data_Ba2NaSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.83
_cell_length_b   5.83
_cell_length_c   4.32
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ba2NaSe
_chemical_formula_sum   'Ba2 Na1 Se1'
_cell_volume   146.88
_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
  Ba  Ba0  1  0.91  0.0  0.16  1.0
  Ba  Ba1  1  0.0  0.91  0.16  1.0
  Na  Na2  1  0.0  0.0  0.0  1.0
  Se  Se3  1  0.91  0.91  0.0  1.0

data_Ba2NaSe
_symmetry_space_group_name_H-M   Cm
_cell_length_a   8.24
_cell_length_b   8.24
_cell_length_c   4.32
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Ba2NaSe
_chemical_formula_sum   'Ba4 Na2 Se2'
_cell_volume   293.76
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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
  Ba  Ba0  4  0.46  0.46  0.16  1.0
  Na  Na1  2  0.0  0.0  0.0  1.0
  Se  Se2  2  0.41  0.5  0.0  1.0

Ba Ba Na Se
Ba Ba Na Se 0 3 o - o 0 1 + - o 0 2 + o o 1 3 - o o 1 2 o + o 2 3 - - o 
NaBa2Se crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two NaBa2Se clusters. Na(1) is bonded in a single-bond geometry to one Se(1) atom. The Na(1)-Se(1) bond length is 0.70 Å. Ba(1) is bonded in a 2-coordinate geometry to one Ba(1) and one Se(1) atom. The Ba(1)-Ba(1) bond length is 0.70 Å. The Ba(1)-Se(1) bond length is 0.86 Å. Se(1) is bonded in a distorted single-bond geometry to one Na(1) and two equivalent Ba(1) atoms.