The structure described by Na2U2O7 crystallizes in the monoclinic Pm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(6), two equivalent O(1), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded in a body-centered cubic geometry to one O(1), one O(3), one O(5), one O(7), two equivalent O(2), and two equivalent O(4) atoms. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(6), two equivalent O(5), and two equivalent O(7) atoms. In the second U site, U(2) is bonded to one O(1), one O(3), one O(5), one O(7), and two equivalent O(6) atoms to form distorted corner-sharing UO6 octahedra. The corner-sharing octahedral tilt angles are 43°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one U(2) atom. In the second O site, O(2) is bonded to one Na(1), two equivalent Na(2), and one U(1) atom to form distorted ONa3U tetrahedra that share corners with two equivalent O(2)Na3U tetrahedra, corners with four equivalent O(4)Na3U tetrahedra, corners with two equivalent O(6)NaU3 trigonal pyramids, corners with four equivalent O(7)NaU3 trigonal pyramids,  an edgeedge with one O(4)Na3U tetrahedra, edges with two equivalent O(3)Na3U tetrahedra, and edges with two equivalent O(5)NaU3 trigonal pyramids. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), and one U(2) atom to form distorted ONa3U tetrahedra that share corners with two equivalent O(3)Na3U tetrahedra, corners with four equivalent O(4)Na3U tetrahedra, corners with two equivalent O(5)NaU3 trigonal pyramids, edges with two equivalent O(2)Na3U tetrahedra,  an edgeedge with one O(7)NaU3 trigonal pyramid, and edges with two equivalent O(6)NaU3 trigonal pyramids. In the fourth O site, O(4) is bonded to one Na(1), two equivalent Na(2), and one U(1) atom to form distorted ONa3U tetrahedra that share corners with two equivalent O(4)Na3U tetrahedra, corners with four equivalent O(2)Na3U tetrahedra, corners with four equivalent O(3)Na3U tetrahedra, corners with four equivalent O(5)NaU3 trigonal pyramids,  an edgeedge with one O(2)Na3U tetrahedra,  an edgeedge with one O(6)NaU3 trigonal pyramid, and edges with two equivalent O(7)NaU3 trigonal pyramids. In the fifth O site, O(5) is bonded to one Na(2), one U(2), and two equivalent U(1) atoms to form distorted ONaU3 trigonal pyramids that share corners with two equivalent O(3)Na3U tetrahedra, corners with four equivalent O(4)Na3U tetrahedra, corners with two equivalent O(5)NaU3 trigonal pyramids, corners with four equivalent O(7)NaU3 trigonal pyramids, edges with two equivalent O(2)Na3U tetrahedra,  an edgeedge with one O(7)NaU3 trigonal pyramid, and edges with two equivalent O(6)NaU3 trigonal pyramids. In the sixth O site, O(6) is bonded to one Na(1), one U(1), and two equivalent U(2) atoms to form distorted ONaU3 trigonal pyramids that share corners with two equivalent O(2)Na3U tetrahedra, corners with two equivalent O(6)NaU3 trigonal pyramids, corners with four equivalent O(7)NaU3 trigonal pyramids,  an edgeedge with one O(4)Na3U tetrahedra, edges with two equivalent O(3)Na3U tetrahedra, and edges with two equivalent O(5)NaU3 trigonal pyramids. In the seventh O site, O(7) is bonded to one Na(2), one U(2), and two equivalent U(1) atoms to form distorted ONaU3 trigonal pyramids that share corners with four equivalent O(2)Na3U tetrahedra, corners with two equivalent O(7)NaU3 trigonal pyramids, corners with four equivalent O(5)NaU3 trigonal pyramids, corners with four equivalent O(6)NaU3 trigonal pyramids,  an edgeedge with one O(3)Na3U tetrahedra, edges with two equivalent O(4)Na3U tetrahedra, and  an edgeedge with one O(5)NaU3 trigonal pyramid. is represented by the CIF file [CIF]
data_Na2U2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.983
_cell_length_b   6.498
_cell_length_c   6.908
_cell_angle_alpha   69.551
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   167.536
_cell_formula_units_Z   1
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  0.000  0.509  0.499  1.0
  Na  Na1  1  0.500  0.501  0.996  1.0
  U  U2  1  0.000  0.999  0.015  1.0
  U  U3  1  0.500  0.987  0.490  1.0
  O  O4  1  0.500  0.297  0.411  1.0
  O  O5  1  0.000  0.304  0.886  1.0
  O  O6  1  0.500  0.674  0.593  1.0
  O  O7  1  0.000  0.692  0.117  1.0
  O  O8  1  0.500  0.043  0.148  1.0
  O  O9  1  0.000  0.960  0.388  1.0
  O  O10  1  0.500  0.963  0.815  1.0
[/CIF]
.
The structure described by Na2U2O7 crystallizes in the monoclinic Pm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(6), two equivalent O(1), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded in a body-centered cubic geometry to one O(1), one O(3), one O(5), one O(7), two equivalent O(2), and two equivalent O(4) atoms. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(6), two equivalent O(5), and two equivalent O(7) atoms. In the second U site, U(2) is bonded to one O(1), one O(3), one O(5), one O(7), and two equivalent O(6) atoms to form distorted corner-sharing UO6 octahedra. The corner-sharing octahedral tilt angles are 43°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one U(2) atom. In the second O site, O(2) is bonded to one Na(1), two equivalent Na(2), and one U(1) atom to form distorted ONa3U tetrahedra that share corners with two equivalent O(2)Na3U tetrahedra, corners with four equivalent O(4)Na3U tetrahedra, corners with two equivalent O(6)NaU3 trigonal pyramids, corners with four equivalent O(7)NaU3 trigonal pyramids,  an edgeedge with one O(4)Na3U tetrahedra, edges with two equivalent O(3)Na3U tetrahedra, and edges with two equivalent O(5)NaU3 trigonal pyramids. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), and one U(2) atom to form distorted ONa3U tetrahedra that share corners with two equivalent O(3)Na3U tetrahedra, corners with four equivalent O(4)Na3U tetrahedra, corners with two equivalent O(5)NaU3 trigonal pyramids, edges with two equivalent O(2)Na3U tetrahedra,  an edgeedge with one O(7)NaU3 trigonal pyramid, and edges with two equivalent O(6)NaU3 trigonal pyramids. In the fourth O site, O(4) is bonded to one Na(1), two equivalent Na(2), and one U(1) atom to form distorted ONa3U tetrahedra that share corners with two equivalent O(4)Na3U tetrahedra, corners with four equivalent O(2)Na3U tetrahedra, corners with four equivalent O(3)Na3U tetrahedra, corners with four equivalent O(5)NaU3 trigonal pyramids,  an edgeedge with one O(2)Na3U tetrahedra,  an edgeedge with one O(6)NaU3 trigonal pyramid, and edges with two equivalent O(7)NaU3 trigonal pyramids. In the fifth O site, O(5) is bonded to one Na(2), one U(2), and two equivalent U(1) atoms to form distorted ONaU3 trigonal pyramids that share corners with two equivalent O(3)Na3U tetrahedra, corners with four equivalent O(4)Na3U tetrahedra, corners with two equivalent O(5)NaU3 trigonal pyramids, corners with four equivalent O(7)NaU3 trigonal pyramids, edges with two equivalent O(2)Na3U tetrahedra,  an edgeedge with one O(7)NaU3 trigonal pyramid, and edges with two equivalent O(6)NaU3 trigonal pyramids. In the sixth O site, O(6) is bonded to one Na(1), one U(1), and two equivalent U(2) atoms to form distorted ONaU3 trigonal pyramids that share corners with two equivalent O(2)Na3U tetrahedra, corners with two equivalent O(6)NaU3 trigonal pyramids, corners with four equivalent O(7)NaU3 trigonal pyramids,  an edgeedge with one O(4)Na3U tetrahedra, edges with two equivalent O(3)Na3U tetrahedra, and edges with two equivalent O(5)NaU3 trigonal pyramids. In the seventh O site, O(7) is bonded to one Na(2), one U(2), and two equivalent U(1) atoms to form distorted ONaU3 trigonal pyramids that share corners with four equivalent O(2)Na3U tetrahedra, corners with two equivalent O(7)NaU3 trigonal pyramids, corners with four equivalent O(5)NaU3 trigonal pyramids, corners with four equivalent O(6)NaU3 trigonal pyramids,  an edgeedge with one O(3)Na3U tetrahedra, edges with two equivalent O(4)Na3U tetrahedra, and  an edgeedge with one O(5)NaU3 trigonal pyramid. is represented by the CIF file [CIF]
data_Na2U2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.983
_cell_length_b   6.498
_cell_length_c   6.908
_cell_angle_alpha   69.551
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   167.536
_cell_formula_units_Z   1
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  0.000  0.509  0.499  1.0
  Na  Na1  1  0.500  0.501  0.996  1.0
  U  U2  1  0.000  0.999  0.015  1.0
  U  U3  1  0.500  0.987  0.490  1.0
  O  O4  1  0.500  0.297  0.411  1.0
  O  O5  1  0.000  0.304  0.886  1.0
  O  O6  1  0.500  0.674  0.593  1.0
  O  O7  1  0.000  0.692  0.117  1.0
  O  O8  1  0.500  0.043  0.148  1.0
  O  O9  1  0.000  0.960  0.388  1.0
  O  O10  1  0.500  0.963  0.815  1.0
[/CIF]
.