The crystal structure described by Ba2Sr7I18 crystallizes in the triclinic P-1 space group. Ba(1) is bonded in a 7-coordinate geometry to one I(1), one I(2), one I(3), one I(6), one I(8), and two equivalent I(9) atoms. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one I(1), one I(2), one I(4), one I(6), one I(8), and one I(9) atom to form a mixture of corner and edge-sharing SrI6 octahedra. The corner-sharing octahedral tilt angles range from 51-65°. In the second Sr site, Sr(2) is bonded to two equivalent I(3), two equivalent I(4), and two equivalent I(9) atoms to form a mixture of corner and edge-sharing SrI6 octahedra. The corner-sharing octahedral tilt angles range from 62-66°. In the third Sr site, Sr(3) is bonded to one I(1), one I(2), one I(3), one I(5), one I(7), and one I(8) atom to form a mixture of corner and edge-sharing SrI6 octahedra. The corner-sharing octahedral tilt angles range from 51-64°. In the fourth Sr site, Sr(4) is bonded to one I(4), one I(6), one I(7), one I(8), and two equivalent I(5) atoms to form a mixture of corner and edge-sharing SrI6 octahedra. The corner-sharing octahedral tilt angles range from 53-66°. There are nine inequivalent I sites. In the first I site, I(1) is bonded in a 3-coordinate geometry to one Ba(1), one Sr(1), and one Sr(3) atom. In the second I site, I(2) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Sr(1), and one Sr(3) atom. In the third I site, I(3) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Sr(2), and one Sr(3) atom. In the fourth I site, I(4) is bonded in a trigonal non-coplanar geometry to one Sr(1), one Sr(2), and one Sr(4) atom. In the fifth I site, I(5) is bonded in a distorted T-shaped geometry to one Sr(3) and two equivalent Sr(4) atoms. In the sixth I site, I(6) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Sr(1), and one Sr(4) atom. In the seventh I site, I(7) is bonded in an L-shaped geometry to one Sr(3) and one Sr(4) atom. In the eighth I site, I(8) is bonded in a 4-coordinate geometry to one Ba(1), one Sr(1), one Sr(3), and one Sr(4) atom. In the ninth I site, I(9) is bonded to two equivalent Ba(1), one Sr(1), and one Sr(2) atom to form a mixture of distorted corner and edge-sharing IBa2Sr2 trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2Sr7I18
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.746
_cell_length_b   11.523
_cell_length_c   12.091
_cell_angle_alpha   79.227
_cell_angle_beta   63.643
_cell_angle_gamma   83.794
_symmetry_Int_Tables_number   1
_cell_volume   1317.392
_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
  Ba  Ba0  1  0.530  0.389  0.781  1.0
  Ba  Ba1  1  0.470  0.611  0.219  1.0
  Sr  Sr2  1  0.327  0.825  0.881  1.0
  Sr  Sr3  1  0.000  0.500  0.000  1.0
  Sr  Sr4  1  0.817  0.779  0.384  1.0
  Sr  Sr5  1  0.114  0.112  0.295  1.0
  Sr  Sr6  1  0.886  0.888  0.705  1.0
  Sr  Sr7  1  0.183  0.221  0.616  1.0
  Sr  Sr8  1  0.673  0.175  0.119  1.0
  I  I9  1  0.386  0.099  0.748  1.0
  I  I10  1  0.519  0.690  0.635  1.0
  I  I11  1  0.770  0.551  0.278  1.0
  I  I12  1  0.988  0.211  0.087  1.0
  I  I13  1  0.795  0.030  0.486  1.0
  I  I14  1  0.588  0.817  0.946  1.0
  I  I15  1  0.943  0.654  0.579  1.0
  I  I16  1  0.160  0.844  0.197  1.0
  I  I17  1  0.708  0.460  0.972  1.0
  I  I18  1  0.292  0.540  0.028  1.0
  I  I19  1  0.840  0.156  0.803  1.0
  I  I20  1  0.057  0.346  0.421  1.0
  I  I21  1  0.412  0.183  0.054  1.0
  I  I22  1  0.205  0.970  0.514  1.0
  I  I23  1  0.012  0.789  0.913  1.0
  I  I24  1  0.230  0.449  0.722  1.0
  I  I25  1  0.481  0.310  0.365  1.0
  I  I26  1  0.614  0.901  0.252  1.0
[/CIF]
.
The crystal structure described by Ba2Sr7I18 crystallizes in the triclinic P-1 space group. Ba(1) is bonded in a 7-coordinate geometry to one I(1), one I(2), one I(3), one I(6), one I(8), and two equivalent I(9) atoms. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one I(1), one I(2), one I(4), one I(6), one I(8), and one I(9) atom to form a mixture of corner and edge-sharing SrI6 octahedra. The corner-sharing octahedral tilt angles range from 51-65°. In the second Sr site, Sr(2) is bonded to two equivalent I(3), two equivalent I(4), and two equivalent I(9) atoms to form a mixture of corner and edge-sharing SrI6 octahedra. The corner-sharing octahedral tilt angles range from 62-66°. In the third Sr site, Sr(3) is bonded to one I(1), one I(2), one I(3), one I(5), one I(7), and one I(8) atom to form a mixture of corner and edge-sharing SrI6 octahedra. The corner-sharing octahedral tilt angles range from 51-64°. In the fourth Sr site, Sr(4) is bonded to one I(4), one I(6), one I(7), one I(8), and two equivalent I(5) atoms to form a mixture of corner and edge-sharing SrI6 octahedra. The corner-sharing octahedral tilt angles range from 53-66°. There are nine inequivalent I sites. In the first I site, I(1) is bonded in a 3-coordinate geometry to one Ba(1), one Sr(1), and one Sr(3) atom. In the second I site, I(2) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Sr(1), and one Sr(3) atom. In the third I site, I(3) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Sr(2), and one Sr(3) atom. In the fourth I site, I(4) is bonded in a trigonal non-coplanar geometry to one Sr(1), one Sr(2), and one Sr(4) atom. In the fifth I site, I(5) is bonded in a distorted T-shaped geometry to one Sr(3) and two equivalent Sr(4) atoms. In the sixth I site, I(6) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Sr(1), and one Sr(4) atom. In the seventh I site, I(7) is bonded in an L-shaped geometry to one Sr(3) and one Sr(4) atom. In the eighth I site, I(8) is bonded in a 4-coordinate geometry to one Ba(1), one Sr(1), one Sr(3), and one Sr(4) atom. In the ninth I site, I(9) is bonded to two equivalent Ba(1), one Sr(1), and one Sr(2) atom to form a mixture of distorted corner and edge-sharing IBa2Sr2 trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2Sr7I18
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.746
_cell_length_b   11.523
_cell_length_c   12.091
_cell_angle_alpha   79.227
_cell_angle_beta   63.643
_cell_angle_gamma   83.794
_symmetry_Int_Tables_number   1
_cell_volume   1317.392
_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
  Ba  Ba0  1  0.530  0.389  0.781  1.0
  Ba  Ba1  1  0.470  0.611  0.219  1.0
  Sr  Sr2  1  0.327  0.825  0.881  1.0
  Sr  Sr3  1  0.000  0.500  0.000  1.0
  Sr  Sr4  1  0.817  0.779  0.384  1.0
  Sr  Sr5  1  0.114  0.112  0.295  1.0
  Sr  Sr6  1  0.886  0.888  0.705  1.0
  Sr  Sr7  1  0.183  0.221  0.616  1.0
  Sr  Sr8  1  0.673  0.175  0.119  1.0
  I  I9  1  0.386  0.099  0.748  1.0
  I  I10  1  0.519  0.690  0.635  1.0
  I  I11  1  0.770  0.551  0.278  1.0
  I  I12  1  0.988  0.211  0.087  1.0
  I  I13  1  0.795  0.030  0.486  1.0
  I  I14  1  0.588  0.817  0.946  1.0
  I  I15  1  0.943  0.654  0.579  1.0
  I  I16  1  0.160  0.844  0.197  1.0
  I  I17  1  0.708  0.460  0.972  1.0
  I  I18  1  0.292  0.540  0.028  1.0
  I  I19  1  0.840  0.156  0.803  1.0
  I  I20  1  0.057  0.346  0.421  1.0
  I  I21  1  0.412  0.183  0.054  1.0
  I  I22  1  0.205  0.970  0.514  1.0
  I  I23  1  0.012  0.789  0.913  1.0
  I  I24  1  0.230  0.449  0.722  1.0
  I  I25  1  0.481  0.310  0.365  1.0
  I  I26  1  0.614  0.901  0.252  1.0
[/CIF]
.