data_BaTa2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.52
_cell_length_b   3.52
_cell_length_c   7.9
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   BaTa2Se
_chemical_formula_sum   'Ba1 Ta2 Se1'
_cell_volume   97.73
_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  0.76  0.76  0.99  1.0
  Ta  Ta2  1  0.76  0.76  0.05  1.0
  Ta  Ta3  1  0.0  0.0  0.34  1.0
  Se  Se1  1  0.0  0.0  0.48  1.0

data_BaTa2Se
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.97
_cell_length_b   4.97
_cell_length_c   7.9
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   BaTa2Se
_chemical_formula_sum   'Ba2 Ta4 Se2'
_cell_volume   195.45
_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  2  0.26  0.5  0.99  1.0
  Ta  Ta1  2  0.0  0.0  0.34  1.0
  Ta  Ta2  2  0.26  0.5  0.05  1.0
  Se  Se3  2  0.0  0.0  0.48  1.0

Ba Ta Ta Se
Ba Ta Ta Se 0 1 o o + 2 3 o o o 
BaTaTaSe is alpha carbon monoxide-derived structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two selanylidenetantalum molecules and two BaTa clusters. In each BaTa cluster, Ba(1) is bonded in a single-bond geometry to one Ta(1) atom. The Ba(1)-Ta(1) bond length is 0.51 Å. Ta(1) is bonded in a single-bond geometry to one Ba(1) atom.