data_Na2TaCo
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.95
_cell_length_b   8.95
_cell_length_c   8.95
_cell_angle_alpha   160.88
_cell_angle_beta   155.35
_cell_angle_gamma   31.39
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2TaCo
_chemical_formula_sum   'Na2 Ta1 Co1'
_cell_volume   97.81
_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  Na1  1  0.0  0.91  0.92  1.0
  Na  Na2  1  0.49  0.0  0.69  1.0
  Ta  Ta3  1  0.0  0.0  0.61  1.0
  Co  Co0  1  0.0  0.0  0.0  1.0

data_Na2TaCo
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.97
_cell_length_b   3.82
_cell_length_c   8.95
_cell_angle_alpha   102.33
_cell_angle_beta   99.56
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2TaCo
_chemical_formula_sum   'Na2 Ta1 Co1'
_cell_volume   97.81
_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  0.08  0.99  0.99  1.0
  Na  Na1  1  0.8  0.31  0.8  1.0
  Ta  Ta2  1  0.39  0.39  0.39  1.0
  Co  Co3  1  0.0  0.0  0.0  1.0

Na Na Ta Co
Na Na Ta Co 0 3 o + + 0 1 o + + 0 1 - + o 0 2 o + o 1 3 o o o 1 3 + o + 1 2 o o o 2 2 o + + 2 3 o o + 
Na2TaCo crystallizes in the triclinic P1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a single-bond geometry to two equivalent Na(2) and one Co(1) atom. There is one shorter (2.35 Å) and one longer (2.81 Å) Na(1)-Na(2) bond length. The Na(1)-Co(1) bond length is 0.27 Å. In the second Na site, Na(2) is bonded in a 7-coordinate geometry to two equivalent Na(1), two equivalent Na(2), one Ta(1), and two equivalent Co(1) atoms. Both Na(2)-Na(2) bond lengths are 2.97 Å. The Na(2)-Ta(1) bond length is 3.74 Å. There is one shorter (2.38 Å) and one longer (2.87 Å) Na(2)-Co(1) bond length. Ta(1) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Ta(1), and one Co(1) atom. Both Ta(1)-Ta(1) bond lengths are 2.97 Å. The Ta(1)-Co(1) bond length is 3.46 Å. Co(1) is bonded in a single-bond geometry to one Na(1), two equivalent Na(2), and one Ta(1) atom.