The material structure described by Na2UI6 is zeta iron carbide-derived structured and crystallizes in the triclinic P1 space group. There are eight 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(8)I6 octahedra, corners with two equivalent Na(2)I6 octahedra, corners with three equivalent U(1)I6 octahedra, corners with three equivalent U(2)I6 octahedra, and  a faceface with one Na(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 39-65°. In the second Na site, Na(2) 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  a cornercorner with one Na(3)I6 octahedra, corners with two equivalent Na(1)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 53-65°. In the third Na site, Na(3) is bonded to one I(10), one I(11), one I(13), one I(6), one I(8), and one I(9) atom to form NaI6 octahedra that share  a cornercorner with one Na(2)I6 octahedra, corners with two equivalent Na(4)I6 octahedra, corners with three equivalent U(2)I6 octahedra, corners with three equivalent U(3)I6 octahedra, and  a faceface with one Na(4)I6 octahedra. The corner-sharing octahedral tilt angles range from 38-65°. In the fourth Na site, Na(4) 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  a cornercorner with one Na(5)I6 octahedra, corners with two equivalent Na(3)I6 octahedra,  an edgeedge with one U(2)I6 octahedra, edges with two equivalent U(3)I6 octahedra, and  a faceface with one Na(3)I6 octahedra. The corner-sharing octahedral tilt angles range from 54-65°. In the fifth Na site, Na(5) is bonded to one I(12), one I(14), one I(15), one I(16), one I(17), and one I(19) atom to form NaI6 octahedra that share  a cornercorner with one Na(4)I6 octahedra,  a cornercorner with one Na(6)I6 octahedra, corners with two equivalent Na(7)I6 octahedra, corners with three equivalent U(3)I6 octahedra, corners with three equivalent U(4)I6 octahedra, and  a faceface with one Na(7)I6 octahedra. The corner-sharing octahedral tilt angles range from 40-65°. In the sixth Na site, Na(6) is bonded to one I(17), one I(18), one I(20), one I(21), one I(22), and one I(24) atom to form NaI6 octahedra that share  a cornercorner with one Na(5)I6 octahedra,  an edgeedge with one Na(7)I6 octahedra,  an edgeedge with one U(1)I6 octahedra, edges with two equivalent Na(8)I6 octahedra, and edges with two equivalent U(4)I6 octahedra. The corner-sharing octahedral tilt angles are 62°. In the seventh Na site, Na(7) is bonded to one I(12), one I(15), one I(16), one I(17), one I(19), and one I(20) atom to form NaI6 octahedra that share corners with two equivalent Na(5)I6 octahedra,  an edgeedge with one Na(6)I6 octahedra,  an edgeedge with one U(3)I6 octahedra, edges with two equivalent U(4)I6 octahedra, and  a faceface with one Na(5)I6 octahedra. The corner-sharing octahedral tilt angles range from 54-57°. In the eighth Na site, Na(8) is bonded to one I(18), one I(2), one I(21), one I(22), one I(23), and one I(24) atom to form NaI6 octahedra that share  a cornercorner with one Na(1)I6 octahedra,  an edgeedge with one U(4)I6 octahedra, edges with two equivalent Na(6)I6 octahedra, and edges with two equivalent U(1)I6 octahedra. The corner-sharing octahedral tilt angles are 65°. There are four inequivalent U sites. In the first U site, U(1) is bonded to one I(18), one I(2), one I(22), one I(23), 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(2)I6 octahedra,  an edgeedge with one Na(6)I6 octahedra, and edges with two equivalent Na(8)I6 octahedra. The corner-sharing octahedral tilt angles range from 40-43°. 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, corners with three equivalent Na(3)I6 octahedra,  an edgeedge with one Na(4)I6 octahedra, and edges with two equivalent Na(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 39-43°. In the third U site, U(3) is bonded to one I(10), one I(11), one I(14), one I(15), one I(19), and one I(6) atom to form UI6 octahedra that share corners with three equivalent Na(3)I6 octahedra, corners with three equivalent Na(5)I6 octahedra,  an edgeedge with one Na(7)I6 octahedra, and edges with two equivalent Na(4)I6 octahedra. The corner-sharing octahedral tilt angles range from 38-43°. In the fourth U site, U(4) is bonded to one I(12), one I(16), one I(17), one I(20), one I(21), and one I(24) atom to form UI6 octahedra that share corners with three equivalent Na(5)I6 octahedra,  an edgeedge with one Na(8)I6 octahedra, edges with two equivalent Na(6)I6 octahedra, and edges with two equivalent Na(7)I6 octahedra. The corner-sharing octahedral tilt angles range from 40-43°. There are twenty-four inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), 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(8), and one U(1) atom. In the third I site, I(3) is bonded in a distorted T-shaped geometry to one Na(1), one Na(2), and one U(1) atom. In the fourth I site, I(4) is bonded in a distorted T-shaped geometry to one Na(1), one Na(2), and one U(2) atom. In the fifth I site, I(5) is bonded in a T-shaped geometry to one Na(1), one Na(2), and one U(2) atom. In the sixth I site, I(6) is bonded in a distorted trigonal planar geometry to one Na(3), one Na(4), and one U(3) atom. In the seventh I site, I(7) is bonded in a distorted T-shaped geometry to one Na(1), one Na(2), and one U(1) atom. In the eighth I site, I(8) is bonded in a distorted trigonal planar 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 trigonal planar geometry to one Na(3), one Na(4), and one U(2) atom. In the tenth I site, I(10) is bonded in a distorted T-shaped geometry to one Na(3), one Na(4), and one U(3) atom. In the eleventh I site, I(11) is bonded in a T-shaped geometry to one Na(3), one Na(4), and one U(3) atom. In the twelfth I site, I(12) is bonded in a distorted trigonal planar geometry to one Na(5), one Na(7), and one U(4) atom. In the thirteenth I site, I(13) is bonded in a distorted T-shaped geometry to one Na(3), one Na(4), and one U(2) atom. In the fourteenth I site, I(14) is bonded in a distorted trigonal planar 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 trigonal planar geometry to one Na(5), one Na(7), and one U(3) atom. In the sixteenth I site, I(16) is bonded in a distorted T-shaped geometry to one Na(5), one Na(7), and one U(4) atom. In the seventeenth I site, I(17) is bonded in a rectangular see-saw-like geometry to one Na(5), one Na(6), one Na(7), and one U(4) atom. In the eighteenth I site, I(18) is bonded in a distorted T-shaped geometry to one Na(6), one Na(8), and one U(1) atom. In the nineteenth I site, I(19) is bonded in a distorted T-shaped geometry to one Na(5), one Na(7), and one U(3) atom. In the twentieth I site, I(20) is bonded in a distorted T-shaped geometry to one Na(6), one Na(7), and one U(4) atom. In the twenty-first I site, I(21) is bonded in a distorted T-shaped geometry to one Na(6), one Na(8), and one U(4) atom. In the twenty-second I site, I(22) is bonded in a distorted T-shaped geometry to one Na(6), one Na(8), and one U(1) atom. In the twenty-third I site, I(23) is bonded in an L-shaped geometry to one Na(8) and one U(1) atom. In the twenty-fourth I site, I(24) is bonded in a distorted T-shaped geometry to one Na(6), one Na(8), and one U(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2UI6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.139
_cell_length_b   9.186
_cell_length_c   34.765
_cell_angle_alpha   51.453
_cell_angle_beta   53.280
_cell_angle_gamma   54.118
_symmetry_Int_Tables_number   1
_cell_volume   1720.254
_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
  Na  Na0  1  0.496  0.498  0.125  1.0
  Na  Na1  1  0.681  0.675  0.171  1.0
  Na  Na2  1  0.496  0.497  0.375  1.0
  Na  Na3  1  0.680  0.674  0.422  1.0
  Na  Na4  1  0.495  0.501  0.624  1.0
  Na  Na5  1  0.317  0.327  0.830  1.0
  Na  Na6  1  0.683  0.679  0.670  1.0
  Na  Na7  1  0.678  0.670  0.921  1.0
  U  U8  1  0.995  0.002  0.000  1.0
  U  U9  1  0.001  0.002  0.249  1.0
  U  U10  1  0.001  0.002  0.499  1.0
  U  U11  1  0.009  0.997  0.749  1.0
  I  I12  1  0.091  0.372  0.192  1.0
  I  I13  1  0.363  0.775  0.023  1.0
  I  I14  1  0.767  0.086  0.098  1.0
  I  I15  1  0.248  0.902  0.153  1.0
  I  I16  1  0.641  0.239  0.224  1.0
  I  I17  1  0.090  0.372  0.441  1.0
  I  I18  1  0.897  0.635  0.061  1.0
  I  I19  1  0.363  0.776  0.273  1.0
  I  I20  1  0.767  0.085  0.348  1.0
  I  I21  1  0.247  0.903  0.404  1.0
  I  I22  1  0.641  0.241  0.474  1.0
  I  I23  1  0.091  0.372  0.692  1.0
  I  I24  1  0.896  0.638  0.311  1.0
  I  I25  1  0.364  0.775  0.523  1.0
  I  I26  1  0.767  0.086  0.597  1.0
  I  I27  1  0.248  0.904  0.653  1.0
  I  I28  1  0.632  0.243  0.725  1.0
  I  I29  1  0.091  0.371  0.941  1.0
  I  I30  1  0.897  0.637  0.561  1.0
  I  I31  1  0.367  0.760  0.775  1.0
  I  I32  1  0.758  0.084  0.847  1.0
  I  I33  1  0.243  0.911  0.903  1.0
  I  I34  1  0.646  0.232  0.976  1.0
  I  I35  1  0.908  0.630  0.810  1.0
[/CIF]
.
The material structure described by Na2UI6 is zeta iron carbide-derived structured and crystallizes in the triclinic P1 space group. There are eight 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(8)I6 octahedra, corners with two equivalent Na(2)I6 octahedra, corners with three equivalent U(1)I6 octahedra, corners with three equivalent U(2)I6 octahedra, and  a faceface with one Na(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 39-65°. In the second Na site, Na(2) 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  a cornercorner with one Na(3)I6 octahedra, corners with two equivalent Na(1)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 53-65°. In the third Na site, Na(3) is bonded to one I(10), one I(11), one I(13), one I(6), one I(8), and one I(9) atom to form NaI6 octahedra that share  a cornercorner with one Na(2)I6 octahedra, corners with two equivalent Na(4)I6 octahedra, corners with three equivalent U(2)I6 octahedra, corners with three equivalent U(3)I6 octahedra, and  a faceface with one Na(4)I6 octahedra. The corner-sharing octahedral tilt angles range from 38-65°. In the fourth Na site, Na(4) 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  a cornercorner with one Na(5)I6 octahedra, corners with two equivalent Na(3)I6 octahedra,  an edgeedge with one U(2)I6 octahedra, edges with two equivalent U(3)I6 octahedra, and  a faceface with one Na(3)I6 octahedra. The corner-sharing octahedral tilt angles range from 54-65°. In the fifth Na site, Na(5) is bonded to one I(12), one I(14), one I(15), one I(16), one I(17), and one I(19) atom to form NaI6 octahedra that share  a cornercorner with one Na(4)I6 octahedra,  a cornercorner with one Na(6)I6 octahedra, corners with two equivalent Na(7)I6 octahedra, corners with three equivalent U(3)I6 octahedra, corners with three equivalent U(4)I6 octahedra, and  a faceface with one Na(7)I6 octahedra. The corner-sharing octahedral tilt angles range from 40-65°. In the sixth Na site, Na(6) is bonded to one I(17), one I(18), one I(20), one I(21), one I(22), and one I(24) atom to form NaI6 octahedra that share  a cornercorner with one Na(5)I6 octahedra,  an edgeedge with one Na(7)I6 octahedra,  an edgeedge with one U(1)I6 octahedra, edges with two equivalent Na(8)I6 octahedra, and edges with two equivalent U(4)I6 octahedra. The corner-sharing octahedral tilt angles are 62°. In the seventh Na site, Na(7) is bonded to one I(12), one I(15), one I(16), one I(17), one I(19), and one I(20) atom to form NaI6 octahedra that share corners with two equivalent Na(5)I6 octahedra,  an edgeedge with one Na(6)I6 octahedra,  an edgeedge with one U(3)I6 octahedra, edges with two equivalent U(4)I6 octahedra, and  a faceface with one Na(5)I6 octahedra. The corner-sharing octahedral tilt angles range from 54-57°. In the eighth Na site, Na(8) is bonded to one I(18), one I(2), one I(21), one I(22), one I(23), and one I(24) atom to form NaI6 octahedra that share  a cornercorner with one Na(1)I6 octahedra,  an edgeedge with one U(4)I6 octahedra, edges with two equivalent Na(6)I6 octahedra, and edges with two equivalent U(1)I6 octahedra. The corner-sharing octahedral tilt angles are 65°. There are four inequivalent U sites. In the first U site, U(1) is bonded to one I(18), one I(2), one I(22), one I(23), 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(2)I6 octahedra,  an edgeedge with one Na(6)I6 octahedra, and edges with two equivalent Na(8)I6 octahedra. The corner-sharing octahedral tilt angles range from 40-43°. 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, corners with three equivalent Na(3)I6 octahedra,  an edgeedge with one Na(4)I6 octahedra, and edges with two equivalent Na(2)I6 octahedra. The corner-sharing octahedral tilt angles range from 39-43°. In the third U site, U(3) is bonded to one I(10), one I(11), one I(14), one I(15), one I(19), and one I(6) atom to form UI6 octahedra that share corners with three equivalent Na(3)I6 octahedra, corners with three equivalent Na(5)I6 octahedra,  an edgeedge with one Na(7)I6 octahedra, and edges with two equivalent Na(4)I6 octahedra. The corner-sharing octahedral tilt angles range from 38-43°. In the fourth U site, U(4) is bonded to one I(12), one I(16), one I(17), one I(20), one I(21), and one I(24) atom to form UI6 octahedra that share corners with three equivalent Na(5)I6 octahedra,  an edgeedge with one Na(8)I6 octahedra, edges with two equivalent Na(6)I6 octahedra, and edges with two equivalent Na(7)I6 octahedra. The corner-sharing octahedral tilt angles range from 40-43°. There are twenty-four inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), 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(8), and one U(1) atom. In the third I site, I(3) is bonded in a distorted T-shaped geometry to one Na(1), one Na(2), and one U(1) atom. In the fourth I site, I(4) is bonded in a distorted T-shaped geometry to one Na(1), one Na(2), and one U(2) atom. In the fifth I site, I(5) is bonded in a T-shaped geometry to one Na(1), one Na(2), and one U(2) atom. In the sixth I site, I(6) is bonded in a distorted trigonal planar geometry to one Na(3), one Na(4), and one U(3) atom. In the seventh I site, I(7) is bonded in a distorted T-shaped geometry to one Na(1), one Na(2), and one U(1) atom. In the eighth I site, I(8) is bonded in a distorted trigonal planar 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 trigonal planar geometry to one Na(3), one Na(4), and one U(2) atom. In the tenth I site, I(10) is bonded in a distorted T-shaped geometry to one Na(3), one Na(4), and one U(3) atom. In the eleventh I site, I(11) is bonded in a T-shaped geometry to one Na(3), one Na(4), and one U(3) atom. In the twelfth I site, I(12) is bonded in a distorted trigonal planar geometry to one Na(5), one Na(7), and one U(4) atom. In the thirteenth I site, I(13) is bonded in a distorted T-shaped geometry to one Na(3), one Na(4), and one U(2) atom. In the fourteenth I site, I(14) is bonded in a distorted trigonal planar 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 trigonal planar geometry to one Na(5), one Na(7), and one U(3) atom. In the sixteenth I site, I(16) is bonded in a distorted T-shaped geometry to one Na(5), one Na(7), and one U(4) atom. In the seventeenth I site, I(17) is bonded in a rectangular see-saw-like geometry to one Na(5), one Na(6), one Na(7), and one U(4) atom. In the eighteenth I site, I(18) is bonded in a distorted T-shaped geometry to one Na(6), one Na(8), and one U(1) atom. In the nineteenth I site, I(19) is bonded in a distorted T-shaped geometry to one Na(5), one Na(7), and one U(3) atom. In the twentieth I site, I(20) is bonded in a distorted T-shaped geometry to one Na(6), one Na(7), and one U(4) atom. In the twenty-first I site, I(21) is bonded in a distorted T-shaped geometry to one Na(6), one Na(8), and one U(4) atom. In the twenty-second I site, I(22) is bonded in a distorted T-shaped geometry to one Na(6), one Na(8), and one U(1) atom. In the twenty-third I site, I(23) is bonded in an L-shaped geometry to one Na(8) and one U(1) atom. In the twenty-fourth I site, I(24) is bonded in a distorted T-shaped geometry to one Na(6), one Na(8), and one U(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2UI6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.139
_cell_length_b   9.186
_cell_length_c   34.765
_cell_angle_alpha   51.453
_cell_angle_beta   53.280
_cell_angle_gamma   54.118
_symmetry_Int_Tables_number   1
_cell_volume   1720.254
_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
  Na  Na0  1  0.496  0.498  0.125  1.0
  Na  Na1  1  0.681  0.675  0.171  1.0
  Na  Na2  1  0.496  0.497  0.375  1.0
  Na  Na3  1  0.680  0.674  0.422  1.0
  Na  Na4  1  0.495  0.501  0.624  1.0
  Na  Na5  1  0.317  0.327  0.830  1.0
  Na  Na6  1  0.683  0.679  0.670  1.0
  Na  Na7  1  0.678  0.670  0.921  1.0
  U  U8  1  0.995  0.002  0.000  1.0
  U  U9  1  0.001  0.002  0.249  1.0
  U  U10  1  0.001  0.002  0.499  1.0
  U  U11  1  0.009  0.997  0.749  1.0
  I  I12  1  0.091  0.372  0.192  1.0
  I  I13  1  0.363  0.775  0.023  1.0
  I  I14  1  0.767  0.086  0.098  1.0
  I  I15  1  0.248  0.902  0.153  1.0
  I  I16  1  0.641  0.239  0.224  1.0
  I  I17  1  0.090  0.372  0.441  1.0
  I  I18  1  0.897  0.635  0.061  1.0
  I  I19  1  0.363  0.776  0.273  1.0
  I  I20  1  0.767  0.085  0.348  1.0
  I  I21  1  0.247  0.903  0.404  1.0
  I  I22  1  0.641  0.241  0.474  1.0
  I  I23  1  0.091  0.372  0.692  1.0
  I  I24  1  0.896  0.638  0.311  1.0
  I  I25  1  0.364  0.775  0.523  1.0
  I  I26  1  0.767  0.086  0.597  1.0
  I  I27  1  0.248  0.904  0.653  1.0
  I  I28  1  0.632  0.243  0.725  1.0
  I  I29  1  0.091  0.371  0.941  1.0
  I  I30  1  0.897  0.637  0.561  1.0
  I  I31  1  0.367  0.760  0.775  1.0
  I  I32  1  0.758  0.084  0.847  1.0
  I  I33  1  0.243  0.911  0.903  1.0
  I  I34  1  0.646  0.232  0.976  1.0
  I  I35  1  0.908  0.630  0.810  1.0
[/CIF]
.