  Cr8  1  0.052  0.281  0.771  1.0
  Cr  Cr9  1  0.720  0.950  0.230  1.0
  Cr  Cr10  1  0.720  0.490  0.770  1.0
  Cr  Cr11  1  0.490  0.720  0.770  1.0
  Cr  Cr12  1  0.950  0.720  0.230  1.0
  Si  Si13  1  0.890  0.890  0.555  1.0
  Si  Si14  1  0.335  0.335  0.445  1.0
  Si  Si15  1  0.335  0.890  0.000  1.0
  Si  Si16  1  0.890  0.335  0.000  1.0
  Si  Si17  1  0.109  0.109  0.443  1.0
  Si  Si18  1  0.666  0.666  0.557  1.0
  Si  Si19  1  0.666  0.109  0.000  1.0
  Si  Si20  1  0.109  0.666  0.000  1.0
  Br  Br21  1  0.474  0.474  0.000  1.0
  O  O22  1  0.828  0.828  0.656  1.0
  O  O23  1  0.173  0.173  0.344  1.0
  O  O24  1  0.173  0.828  0.000  1.0
  O  O25  1  0.828  0.173  0.000  1.0
  O  O26  1  0.055  0.055  0.712  1.0
  O  O27  1  0.343  0.343  0.288  1.0
  O  O28  1  0.343  0.055  0.000  1.0
  O  O29  1  0.055  0.343  0.000  1.0
  O  O30  1  0.944  0.944  0.289  1.0
  O  O31  1  0.655  0.655  0.711  1.0
  O  O32  1  0.655  0.944  0.000  1.0
  O  O33  1  0.944  0.655  0.000  1.0
  O  O34  1  0.255  0.071  0.564  1.0
  O  O35  1  0.507  0.691  0.436  1.0
  O  O36  1  0.507  0.071  0.816  1.0
  O  O37  1  0.255  0.691  0.184  1.0
  O  O38  1  0.691  0.255  0.184  1.0
  O  O39  1  0.071  0.507  0.816  1.0
  O  O40  1  0.071  0.255  0.564  1.0
  O  O41  1  0.691  0.507  0.436  1.0
  O  O42  1  0.744  0.928  0.434  1.0
  O  O43  1  0.494  0.310  0.566  1.0
  O  O44  1  0.494  0.928  0.183  1.0
  O  O45  1  0.744  0.310  0.817  1.0
  O  O46  1  0.310  0.744  0.817  1.0
  O  O47  1  0.928  0.494  0.183  1.0
  O  O48  1  0.928  0.744  0.434  1.0
  O  O49  1  0.310  0.494  0.566  1.0
[/CIF]
.
The crystal structure described by KCr12(Si2O7)4Br crystallizes in the tetragonal I4mm space group. The structure consists of two hydrogen bromide atoms inside a KCr12(Si2O7)4 framework. In the KCr12(Si2O7)4 framework, K(1) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(2) atoms. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a square co-planar geometry to two equivalent O(4) and two equivalent O(5) atoms. In the second Cr site, Cr(2) is bonded in a rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(4) atoms. In the third Cr site, Cr(3) is bonded in a rectangular see-saw-like geometry to two equivalent O(3) and two equivalent O(5) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), and two equivalent O(5) atoms to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), and two equivalent O(4) atoms to form corner-sharing SiO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(5) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(3), and one Si(1) atom. In the second O site, O(1) is bonded in a distorted trigonal planar geometry to one K(1), one Si(1), and one Si(2) atom. In the third O site, O(2) is bonded in a distorted trigonal planar geometry to one K(1), two equivalent Cr(2), and one Si(1) atom. In the fourth O site, O(3) is bonded in a trigonal planar geometry to two equivalent Cr(3) and one Si(2) atom. In the fifth O site, O(4) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one Si(2) atom. is represented by the CIF file [CIF]
data_KCr12Si8BrO28
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.976
_cell_length_b   9.976
_cell_length_c   9.976
_cell_angle_alpha   115.939
_cell_angle_beta   115.939
_cell_angle_gamma   97.191
_symmetry_Int_Tables_number   1
_cell_volume   738.752
_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
  K  K0  1  0.041  0.041  0.000  1.0
  Cr  Cr1  1  0.500  0.183  0.683  1.0
  Cr  Cr2  1  0.500  0.816  0.317  1.0
  Cr  Cr3  1  0.816  0.500  0.317  1.0
  Cr  Cr4  1  0.183  0.500  0.683  1.0
  Cr  Cr5  1  0.281  0.052  0.771  1.0
  Cr  Cr6  1  0.281  0.510  0.229  1.0
  Cr  Cr7  1  0.510  0.281  0.229  1.0
  Cr  Cr8  1  0.052  0.281  0.771  1.0
  Cr  Cr9  1  0.720  0.950  0.230  1.0
  Cr  Cr10  1  0.720  0.490  0.770  1.0
  Cr  Cr11  1  0.490  0.720  0.770  1.0
  Cr  Cr12  1  0.950  0.720  0.230  1.0
  Si  Si13  1  0.890  0.890  0.555  1.0
  Si  Si14  1  0.335  0.335  0.445  1.0
  Si  Si15  1  0.335  0.890  0.000  1.0
  Si  Si16  1  0.890  0.335  0.000  1.0
  Si  Si17  1  0.109  0.109  0.443  1.0
  Si  Si18  1  0.666  0.666  0.557  1.0
  Si  Si19  1  0.666  0.109  0.000  1.0
  Si  Si20  1  0.109  0.666  0.000  1.0
  Br  Br21  1  0.474  0.474  0.000  1.0
  O  O22  1  0.828  0.828  0.656  1.0
  O  O23  1  0.173  0.173  0.344  1.0
  O  O24  1  0.173  0.828  0.000  1.0
  O  O25  1  0.828  0.173  0.000  1.0
  O  O26  1  0.055  0.055  0.712  1.0
  O  O27  1  0.343  0.343  0.288  1.0
  O  O28  1  0.343  0.055  0.000  1.0
  O  O29  1  0.055  0.343  0.000  1.0
  O  O30  1  0.944  0.944  0.289  1.0
  O  O31  1  0.655  0.655  0.711  1.0
  O  O32  1  0.655  0.944  0.000  1.0
  O  O33  1  0.944  0.655  0.000  1.0
  O  O34  1  0.255  0.071  0.564  1.0
  O  O35  1  0.507  0.691  0.436  1.0
  O  O36  1  0.507  0.071  0.816  1.0
  O  O37  1  0.255  0.691  0.184  1.0
  O  O38  1  0.691  0.255  0.184  1.0
  O  O39  1  0.071  0.507  0.816  1.0
  O  O40  1  0.071  0.255  0.564  1.0
  O  O41  1  0.691  0.507  0.436  1.0
  O  O42  1  0.744  0.928  0.434  1.0
  O  O43  1  0.494  0.310  0.566  1.0
  O  O44  1  0.494  0.928  0.183  1.0
  O  O45  1  0.744  0.310  0.817  1.0
  O  O46  1  0.310  0.744  0.817  1.0
  O  O47  1  0.928  0.494  0.183  1.0
  O  O48  1  0.928  0.744  0.434  1.0
  O  O49  1  0.310  0.494  0.566  1.0
[/CIF]
.