The crystal structure described by BaSr2I6 is Baddeleyite-derived structured and crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded to one I(1), one I(2), one I(4), one I(5), one I(6), and two equivalent I(3) atoms to form distorted BaI7 pentagonal bipyramids that share corners with four equivalent Sr(2)I7 pentagonal bipyramids,  an edgeedge with one Ba(1)I7 pentagonal bipyramid, and edges with two equivalent Sr(2)I7 pentagonal bipyramids. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one I(5), two equivalent I(1), two equivalent I(2), and two equivalent I(6) atoms. In the second Sr site, Sr(2) is bonded to one I(1), one I(2), one I(3), one I(5), one I(6), and two equivalent I(4) atoms to form distorted SrI7 pentagonal bipyramids that share corners with four equivalent Ba(1)I7 pentagonal bipyramids,  an edgeedge with one Sr(2)I7 pentagonal bipyramid, and edges with two equivalent Ba(1)I7 pentagonal bipyramids. There are six inequivalent I sites. In the first I site, I(1) is bonded to one Ba(1), one Sr(2), and two equivalent Sr(1) atoms to form a mixture of corner and edge-sharing IBaSr3 tetrahedra. In the second I site, I(2) is bonded in a 4-coordinate geometry to one Ba(1), one Sr(2), and two equivalent Sr(1) atoms. In the third I site, I(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ba(1) and one Sr(2) atom. In the fourth I site, I(4) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1) and two equivalent Sr(2) atoms. In the fifth I site, I(5) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Sr(1), and one Sr(2) atom. In the sixth I site, I(6) is bonded to one Ba(1), one Sr(2), and two equivalent Sr(1) atoms to form a mixture of distorted corner and edge-sharing IBaSr3 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_BaSr2I6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.280
_cell_length_b   8.503
_cell_length_c   24.789
_cell_angle_alpha   87.572
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1743.698
_cell_formula_units_Z   4
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
  Ba  Ba0  1  0.961  0.833  0.594  1.0
  Ba  Ba1  1  0.539  0.833  0.094  1.0
  Ba  Ba2  1  0.461  0.167  0.906  1.0
  Ba  Ba3  1  0.039  0.167  0.406  1.0
  Sr  Sr4  1  0.462  0.768  0.743  1.0
  Sr  Sr5  1  0.030  0.662  0.907  1.0
  Sr  Sr6  1  0.038  0.768  0.243  1.0
  Sr  Sr7  1  0.470  0.662  0.407  1.0
  Sr  Sr8  1  0.530  0.338  0.593  1.0
  Sr  Sr9  1  0.962  0.232  0.757  1.0
  Sr  Sr10  1  0.970  0.338  0.093  1.0
  Sr  Sr11  1  0.538  0.232  0.257  1.0
  I  I12  1  0.195  0.955  0.820  1.0
  I  I13  1  0.714  0.896  0.840  1.0
  I  I14  1  0.286  0.861  0.982  1.0
  I  I15  1  0.305  0.955  0.320  1.0
  I  I16  1  0.786  0.896  0.340  1.0
  I  I17  1  0.214  0.861  0.482  1.0
  I  I18  1  0.694  0.632  0.517  1.0
  I  I19  1  0.273  0.596  0.646  1.0
  I  I20  1  0.761  0.535  0.687  1.0
  I  I21  1  0.261  0.465  0.813  1.0
  I  I22  1  0.806  0.632  0.017  1.0
  I  I23  1  0.773  0.404  0.854  1.0
  I  I24  1  0.227  0.596  0.146  1.0
  I  I25  1  0.194  0.368  0.983  1.0
  I  I26  1  0.739  0.535  0.187  1.0
  I  I27  1  0.239  0.465  0.313  1.0
  I  I28  1  0.727  0.404  0.354  1.0
  I  I29  1  0.306  0.368  0.483  1.0
  I  I30  1  0.786  0.139  0.518  1.0
  I  I31  1  0.214  0.104  0.660  1.0
  I  I32  1  0.695  0.045  0.680  1.0
  I  I33  1  0.714  0.139  0.018  1.0
  I  I34  1  0.286  0.104  0.160  1.0
  I  I35  1  0.805  0.045  0.180  1.0
[/CIF]
.
The crystal structure described by BaSr2I6 is Baddeleyite-derived structured and crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded to one I(1), one I(2), one I(4), one I(5), one I(6), and two equivalent I(3) atoms to form distorted BaI7 pentagonal bipyramids that share corners with four equivalent Sr(2)I7 pentagonal bipyramids,  an edgeedge with one Ba(1)I7 pentagonal bipyramid, and edges with two equivalent Sr(2)I7 pentagonal bipyramids. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one I(5), two equivalent I(1), two equivalent I(2), and two equivalent I(6) atoms. In the second Sr site, Sr(2) is bonded to one I(1), one I(2), one I(3), one I(5), one I(6), and two equivalent I(4) atoms to form distorted SrI7 pentagonal bipyramids that share corners with four equivalent Ba(1)I7 pentagonal bipyramids,  an edgeedge with one Sr(2)I7 pentagonal bipyramid, and edges with two equivalent Ba(1)I7 pentagonal bipyramids. There are six inequivalent I sites. In the first I site, I(1) is bonded to one Ba(1), one Sr(2), and two equivalent Sr(1) atoms to form a mixture of corner and edge-sharing IBaSr3 tetrahedra. In the second I site, I(2) is bonded in a 4-coordinate geometry to one Ba(1), one Sr(2), and two equivalent Sr(1) atoms. In the third I site, I(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ba(1) and one Sr(2) atom. In the fourth I site, I(4) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1) and two equivalent Sr(2) atoms. In the fifth I site, I(5) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Sr(1), and one Sr(2) atom. In the sixth I site, I(6) is bonded to one Ba(1), one Sr(2), and two equivalent Sr(1) atoms to form a mixture of distorted corner and edge-sharing IBaSr3 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_BaSr2I6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.280
_cell_length_b   8.503
_cell_length_c   24.789
_cell_angle_alpha   87.572
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1743.698
_cell_formula_units_Z   4
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
  Ba  Ba0  1  0.961  0.833  0.594  1.0
  Ba  Ba1  1  0.539  0.833  0.094  1.0
  Ba  Ba2  1  0.461  0.167  0.906  1.0
  Ba  Ba3  1  0.039  0.167  0.406  1.0
  Sr  Sr4  1  0.462  0.768  0.743  1.0
  Sr  Sr5  1  0.030  0.662  0.907  1.0
  Sr  Sr6  1  0.038  0.768  0.243  1.0
  Sr  Sr7  1  0.470  0.662  0.407  1.0
  Sr  Sr8  1  0.530  0.338  0.593  1.0
  Sr  Sr9  1  0.962  0.232  0.757  1.0
  Sr  Sr10  1  0.970  0.338  0.093  1.0
  Sr  Sr11  1  0.538  0.232  0.257  1.0
  I  I12  1  0.195  0.955  0.820  1.0
  I  I13  1  0.714  0.896  0.840  1.0
  I  I14  1  0.286  0.861  0.982  1.0
  I  I15  1  0.305  0.955  0.320  1.0
  I  I16  1  0.786  0.896  0.340  1.0
  I  I17  1  0.214  0.861  0.482  1.0
  I  I18  1  0.694  0.632  0.517  1.0
  I  I19  1  0.273  0.596  0.646  1.0
  I  I20  1  0.761  0.535  0.687  1.0
  I  I21  1  0.261  0.465  0.813  1.0
  I  I22  1  0.806  0.632  0.017  1.0
  I  I23  1  0.773  0.404  0.854  1.0
  I  I24  1  0.227  0.596  0.146  1.0
  I  I25  1  0.194  0.368  0.983  1.0
  I  I26  1  0.739  0.535  0.187  1.0
  I  I27  1  0.239  0.465  0.313  1.0
  I  I28  1  0.727  0.404  0.354  1.0
  I  I29  1  0.306  0.368  0.483  1.0
  I  I30  1  0.786  0.139  0.518  1.0
  I  I31  1  0.214  0.104  0.660  1.0
  I  I32  1  0.695  0.045  0.680  1.0
  I  I33  1  0.714  0.139  0.018  1.0
  I  I34  1  0.286  0.104  0.160  1.0
  I  I35  1  0.805  0.045  0.180  1.0
[/CIF]
.