data_NaNi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.18
_cell_length_b   6.18
_cell_length_c   6.1
_cell_angle_alpha   104.57
_cell_angle_beta   104.57
_cell_angle_gamma   24.04
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaNi2
_chemical_formula_sum   'Na2 Ni4'
_cell_volume   91.61
_cell_formula_units_Z   2
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  0.43  0.0  0.31  1.0
  Na  Na1  1  0.08  0.0  0.58  1.0
  Ni  Ni2  1  0.3  0.0  0.07  1.0
  Ni  Ni3  1  0.97  0.0  0.01  1.0
  Ni  Ni4  1  0.54  0.0  0.89  1.0
  Ni  Ni5  1  0.21  0.0  0.83  1.0

data_NaNi2
_symmetry_space_group_name_H-M   P-1
_cell_length_a   2.57
_cell_length_b   6.1
_cell_length_c   6.18
_cell_angle_alpha   104.57
_cell_angle_beta   102.02
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   NaNi2
_chemical_formula_sum   'Na2 Ni4'
_cell_volume   91.61
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-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  2  0.0  0.13  0.83  1.0
  Ni  Ni1  2  0.0  0.38  0.96  1.0
  Ni  Ni2  2  0.0  0.44  0.29  1.0

Na Na Ni Ni Ni Ni
Na Na Ni Ni Ni Ni 0 2 o o o 1 5 o o o 2 5 o o - 2 3 - o o 2 4 o o - 3 5 + o - 4 5 o o o 
NaNi2 crystallizes in the triclinic P-1 space group. Na(1) is bonded in a single-bond geometry to one Ni(1) and two equivalent Ni(2) atoms. The Na(1)-Ni(1) bond length is 1.49 Å. There is one shorter (2.87 Å) and one longer (3.38 Å) Na(1)-Ni(2) bond length. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a distorted single-bond geometry to one Na(1) and two equivalent Ni(2) atoms. There is one shorter (1.99 Å) and one longer (2.10 Å) Ni(1)-Ni(2) bond length. In the second Ni site, Ni(2) is bonded in a 7-coordinate geometry to two equivalent Na(1), two equivalent Ni(1), and three equivalent Ni(2) atoms. There is one shorter (2.54 Å) and two longer (2.57 Å) Ni(2)-Ni(2) bond lengths.