The crystal structure described by Sr2CaI6 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one I(2), one I(4), one I(5), one I(6), and two equivalent I(3) atoms to form distorted SrI6 octahedra that share corners with five equivalent Ca(1)I6 octahedra and  an edgeedge with one Sr(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one I(1), one I(2), one I(3), one I(4), one I(5), and two equivalent I(6) atoms. Ca(1) is bonded to one I(2), one I(3), one I(4), one I(5), and two equivalent I(1) atoms to form CaI6 octahedra that share corners with five equivalent Sr(1)I6 octahedra and  an edgeedge with one Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. There are six inequivalent I sites. In the first I site, I(1) is bonded in a trigonal planar geometry to one Sr(2) and two equivalent Ca(1) atoms. In the second I site, I(2) is bonded in a trigonal non-coplanar geometry to one Sr(1), one Sr(2), and one Ca(1) atom. In the third I site, I(3) is bonded in a 4-coordinate geometry to one Sr(2), two equivalent Sr(1), and one Ca(1) atom. In the fourth I site, I(4) is bonded in a distorted trigonal planar geometry to one Sr(1), one Sr(2), and one Ca(1) atom. In the fifth I site, I(5) is bonded in a distorted trigonal planar geometry to one Sr(1), one Sr(2), and one Ca(1) atom. In the sixth I site, I(6) is bonded in a trigonal non-coplanar geometry to one Sr(1) and two equivalent Sr(2) atoms. is represented by the CIF file [CIF]
data_Sr2CaI6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   16.960
_cell_length_b   10.016
_cell_length_c   11.277
_cell_angle_alpha   57.292
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1611.788
_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
  Sr  Sr0  1  0.079  0.812  0.734  1.0
  Sr  Sr1  1  0.579  0.188  0.766  1.0
  Sr  Sr2  1  0.254  0.236  0.781  1.0
  Sr  Sr3  1  0.754  0.764  0.719  1.0
  Sr  Sr4  1  0.246  0.236  0.281  1.0
  Sr  Sr5  1  0.746  0.764  0.219  1.0
  Sr  Sr6  1  0.421  0.812  0.234  1.0
  Sr  Sr7  1  0.921  0.188  0.266  1.0
  Ca  Ca8  1  0.906  0.332  0.706  1.0
  Ca  Ca9  1  0.406  0.668  0.794  1.0
  Ca  Ca10  1  0.594  0.332  0.206  1.0
  Ca  Ca11  1  0.094  0.668  0.294  1.0
  I  I12  1  0.087  0.400  0.626  1.0
  I  I13  1  0.426  0.425  0.692  1.0
  I  I14  1  0.920  0.075  0.609  1.0
  I  I15  1  0.729  0.450  0.665  1.0
  I  I16  1  0.229  0.550  0.835  1.0
  I  I17  1  0.602  0.091  0.534  1.0
  I  I18  1  0.926  0.575  0.808  1.0
  I  I19  1  0.231  0.053  0.617  1.0
  I  I20  1  0.731  0.947  0.883  1.0
  I  I21  1  0.413  0.400  0.126  1.0
  I  I22  1  0.102  0.909  0.966  1.0
  I  I23  1  0.580  0.075  0.109  1.0
  I  I24  1  0.420  0.925  0.891  1.0
  I  I25  1  0.898  0.091  0.034  1.0
  I  I26  1  0.587  0.600  0.874  1.0
  I  I27  1  0.269  0.053  0.117  1.0
  I  I28  1  0.769  0.947  0.383  1.0
  I  I29  1  0.074  0.425  0.192  1.0
  I  I30  1  0.398  0.909  0.466  1.0
  I  I31  1  0.771  0.450  0.165  1.0
  I  I32  1  0.271  0.550  0.335  1.0
  I  I33  1  0.080  0.925  0.391  1.0
  I  I34  1  0.574  0.575  0.308  1.0
  I  I35  1  0.913  0.600  0.374  1.0
[/CIF]
.
The crystal structure described by Sr2CaI6 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one I(2), one I(4), one I(5), one I(6), and two equivalent I(3) atoms to form distorted SrI6 octahedra that share corners with five equivalent Ca(1)I6 octahedra and  an edgeedge with one Sr(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one I(1), one I(2), one I(3), one I(4), one I(5), and two equivalent I(6) atoms. Ca(1) is bonded to one I(2), one I(3), one I(4), one I(5), and two equivalent I(1) atoms to form CaI6 octahedra that share corners with five equivalent Sr(1)I6 octahedra and  an edgeedge with one Ca(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. There are six inequivalent I sites. In the first I site, I(1) is bonded in a trigonal planar geometry to one Sr(2) and two equivalent Ca(1) atoms. In the second I site, I(2) is bonded in a trigonal non-coplanar geometry to one Sr(1), one Sr(2), and one Ca(1) atom. In the third I site, I(3) is bonded in a 4-coordinate geometry to one Sr(2), two equivalent Sr(1), and one Ca(1) atom. In the fourth I site, I(4) is bonded in a distorted trigonal planar geometry to one Sr(1), one Sr(2), and one Ca(1) atom. In the fifth I site, I(5) is bonded in a distorted trigonal planar geometry to one Sr(1), one Sr(2), and one Ca(1) atom. In the sixth I site, I(6) is bonded in a trigonal non-coplanar geometry to one Sr(1) and two equivalent Sr(2) atoms. is represented by the CIF file [CIF]
data_Sr2CaI6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   16.960
_cell_length_b   10.016
_cell_length_c   11.277
_cell_angle_alpha   57.292
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1611.788
_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
  Sr  Sr0  1  0.079  0.812  0.734  1.0
  Sr  Sr1  1  0.579  0.188  0.766  1.0
  Sr  Sr2  1  0.254  0.236  0.781  1.0
  Sr  Sr3  1  0.754  0.764  0.719  1.0
  Sr  Sr4  1  0.246  0.236  0.281  1.0
  Sr  Sr5  1  0.746  0.764  0.219  1.0
  Sr  Sr6  1  0.421  0.812  0.234  1.0
  Sr  Sr7  1  0.921  0.188  0.266  1.0
  Ca  Ca8  1  0.906  0.332  0.706  1.0
  Ca  Ca9  1  0.406  0.668  0.794  1.0
  Ca  Ca10  1  0.594  0.332  0.206  1.0
  Ca  Ca11  1  0.094  0.668  0.294  1.0
  I  I12  1  0.087  0.400  0.626  1.0
  I  I13  1  0.426  0.425  0.692  1.0
  I  I14  1  0.920  0.075  0.609  1.0
  I  I15  1  0.729  0.450  0.665  1.0
  I  I16  1  0.229  0.550  0.835  1.0
  I  I17  1  0.602  0.091  0.534  1.0
  I  I18  1  0.926  0.575  0.808  1.0
  I  I19  1  0.231  0.053  0.617  1.0
  I  I20  1  0.731  0.947  0.883  1.0
  I  I21  1  0.413  0.400  0.126  1.0
  I  I22  1  0.102  0.909  0.966  1.0
  I  I23  1  0.580  0.075  0.109  1.0
  I  I24  1  0.420  0.925  0.891  1.0
  I  I25  1  0.898  0.091  0.034  1.0
  I  I26  1  0.587  0.600  0.874  1.0
  I  I27  1  0.269  0.053  0.117  1.0
  I  I28  1  0.769  0.947  0.383  1.0
  I  I29  1  0.074  0.425  0.192  1.0
  I  I30  1  0.398  0.909  0.466  1.0
  I  I31  1  0.771  0.450  0.165  1.0
  I  I32  1  0.271  0.550  0.335  1.0
  I  I33  1  0.080  0.925  0.391  1.0
  I  I34  1  0.574  0.575  0.308  1.0
  I  I35  1  0.913  0.600  0.374  1.0
[/CIF]
.