The material described by Ba3YI9 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 Y(2)I7 pentagonal bipyramids and  an edgeedge with one Ba(3)I7 pentagonal bipyramid. 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 Y(2)I7 pentagonal bipyramids,  an edgeedge with one Ba(1)I7 pentagonal bipyramid, and edges with two equivalent Y(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 in a 7-coordinate geometry to one I(1), one I(10), one I(13), one I(14), one I(18), one I(4), and one I(5) atom. There are two inequivalent Y sites. In the first Y site, Y(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 Y site, Y(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 YI7 pentagonal bipyramids that share corners with two equivalent Ba(1)I7 pentagonal bipyramids, corners with two equivalent Ba(3)I7 pentagonal bipyramids, 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 Y(1) atom to form edge-sharing IBa3Y tetrahedra. In the second I site, I(2) is bonded to one Ba(2), one Ba(4), one Ba(5), and one Y(1) atom to form a mixture of edge and corner-sharing IBa3Y tetrahedra. In the third I site, I(3) is bonded to one Ba(2), one Ba(3), one Ba(5), and one Y(2) atom to form edge-sharing IBa3Y tetrahedra. In the fourth I site, I(4) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Ba(6), and one Y(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 Y(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 Y(1) atom. In the seventh I site, I(7) is bonded in a 3-coordinate geometry to one Ba(2), one Ba(4), and one Y(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 Y(2) atom. In the ninth I site, I(9) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Ba(3), and one Y(2) atom. In the tenth I site, I(10) is bonded to one Ba(1), one Ba(4), one Ba(6), and one Y(1) atom to form a mixture of distorted edge and corner-sharing IBa3Y tetrahedra. In the eleventh I site, I(11) is bonded in a distorted rectangular see-saw-like geometry to one Ba(2), one Ba(4), one Ba(5), and one Y(1) atom. In the twelfth I site, I(12) is bonded to one Ba(2), one Ba(3), one Ba(5), and one Y(2) atom to form a mixture of distorted edge and corner-sharing IBa3Y 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 Y(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 Y(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 Y(2) atom. is represented by the CIF file [CIF]
data_Ba3YI9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.986
_cell_length_b   8.596
_cell_length_c   33.673
_cell_angle_alpha   88.080
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   2310.421
_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  0.681  0.933  1.0
  Ba  Ba1  1  0.002  0.707  0.692  1.0
  Ba  Ba2  1  0.030  0.681  0.433  1.0
  Ba  Ba3  1  0.998  0.707  0.192  1.0
  Ba  Ba4  1  0.986  0.317  0.571  1.0
  Ba  Ba5  1  0.982  0.285  0.808  1.0
  Ba  Ba6  1  0.014  0.317  0.071  1.0
  Ba  Ba7  1  0.018  0.285  0.308  1.0
  Ba  Ba8  1  0.529  0.216  0.692  1.0
  Ba  Ba9  1  0.519  0.178  0.930  1.0
  Ba  Ba10  1  0.471  0.216  0.192  1.0
  Ba  Ba11  1  0.481  0.178  0.430  1.0
  Y  Y12  1  0.517  0.800  0.806  1.0
  Y  Y13  1  0.545  0.826  0.566  1.0
  Y  Y14  1  0.483  0.800  0.306  1.0
  Y  Y15  1  0.455  0.826  0.066  1.0
  I  I16  1  0.795  0.975  0.867  1.0
  I  I17  1  0.812  0.979  0.754  1.0
  I  I18  1  0.807  0.987  0.626  1.0
  I  I19  1  0.205  0.975  0.367  1.0
  I  I20  1  0.188  0.979  0.254  1.0
  I  I21  1  0.698  0.888  0.995  1.0
  I  I22  1  0.193  0.987  0.126  1.0
  I  I23  1  0.337  0.845  0.891  1.0
  I  I24  1  0.302  0.888  0.495  1.0
  I  I25  1  0.401  0.840  0.709  1.0
  I  I26  1  0.663  0.845  0.391  1.0
  I  I27  1  0.599  0.840  0.209  1.0
  I  I28  1  0.173  0.649  0.797  1.0
  I  I29  1  0.223  0.655  0.598  1.0
  I  I30  1  0.827  0.649  0.297  1.0
  I  I31  1  0.777  0.655  0.098  1.0
  I  I32  1  0.735  0.595  0.513  1.0
  I  I33  1  0.674  0.515  0.866  1.0
  I  I34  1  0.688  0.521  0.753  1.0
  I  I35  1  0.695  0.532  0.627  1.0
  I  I36  1  0.265  0.595  0.013  1.0
  I  I37  1  0.326  0.515  0.366  1.0
  I  I38  1  0.312  0.521  0.253  1.0
  I  I39  1  0.305  0.532  0.127  1.0
  I  I40  1  0.763  0.398  0.990  1.0
  I  I41  1  0.237  0.398  0.490  1.0
  I  I42  1  0.149  0.342  0.901  1.0
  I  I43  1  0.107  0.319  0.698  1.0
  I  I44  1  0.851  0.342  0.401  1.0
  I  I45  1  0.893  0.319  0.198  1.0
  I  I46  1  0.395  0.140  0.798  1.0
  I  I47  1  0.359  0.118  0.598  1.0
  I  I48  1  0.605  0.140  0.298  1.0
  I  I49  1  0.641  0.118  0.098  1.0
  I  I50  1  0.752  0.062  0.511  1.0
  I  I51  1  0.248  0.062  0.011  1.0
[/CIF]
.
The material described by Ba3YI9 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 Y(2)I7 pentagonal bipyramids and  an edgeedge with one Ba(3)I7 pentagonal bipyramid. 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 Y(2)I7 pentagonal bipyramids,  an edgeedge with one Ba(1)I7 pentagonal bipyramid, and edges with two equivalent Y(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 in a 7-coordinate geometry to one I(1), one I(10), one I(13), one I(14), one I(18), one I(4), and one I(5) atom. There are two inequivalent Y sites. In the first Y site, Y(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 Y site, Y(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 YI7 pentagonal bipyramids that share corners with two equivalent Ba(1)I7 pentagonal bipyramids, corners with two equivalent Ba(3)I7 pentagonal bipyramids, 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 Y(1) atom to form edge-sharing IBa3Y tetrahedra. In the second I site, I(2) is bonded to one Ba(2), one Ba(4), one Ba(5), and one Y(1) atom to form a mixture of edge and corner-sharing IBa3Y tetrahedra. In the third I site, I(3) is bonded to one Ba(2), one Ba(3), one Ba(5), and one Y(2) atom to form edge-sharing IBa3Y tetrahedra. In the fourth I site, I(4) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Ba(6), and one Y(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 Y(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 Y(1) atom. In the seventh I site, I(7) is bonded in a 3-coordinate geometry to one Ba(2), one Ba(4), and one Y(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 Y(2) atom. In the ninth I site, I(9) is bonded in a distorted trigonal non-coplanar geometry to one Ba(1), one Ba(3), and one Y(2) atom. In the tenth I site, I(10) is bonded to one Ba(1), one Ba(4), one Ba(6), and one Y(1) atom to form a mixture of distorted edge and corner-sharing IBa3Y tetrahedra. In the eleventh I site, I(11) is bonded in a distorted rectangular see-saw-like geometry to one Ba(2), one Ba(4), one Ba(5), and one Y(1) atom. In the twelfth I site, I(12) is bonded to one Ba(2), one Ba(3), one Ba(5), and one Y(2) atom to form a mixture of distorted edge and corner-sharing IBa3Y 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 Y(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 Y(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 Y(2) atom. is represented by the CIF file [CIF]
data_Ba3YI9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.986
_cell_length_b   8.596
_cell_length_c   33.673
_cell_angle_alpha   88.080
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   2310.421
_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  0.681  0.933  1.0
  Ba  Ba1  1  0.002  0.707  0.692  1.0
  Ba  Ba2  1  0.030  0.681  0.433  1.0
  Ba  Ba3  1  0.998  0.707  0.192  1.0
  Ba  Ba4  1  0.986  0.317  0.571  1.0
  Ba  Ba5  1  0.982  0.285  0.808  1.0
  Ba  Ba6  1  0.014  0.317  0.071  1.0
  Ba  Ba7  1  0.018  0.285  0.308  1.0
  Ba  Ba8  1  0.529  0.216  0.692  1.0
  Ba  Ba9  1  0.519  0.178  0.930  1.0
  Ba  Ba10  1  0.471  0.216  0.192  1.0
  Ba  Ba11  1  0.481  0.178  0.430  1.0
  Y  Y12  1  0.517  0.800  0.806  1.0
  Y  Y13  1  0.545  0.826  0.566  1.0
  Y  Y14  1  0.483  0.800  0.306  1.0
  Y  Y15  1  0.455  0.826  0.066  1.0
  I  I16  1  0.795  0.975  0.867  1.0
  I  I17  1  0.812  0.979  0.754  1.0
  I  I18  1  0.807  0.987  0.626  1.0
  I  I19  1  0.205  0.975  0.367  1.0
  I  I20  1  0.188  0.979  0.254  1.0
  I  I21  1  0.698  0.888  0.995  1.0
  I  I22  1  0.193  0.987  0.126  1.0
  I  I23  1  0.337  0.845  0.891  1.0
  I  I24  1  0.302  0.888  0.495  1.0
  I  I25  1  0.401  0.840  0.709  1.0
  I  I26  1  0.663  0.845  0.391  1.0
  I  I27  1  0.599  0.840  0.209  1.0
  I  I28  1  0.173  0.649  0.797  1.0
  I  I29  1  0.223  0.655  0.598  1.0
  I  I30  1  0.827  0.649  0.297  1.0
  I  I31  1  0.777  0.655  0.098  1.0
  I  I32  1  0.735  0.595  0.513  1.0
  I  I33  1  0.674  0.515  0.866  1.0
  I  I34  1  0.688  0.521  0.753  1.0
  I  I35  1  0.695  0.532  0.627  1.0
  I  I36  1  0.265  0.595  0.013  1.0
  I  I37  1  0.326  0.515  0.366  1.0
  I  I38  1  0.312  0.521  0.253  1.0
  I  I39  1  0.305  0.532  0.127  1.0
  I  I40  1  0.763  0.398  0.990  1.0
  I  I41  1  0.237  0.398  0.490  1.0
  I  I42  1  0.149  0.342  0.901  1.0
  I  I43  1  0.107  0.319  0.698  1.0
  I  I44  1  0.851  0.342  0.401  1.0
  I  I45  1  0.893  0.319  0.198  1.0
  I  I46  1  0.395  0.140  0.798  1.0
  I  I47  1  0.359  0.118  0.598  1.0
  I  I48  1  0.605  0.140  0.298  1.0
  I  I49  1  0.641  0.118  0.098  1.0
  I  I50  1  0.752  0.062  0.511  1.0
  I  I51  1  0.248  0.062  0.011  1.0
[/CIF]
.