The material structure described by Ba3LaI9 crystallizes in the monoclinic Pc space group. There are six inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to one I(1), one I(10), one I(13), one I(14), one I(4), one I(5), and one I(9) atom to form distorted BaI7 pentagonal bipyramids that share corners with two equivalent Ba(6)I7 pentagonal bipyramids, corners with two equivalent La(2)I7 pentagonal bipyramids,  an edgeedge with one Ba(3)I7 pentagonal bipyramid, and edges with two equivalent Ba(6)I7 pentagonal bipyramids. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one I(11), one I(12), one I(15), one I(2), one I(3), one I(6), one I(7), and one I(8) atom. In the third Ba site, Ba(3) is bonded to one I(12), one I(13), one I(17), one I(18), one I(3), one I(8), and one I(9) atom to form distorted BaI7 pentagonal bipyramids that share corners with two equivalent Ba(6)I7 pentagonal bipyramids, corners with two equivalent La(2)I7 pentagonal bipyramids,  an edgeedge with one Ba(1)I7 pentagonal bipyramid, and edges with two equivalent La(2)I7 pentagonal bipyramids. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to one I(1), one I(10), one I(11), one I(14), one I(15), one I(16), one I(2), and one I(7) atom. In the fifth Ba site, Ba(5) is bonded in a 8-coordinate geometry to one I(11), one I(12), one I(15), one I(16), one I(17), one I(2), one I(3), and one I(6) atom. In the sixth Ba site, Ba(6) is bonded to one I(1), one I(10), one I(13), one I(14), one I(18), one I(4), and one I(5) atom to form distorted BaI7 pentagonal bipyramids that share corners with two equivalent Ba(1)I7 pentagonal bipyramids, corners with two equivalent Ba(3)I7 pentagonal bipyramids,  an edgeedge with one La(2)I7 pentagonal bipyramid, and edges with two equivalent Ba(1)I7 pentagonal bipyramids. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to one I(1), one I(10), one I(11), one I(16), one I(2), one I(5), one I(6), and one I(7) atom. In the second La site, La(2) is bonded to one I(12), one I(17), one I(18), one I(3), one I(4), one I(8), and one I(9) atom to form distorted LaI7 pentagonal bipyramids that share corners with two equivalent Ba(1)I7 pentagonal bipyramids, corners with two equivalent Ba(3)I7 pentagonal bipyramids,  an edgeedge with one Ba(6)I7 pentagonal bipyramid, and edges with two equivalent Ba(3)I7 pentagonal bipyramids. There are eighteen inequivalent I sites. In the first I site, I(1) is bonded to one Ba(1), one Ba(4), one Ba(6), and one La(1) atom to form a mixture of corner and edge-sharing IBa3La tetrahedra. In the second I site, I(2) is bonded to one Ba(2), one Ba(4), one Ba(5), and one La(1) atom to form a mixture of corner and edge-sharing IBa3La tetrahedra. In the third I site, I(3) is bonded to one Ba(2), one Ba(3), one Ba(5), and one La(2) atom to form a mixture of corner and edge-sharing IBa3La tetrahedra. In the fourth I site, I(4) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Ba(6), and one La(2) atom. In the fifth I site, I(5) is bonded in a trigonal planar geometry to one Ba(1), one Ba(6), and one La(1) atom. In the sixth I site, I(6) is bonded in a trigonal non-coplanar geometry to one Ba(2), one Ba(5), and one La(1) atom. In the seventh I site, I(7) is bonded in a distorted trigonal non-coplanar geometry to one Ba(2), one Ba(4), and one La(1) atom. In the eighth I site, I(8) is bonded in a distorted trigonal planar geometry to one Ba(2), one Ba(3), and one La(2) atom. In the ninth I site, I(9) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Ba(3), and one La(2) atom. In the tenth I site, I(10) is bonded to one Ba(1), one Ba(4), one Ba(6), and one La(1) atom to form a mixture of distorted corner and edge-sharing IBa3La tetrahedra. In the eleventh I site, I(11) is bonded to one Ba(2), one Ba(4), one Ba(5), and one La(1) atom to form a mixture of distorted corner and edge-sharing IBa3La tetrahedra. In the twelfth I site, I(12) is bonded to one Ba(2), one Ba(3), one Ba(5), and one La(2) atom to form a mixture of corner and edge-sharing IBa3La tetrahedra. In the thirteenth I site, I(13) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Ba(3), and one Ba(6) atom. In the fourteenth I site, I(14) is bonded in a trigonal planar geometry to one Ba(1), one Ba(4), and one Ba(6) atom. In the fifteenth I site, I(15) is bonded in a distorted trigonal non-coplanar geometry to one Ba(2), one Ba(4), and one Ba(5) atom. In the sixteenth I site, I(16) is bonded in a distorted trigonal non-coplanar geometry to one Ba(4), one Ba(5), and one La(1) atom. In the seventeenth I site, I(17) is bonded in a trigonal planar geometry to one Ba(3), one Ba(5), and one La(2) atom. In the eighteenth I site, I(18) is bonded in a trigonal non-coplanar geometry to one Ba(3), one Ba(6), and one La(2) atom. is represented by the CIF file [CIF]
data_Ba3LaI9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.089
_cell_length_b   8.691
_cell_length_c   33.899
_cell_angle_alpha   87.916
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   2381.801
_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  0.970  0.679  0.933  1.0
  Ba  Ba1  1  0.003  0.706  0.692  1.0
  Ba  Ba2  1  0.030  0.679  0.433  1.0
  Ba  Ba3  1  0.997  0.706  0.192  1.0
  Ba  Ba4  1  0.986  0.317  0.570  1.0
  Ba  Ba5  1  0.982  0.284  0.808  1.0
  Ba  Ba6  1  0.014  0.317  0.070  1.0
  Ba  Ba7  1  0.018  0.284  0.308  1.0
  Ba  Ba8  1  0.527  0.215  0.692  1.0
  Ba  Ba9  1  0.517  0.178  0.931  1.0
  Ba  Ba10  1  0.473  0.215  0.192  1.0
  Ba  Ba11  1  0.483  0.178  0.431  1.0
  La  La12  1  0.520  0.798  0.807  1.0
  La  La13  1  0.546  0.821  0.567  1.0
  La  La14  1  0.480  0.798  0.307  1.0
  La  La15  1  0.454  0.821  0.067  1.0
  I  I16  1  0.797  0.978  0.868  1.0
  I  I17  1  0.816  0.984  0.753  1.0
  I  I18  1  0.812  0.993  0.627  1.0
  I  I19  1  0.203  0.978  0.368  1.0
  I  I20  1  0.184  0.984  0.253  1.0
  I  I21  1  0.702  0.891  0.994  1.0
  I  I22  1  0.188  0.993  0.127  1.0
  I  I23  1  0.333  0.846  0.892  1.0
  I  I24  1  0.298  0.891  0.494  1.0
  I  I25  1  0.399  0.841  0.708  1.0
  I  I26  1  0.667  0.846  0.392  1.0
  I  I27  1  0.601  0.841  0.208  1.0
  I  I28  1  0.162  0.646  0.796  1.0
  I  I29  1  0.211  0.651  0.599  1.0
  I  I30  1  0.838  0.646  0.296  1.0
  I  I31  1  0.789  0.651  0.099  1.0
  I  I32  1  0.743  0.588  0.511  1.0
  I  I33  1  0.677  0.508  0.867  1.0
  I  I34  1  0.691  0.514  0.752  1.0
  I  I35  1  0.697  0.527  0.628  1.0
  I  I36  1  0.257  0.588  0.011  1.0
  I  I37  1  0.323  0.508  0.367  1.0
  I  I38  1  0.309  0.514  0.252  1.0
  I  I39  1  0.303  0.527  0.128  1.0
  I  I40  1  0.762  0.398  0.990  1.0
  I  I41  1  0.238  0.398  0.490  1.0
  I  I42  1  0.151  0.344  0.901  1.0
  I  I43  1  0.111  0.322  0.699  1.0
  I  I44  1  0.849  0.344  0.401  1.0
  I  I45  1  0.889  0.322  0.199  1.0
  I  I46  1  0.393  0.148  0.798  1.0
  I  I47  1  0.356  0.124  0.599  1.0
  I  I48  1  0.607  0.148  0.298  1.0
  I  I49  1  0.644  0.124  0.099  1.0
  I  I50  1  0.755  0.066  0.510  1.0
  I  I51  1  0.245  0.066  0.010  1.0
[/CIF]
.
The material structure described by Ba3LaI9 crystallizes in the monoclinic Pc space group. There are six inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to one I(1), one I(10), one I(13), one I(14), one I(4), one I(5), and one I(9) atom to form distorted BaI7 pentagonal bipyramids that share corners with two equivalent Ba(6)I7 pentagonal bipyramids, corners with two equivalent La(2)I7 pentagonal bipyramids,  an edgeedge with one Ba(3)I7 pentagonal bipyramid, and edges with two equivalent Ba(6)I7 pentagonal bipyramids. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one I(11), one I(12), one I(15), one I(2), one I(3), one I(6), one I(7), and one I(8) atom. In the third Ba site, Ba(3) is bonded to one I(12), one I(13), one I(17), one I(18), one I(3), one I(8), and one I(9) atom to form distorted BaI7 pentagonal bipyramids that share corners with two equivalent Ba(6)I7 pentagonal bipyramids, corners with two equivalent La(2)I7 pentagonal bipyramids,  an edgeedge with one Ba(1)I7 pentagonal bipyramid, and edges with two equivalent La(2)I7 pentagonal bipyramids. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to one I(1), one I(10), one I(11), one I(14), one I(15), one I(16), one I(2), and one I(7) atom. In the fifth Ba site, Ba(5) is bonded in a 8-coordinate geometry to one I(11), one I(12), one I(15), one I(16), one I(17), one I(2), one I(3), and one I(6) atom. In the sixth Ba site, Ba(6) is bonded to one I(1), one I(10), one I(13), one I(14), one I(18), one I(4), and one I(5) atom to form distorted BaI7 pentagonal bipyramids that share corners with two equivalent Ba(1)I7 pentagonal bipyramids, corners with two equivalent Ba(3)I7 pentagonal bipyramids,  an edgeedge with one La(2)I7 pentagonal bipyramid, and edges with two equivalent Ba(1)I7 pentagonal bipyramids. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to one I(1), one I(10), one I(11), one I(16), one I(2), one I(5), one I(6), and one I(7) atom. In the second La site, La(2) is bonded to one I(12), one I(17), one I(18), one I(3), one I(4), one I(8), and one I(9) atom to form distorted LaI7 pentagonal bipyramids that share corners with two equivalent Ba(1)I7 pentagonal bipyramids, corners with two equivalent Ba(3)I7 pentagonal bipyramids,  an edgeedge with one Ba(6)I7 pentagonal bipyramid, and edges with two equivalent Ba(3)I7 pentagonal bipyramids. There are eighteen inequivalent I sites. In the first I site, I(1) is bonded to one Ba(1), one Ba(4), one Ba(6), and one La(1) atom to form a mixture of corner and edge-sharing IBa3La tetrahedra. In the second I site, I(2) is bonded to one Ba(2), one Ba(4), one Ba(5), and one La(1) atom to form a mixture of corner and edge-sharing IBa3La tetrahedra. In the third I site, I(3) is bonded to one Ba(2), one Ba(3), one Ba(5), and one La(2) atom to form a mixture of corner and edge-sharing IBa3La tetrahedra. In the fourth I site, I(4) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Ba(6), and one La(2) atom. In the fifth I site, I(5) is bonded in a trigonal planar geometry to one Ba(1), one Ba(6), and one La(1) atom. In the sixth I site, I(6) is bonded in a trigonal non-coplanar geometry to one Ba(2), one Ba(5), and one La(1) atom. In the seventh I site, I(7) is bonded in a distorted trigonal non-coplanar geometry to one Ba(2), one Ba(4), and one La(1) atom. In the eighth I site, I(8) is bonded in a distorted trigonal planar geometry to one Ba(2), one Ba(3), and one La(2) atom. In the ninth I site, I(9) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Ba(3), and one La(2) atom. In the tenth I site, I(10) is bonded to one Ba(1), one Ba(4), one Ba(6), and one La(1) atom to form a mixture of distorted corner and edge-sharing IBa3La tetrahedra. In the eleventh I site, I(11) is bonded to one Ba(2), one Ba(4), one Ba(5), and one La(1) atom to form a mixture of distorted corner and edge-sharing IBa3La tetrahedra. In the twelfth I site, I(12) is bonded to one Ba(2), one Ba(3), one Ba(5), and one La(2) atom to form a mixture of corner and edge-sharing IBa3La tetrahedra. In the thirteenth I site, I(13) is bonded in a trigonal non-coplanar geometry to one Ba(1), one Ba(3), and one Ba(6) atom. In the fourteenth I site, I(14) is bonded in a trigonal planar geometry to one Ba(1), one Ba(4), and one Ba(6) atom. In the fifteenth I site, I(15) is bonded in a distorted trigonal non-coplanar geometry to one Ba(2), one Ba(4), and one Ba(5) atom. In the sixteenth I site, I(16) is bonded in a distorted trigonal non-coplanar geometry to one Ba(4), one Ba(5), and one La(1) atom. In the seventeenth I site, I(17) is bonded in a trigonal planar geometry to one Ba(3), one Ba(5), and one La(2) atom. In the eighteenth I site, I(18) is bonded in a trigonal non-coplanar geometry to one Ba(3), one Ba(6), and one La(2) atom. is represented by the CIF file [CIF]
data_Ba3LaI9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.089
_cell_length_b   8.691
_cell_length_c   33.899
_cell_angle_alpha   87.916
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   2381.801
_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  0.970  0.679  0.933  1.0
  Ba  Ba1  1  0.003  0.706  0.692  1.0
  Ba  Ba2  1  0.030  0.679  0.433  1.0
  Ba  Ba3  1  0.997  0.706  0.192  1.0
  Ba  Ba4  1  0.986  0.317  0.570  1.0
  Ba  Ba5  1  0.982  0.284  0.808  1.0
  Ba  Ba6  1  0.014  0.317  0.070  1.0
  Ba  Ba7  1  0.018  0.284  0.308  1.0
  Ba  Ba8  1  0.527  0.215  0.692  1.0
  Ba  Ba9  1  0.517  0.178  0.931  1.0
  Ba  Ba10  1  0.473  0.215  0.192  1.0
  Ba  Ba11  1  0.483  0.178  0.431  1.0
  La  La12  1  0.520  0.798  0.807  1.0
  La  La13  1  0.546  0.821  0.567  1.0
  La  La14  1  0.480  0.798  0.307  1.0
  La  La15  1  0.454  0.821  0.067  1.0
  I  I16  1  0.797  0.978  0.868  1.0
  I  I17  1  0.816  0.984  0.753  1.0
  I  I18  1  0.812  0.993  0.627  1.0
  I  I19  1  0.203  0.978  0.368  1.0
  I  I20  1  0.184  0.984  0.253  1.0
  I  I21  1  0.702  0.891  0.994  1.0
  I  I22  1  0.188  0.993  0.127  1.0
  I  I23  1  0.333  0.846  0.892  1.0
  I  I24  1  0.298  0.891  0.494  1.0
  I  I25  1  0.399  0.841  0.708  1.0
  I  I26  1  0.667  0.846  0.392  1.0
  I  I27  1  0.601  0.841  0.208  1.0
  I  I28  1  0.162  0.646  0.796  1.0
  I  I29  1  0.211  0.651  0.599  1.0
  I  I30  1  0.838  0.646  0.296  1.0
  I  I31  1  0.789  0.651  0.099  1.0
  I  I32  1  0.743  0.588  0.511  1.0
  I  I33  1  0.677  0.508  0.867  1.0
  I  I34  1  0.691  0.514  0.752  1.0
  I  I35  1  0.697  0.527  0.628  1.0
  I  I36  1  0.257  0.588  0.011  1.0
  I  I37  1  0.323  0.508  0.367  1.0
  I  I38  1  0.309  0.514  0.252  1.0
  I  I39  1  0.303  0.527  0.128  1.0
  I  I40  1  0.762  0.398  0.990  1.0
  I  I41  1  0.238  0.398  0.490  1.0
  I  I42  1  0.151  0.344  0.901  1.0
  I  I43  1  0.111  0.322  0.699  1.0
  I  I44  1  0.849  0.344  0.401  1.0
  I  I45  1  0.889  0.322  0.199  1.0
  I  I46  1  0.393  0.148  0.798  1.0
  I  I47  1  0.356  0.124  0.599  1.0
  I  I48  1  0.607  0.148  0.298  1.0
  I  I49  1  0.644  0.124  0.099  1.0
  I  I50  1  0.755  0.066  0.510  1.0
  I  I51  1  0.245  0.066  0.010  1.0
[/CIF]
.