data_Na2CuO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.67
_cell_length_b   5.67
_cell_length_c   5.67
_cell_angle_alpha   149.31
_cell_angle_beta   132.96
_cell_angle_gamma   57.22
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2CuO2
_chemical_formula_sum   'Na2 Cu1 O2'
_cell_volume   67.68
_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  0.0  0.0  0.86  1.0
  Na  Na1  1  0.0  0.0  0.1  1.0
  Cu  Cu2  1  0.0  0.0  0.0  1.0
  O  O3  1  0.0  0.26  0.66  1.0
  O  O4  1  0.5  0.0  0.32  1.0

data_Na2CuO2
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.0
_cell_length_b   4.53
_cell_length_c   5.67
_cell_angle_alpha   113.52
_cell_angle_beta   105.35
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2CuO2
_chemical_formula_sum   'Na2 Cu1 O2'
_cell_volume   67.68
_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  0.14  0.14  0.14  1.0
  Na  Na1  1  0.9  0.9  0.9  1.0
  Cu  Cu2  1  0.0  0.0  0.0  1.0
  O  O3  1  0.18  0.68  0.18  1.0
  O  O4  1  0.34  0.6  0.6  1.0

Na Na Cu O O
Na2CuO2 crystallizes in the triclinic P1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted single-bond geometry to one Cu(1), one O(1), and two equivalent O(2) atoms. The Na(1)-Cu(1) bond length is 0.82 Å. The Na(1)-O(1) bond length is 2.51 Å. There is one shorter (2.19 Å) and one longer (2.35 Å) Na(1)-O(2) bond length. In the second Na site, Na(2) is bonded in a distorted single-bond geometry to one Cu(1), one O(2), and two equivalent O(1) atoms. The Na(2)-Cu(1) bond length is 0.59 Å. The Na(2)-O(2) bond length is 2.20 Å. There is one shorter (2.02 Å) and one longer (2.39 Å) Na(2)-O(1) bond length. Cu(1) is bonded in a linear geometry to one Na(1), one Na(2), and one O(2) atom. The Cu(1)-O(2) bond length is 2.08 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(1) and two equivalent Na(2) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), two equivalent Na(1), and one Cu(1) atom.