The crystal structure described by Na2UI6 crystallizes in the triclinic P1 space group. There are six inequivalent Na sites. In the first Na site, Na(1) is bonded to one I(1), one I(2), one I(3), one I(4), one I(5), and one I(7) atom to form NaI6 octahedra that share  a cornercorner with one Na(2)I6 octahedra,  a cornercorner with one Na(6)I6 octahedra, corners with two equivalent Na(3)I6 octahedra, corners with three equivalent U(1)I6 octahedra, corners with three equivalent U(2)I6 octahedra, and  a faceface with one Na(3)I6 octahedra. The corner-sharing octahedral tilt angles range from 41-59°. In the second Na site, Na(2) is bonded to one I(10), one I(13), one I(5), one I(6), one I(8), and one I(9) atom to form NaI6 octahedra that share  a cornercorner with one Na(1)I6 octahedra,  an edgeedge with one Na(3)I6 octahedra,  an edgeedge with one U(3)I6 octahedra, edges with two equivalent Na(5)I6 octahedra, and edges with two equivalent U(2)I6 octahedra. The corner-sharing octahedral tilt angles are 56°. In the third Na site, Na(3) is bonded to one I(1), one I(3), one I(4), one I(5), one I(7), and one I(8) atom to form NaI6 octahedra that share corners with two equivalent Na(1)I6 octahedra,  an edgeedge with one Na(2)I6 octahedra,  an edgeedge with one U(1)I6 octahedra, edges with two equivalent U(2)I6 octahedra, and  a faceface with one Na(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 56-58°. In the fourth Na site, Na(4) is bonded to one I(11), one I(12), one I(14), one I(15), one I(16), and one I(18) atom to form NaI6 octahedra that share  an edgeedge with one Na(5)I6 octahedra,  an edgeedge with one U(1)I6 octahedra, edges with two equivalent Na(6)I6 octahedra, and edges with two equivalent U(3)I6 octahedra. In the fifth Na site, Na(5) is bonded to one I(10), one I(11), one I(13), one I(14), one I(6), and one I(9) atom to form NaI6 octahedra that share  an edgeedge with one Na(4)I6 octahedra,  an edgeedge with one U(2)I6 octahedra, edges with two equivalent Na(2)I6 octahedra, and edges with two equivalent U(3)I6 octahedra. In the sixth Na site, Na(6) is bonded to one I(12), one I(15), one I(16), one I(17), one I(18), and one I(2) atom to form NaI6 octahedra that share  a cornercorner with one Na(1)I6 octahedra,  an edgeedge with one U(3)I6 octahedra, edges with two equivalent Na(4)I6 octahedra, and edges with two equivalent U(1)I6 octahedra. The corner-sharing octahedral tilt angles are 59°. There are three inequivalent U sites. In the first U site, U(1) is bonded to one I(12), one I(16), one I(17), one I(2), one I(3), and one I(7) atom to form UI6 octahedra that share corners with three equivalent Na(1)I6 octahedra,  an edgeedge with one Na(3)I6 octahedra,  an edgeedge with one Na(4)I6 octahedra, and edges with two equivalent Na(6)I6 octahedra. The corner-sharing octahedral tilt angles range from 41-43°. In the second U site, U(2) is bonded to one I(1), one I(13), one I(4), one I(5), one I(8), and one I(9) atom to form UI6 octahedra that share corners with three equivalent Na(1)I6 octahedra,  an edgeedge with one Na(5)I6 octahedra, edges with two equivalent Na(2)I6 octahedra, and edges with two equivalent Na(3)I6 octahedra. The corner-sharing octahedral tilt angles range from 41-42°. In the third U site, U(3) is bonded to one I(10), one I(11), one I(14), one I(15), one I(18), and one I(6) atom to form UI6 octahedra that share  an edgeedge with one Na(2)I6 octahedra,  an edgeedge with one Na(6)I6 octahedra, edges with two equivalent Na(4)I6 octahedra, and edges with two equivalent Na(5)I6 octahedra. There are eighteen inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(3), and one U(2) atom. In the second I site, I(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(6), and one U(1) atom. In the third I site, I(3) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(3), and one U(1) atom. In the fourth I site, I(4) is bonded in a T-shaped geometry to one Na(1), one Na(3), and one U(2) atom. In the fifth I site, I(5) is bonded in a rectangular see-saw-like geometry to one Na(1), one Na(2), one Na(3), and one U(2) atom. In the sixth I site, I(6) is bonded in a distorted T-shaped geometry to one Na(2), one Na(5), and one U(3) atom. In the seventh I site, I(7) is bonded in a T-shaped geometry to one Na(1), one Na(3), and one U(1) atom. In the eighth I site, I(8) is bonded in a distorted T-shaped geometry to one Na(2), one Na(3), and one U(2) atom. In the ninth I site, I(9) is bonded in a distorted T-shaped geometry to one Na(2), one Na(5), and one U(2) atom. In the tenth I site, I(10) is bonded in a distorted T-shaped geometry to one Na(2), one Na(5), and one U(3) atom. In the eleventh I site, I(11) is bonded in a distorted T-shaped geometry to one Na(4), one Na(5), and one U(3) atom. In the twelfth I site, I(12) is bonded in a distorted T-shaped geometry to one Na(4), one Na(6), and one U(1) atom. In the thirteenth I site, I(13) is bonded in a distorted T-shaped geometry to one Na(2), one Na(5), and one U(2) atom. In the fourteenth I site, I(14) is bonded in a distorted T-shaped geometry to one Na(4), one Na(5), and one U(3) atom. In the fifteenth I site, I(15) is bonded in a distorted T-shaped geometry to one Na(4), one Na(6), and one U(3) atom. In the sixteenth I site, I(16) is bonded in a distorted T-shaped geometry to one Na(4), one Na(6), and one U(1) atom. In the seventeenth I site, I(17) is bonded in an L-shaped geometry to one Na(6) and one U(1) atom. In the eighteenth I site, I(18) is bonded in a distorted T-shaped geometry to one Na(4), one Na(6), and one U(3) atom. is represented by the CIF card [CIF]
data_Na2UI6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.961
_cell_length_b   8.761
_cell_length_c   19.811
_cell_angle_alpha   94.581
_cell_angle_beta   89.924
_cell_angle_gamma   116.965
_symmetry_Int_Tables_number   1
_cell_volume   1226.495
_cell_formula_units_Z   3
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
  Na  Na0  1  0.667  0.330  0.836  1.0
  Na  Na1  1  0.756  0.510  0.561  1.0
  Na  Na2  1  0.916  0.829  0.773  1.0
  Na  Na3  1  0.088  0.175  0.227  1.0
  Na  Na4  1  0.245  0.491  0.439  1.0
  Na  Na5  1  0.576  0.155  0.104  1.0
  U  U6  1  0.003  0.997  1.000  1.0
  U  U7  1  0.328  0.667  0.667  1.0
  U  U8  1  0.667  0.333  0.333  1.0
  I  I9  1  0.635  0.988  0.746  1.0
  I  I10  1  0.797  0.207  0.967  1.0
  I  I11  1  0.228  0.117  0.873  1.0
  I  I12  1  0.105  0.558  0.795  1.0
  I  I13  1  0.546  0.461  0.701  1.0
  I  I14  1  0.964  0.652  0.414  1.0
  I  I15  1  0.702  0.684  0.917  1.0
  I  I16  1  0.122  0.873  0.632  1.0
  I  I17  1  0.561  0.776  0.541  1.0
  I  I18  1  0.439  0.221  0.459  1.0
  I  I19  1  0.875  0.130  0.367  1.0
  I  I20  1  0.297  0.319  0.081  1.0
  I  I21  1  0.034  0.346  0.585  1.0
  I  I22  1  0.459  0.537  0.299  1.0
  I  I23  1  0.894  0.445  0.208  1.0
  I  I24  1  0.771  0.890  0.126  1.0
  I  I25  1  0.209  0.801  0.032  1.0
  I  I26  1  0.370  0.015  0.253  1.0
[/CIF]
.
The crystal structure described by Na2UI6 crystallizes in the triclinic P1 space group. There are six inequivalent Na sites. In the first Na site, Na(1) is bonded to one I(1), one I(2), one I(3), one I(4), one I(5), and one I(7) atom to form NaI6 octahedra that share  a cornercorner with one Na(2)I6 octahedra,  a cornercorner with one Na(6)I6 octahedra, corners with two equivalent Na(3)I6 octahedra, corners with three equivalent U(1)I6 octahedra, corners with three equivalent U(2)I6 octahedra, and  a faceface with one Na(3)I6 octahedra. The corner-sharing octahedral tilt angles range from 41-59°. In the second Na site, Na(2) is bonded to one I(10), one I(13), one I(5), one I(6), one I(8), and one I(9) atom to form NaI6 octahedra that share  a cornercorner with one Na(1)I6 octahedra,  an edgeedge with one Na(3)I6 octahedra,  an edgeedge with one U(3)I6 octahedra, edges with two equivalent Na(5)I6 octahedra, and edges with two equivalent U(2)I6 octahedra. The corner-sharing octahedral tilt angles are 56°. In the third Na site, Na(3) is bonded to one I(1), one I(3), one I(4), one I(5), one I(7), and one I(8) atom to form NaI6 octahedra that share corners with two equivalent Na(1)I6 octahedra,  an edgeedge with one Na(2)I6 octahedra,  an edgeedge with one U(1)I6 octahedra, edges with two equivalent U(2)I6 octahedra, and  a faceface with one Na(1)I6 octahedra. The corner-sharing octahedral tilt angles range from 56-58°. In the fourth Na site, Na(4) is bonded to one I(11), one I(12), one I(14), one I(15), one I(16), and one I(18) atom to form NaI6 octahedra that share  an edgeedge with one Na(5)I6 octahedra,  an edgeedge with one U(1)I6 octahedra, edges with two equivalent Na(6)I6 octahedra, and edges with two equivalent U(3)I6 octahedra. In the fifth Na site, Na(5) is bonded to one I(10), one I(11), one I(13), one I(14), one I(6), and one I(9) atom to form NaI6 octahedra that share  an edgeedge with one Na(4)I6 octahedra,  an edgeedge with one U(2)I6 octahedra, edges with two equivalent Na(2)I6 octahedra, and edges with two equivalent U(3)I6 octahedra. In the sixth Na site, Na(6) is bonded to one I(12), one I(15), one I(16), one I(17), one I(18), and one I(2) atom to form NaI6 octahedra that share  a cornercorner with one Na(1)I6 octahedra,  an edgeedge with one U(3)I6 octahedra, edges with two equivalent Na(4)I6 octahedra, and edges with two equivalent U(1)I6 octahedra. The corner-sharing octahedral tilt angles are 59°. There are three inequivalent U sites. In the first U site, U(1) is bonded to one I(12), one I(16), one I(17), one I(2), one I(3), and one I(7) atom to form UI6 octahedra that share corners with three equivalent Na(1)I6 octahedra,  an edgeedge with one Na(3)I6 octahedra,  an edgeedge with one Na(4)I6 octahedra, and edges with two equivalent Na(6)I6 octahedra. The corner-sharing octahedral tilt angles range from 41-43°. In the second U site, U(2) is bonded to one I(1), one I(13), one I(4), one I(5), one I(8), and one I(9) atom to form UI6 octahedra that share corners with three equivalent Na(1)I6 octahedra,  an edgeedge with one Na(5)I6 octahedra, edges with two equivalent Na(2)I6 octahedra, and edges with two equivalent Na(3)I6 octahedra. The corner-sharing octahedral tilt angles range from 41-42°. In the third U site, U(3) is bonded to one I(10), one I(11), one I(14), one I(15), one I(18), and one I(6) atom to form UI6 octahedra that share  an edgeedge with one Na(2)I6 octahedra,  an edgeedge with one Na(6)I6 octahedra, edges with two equivalent Na(4)I6 octahedra, and edges with two equivalent Na(5)I6 octahedra. There are eighteen inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(3), and one U(2) atom. In the second I site, I(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(6), and one U(1) atom. In the third I site, I(3) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(3), and one U(1) atom. In the fourth I site, I(4) is bonded in a T-shaped geometry to one Na(1), one Na(3), and one U(2) atom. In the fifth I site, I(5) is bonded in a rectangular see-saw-like geometry to one Na(1), one Na(2), one Na(3), and one U(2) atom. In the sixth I site, I(6) is bonded in a distorted T-shaped geometry to one Na(2), one Na(5), and one U(3) atom. In the seventh I site, I(7) is bonded in a T-shaped geometry to one Na(1), one Na(3), and one U(1) atom. In the eighth I site, I(8) is bonded in a distorted T-shaped geometry to one Na(2), one Na(3), and one U(2) atom. In the ninth I site, I(9) is bonded in a distorted T-shaped geometry to one Na(2), one Na(5), and one U(2) atom. In the tenth I site, I(10) is bonded in a distorted T-shaped geometry to one Na(2), one Na(5), and one U(3) atom. In the eleventh I site, I(11) is bonded in a distorted T-shaped geometry to one Na(4), one Na(5), and one U(3) atom. In the twelfth I site, I(12) is bonded in a distorted T-shaped geometry to one Na(4), one Na(6), and one U(1) atom. In the thirteenth I site, I(13) is bonded in a distorted T-shaped geometry to one Na(2), one Na(5), and one U(2) atom. In the fourteenth I site, I(14) is bonded in a distorted T-shaped geometry to one Na(4), one Na(5), and one U(3) atom. In the fifteenth I site, I(15) is bonded in a distorted T-shaped geometry to one Na(4), one Na(6), and one U(3) atom. In the sixteenth I site, I(16) is bonded in a distorted T-shaped geometry to one Na(4), one Na(6), and one U(1) atom. In the seventeenth I site, I(17) is bonded in an L-shaped geometry to one Na(6) and one U(1) atom. In the eighteenth I site, I(18) is bonded in a distorted T-shaped geometry to one Na(4), one Na(6), and one U(3) atom. is represented by the CIF card [CIF]
data_Na2UI6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.961
_cell_length_b   8.761
_cell_length_c   19.811
_cell_angle_alpha   94.581
_cell_angle_beta   89.924
_cell_angle_gamma   116.965
_symmetry_Int_Tables_number   1
_cell_volume   1226.495
_cell_formula_units_Z   3
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
  Na  Na0  1  0.667  0.330  0.836  1.0
  Na  Na1  1  0.756  0.510  0.561  1.0
  Na  Na2  1  0.916  0.829  0.773  1.0
  Na  Na3  1  0.088  0.175  0.227  1.0
  Na  Na4  1  0.245  0.491  0.439  1.0
  Na  Na5  1  0.576  0.155  0.104  1.0
  U  U6  1  0.003  0.997  1.000  1.0
  U  U7  1  0.328  0.667  0.667  1.0
  U  U8  1  0.667  0.333  0.333  1.0
  I  I9  1  0.635  0.988  0.746  1.0
  I  I10  1  0.797  0.207  0.967  1.0
  I  I11  1  0.228  0.117  0.873  1.0
  I  I12  1  0.105  0.558  0.795  1.0
  I  I13  1  0.546  0.461  0.701  1.0
  I  I14  1  0.964  0.652  0.414  1.0
  I  I15  1  0.702  0.684  0.917  1.0
  I  I16  1  0.122  0.873  0.632  1.0
  I  I17  1  0.561  0.776  0.541  1.0
  I  I18  1  0.439  0.221  0.459  1.0
  I  I19  1  0.875  0.130  0.367  1.0
  I  I20  1  0.297  0.319  0.081  1.0
  I  I21  1  0.034  0.346  0.585  1.0
  I  I22  1  0.459  0.537  0.299  1.0
  I  I23  1  0.894  0.445  0.208  1.0
  I  I24  1  0.771  0.890  0.126  1.0
  I  I25  1  0.209  0.801  0.032  1.0
  I  I26  1  0.370  0.015  0.253  1.0
[/CIF]
.