data_Na2Cr
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.38
_cell_length_b   3.38
_cell_length_c   7.73
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2Cr
_chemical_formula_sum   'Na2 Cr1'
_cell_volume   76.45
_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  0.69  0.98  0.26  1.0
  Na  Na2  1  0.0  0.95  0.47  1.0
  Cr  Cr0  1  0.0  0.0  0.0  1.0

data_Na2Cr
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.38
_cell_length_b   3.38
_cell_length_c   7.73
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2Cr
_chemical_formula_sum   'Na2 Cr1'
_cell_volume   76.45
_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  0.95  0.47  1.0
  Na  Na1  1  0.69  0.98  0.26  1.0
  Cr  Cr2  1  0.0  0.0  0.0  1.0

Na Na Cr
Na Na Cr 0 1 + o o 0 2 + + o 
Na2Cr crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one Na2Cr cluster. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 1-coordinate geometry to one Na(2) and one Cr(1) atom. The Na(1)-Na(2) bond length is 1.97 Å. The Na(1)-Cr(1) bond length is 2.23 Å. In the second Na site, Na(2) is bonded in a distorted single-bond geometry to one Na(1) atom. Cr(1) is bonded in a distorted single-bond geometry to one Na(1) atom.