data_CrNi3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.35
_cell_length_b   4.35
_cell_length_c   4.35
_cell_angle_alpha   132.5
_cell_angle_beta   132.5
_cell_angle_gamma   69.45
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CrNi3
_chemical_formula_sum   'Cr1 Ni3'
_cell_volume   43.94
_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
  Cr  Cr0  1  0.0  0.0  0.0  1.0
  Ni  Ni1  1  0.0  0.0  0.58  1.0
  Ni  Ni2  1  0.0  0.75  0.79  1.0
  Ni  Ni3  1  0.75  0.0  0.79  1.0

data_CrNi3
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.96
_cell_length_b   4.96
_cell_length_c   4.35
_cell_angle_alpha   90.0
_cell_angle_beta   124.72
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   CrNi3
_chemical_formula_sum   'Cr2 Ni6'
_cell_volume   87.88
_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
  Cr  Cr0  2  0.0  0.0  0.0  1.0
  Ni  Ni1  4  0.09  0.12  0.96  1.0
  Ni  Ni2  2  0.42  0.0  0.42  1.0

Cr Ni Ni Ni
Cr Ni Ni Ni 0 3 - o - 0 2 o - - 0 1 o o - 1 3 - o o 1 2 o - o 
Ni3Cr crystallizes in the monoclinic Cm space group. Cr(1) is bonded in a water-like geometry to two equivalent Ni(1) and two equivalent Ni(2) atoms. There is one shorter (1.84 Å) and one longer (2.51 Å) Cr(1)-Ni(1) bond length. Both Cr(1)-Ni(2) bond lengths are 0.82 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 6-coordinate geometry to two equivalent Cr(1) and four equivalent Ni(2) atoms. There are two shorter (1.83 Å) and two longer (2.74 Å) Ni(1)-Ni(2) bond lengths. In the second Ni site, Ni(2) is bonded in a single-bond geometry to one Cr(1) and two equivalent Ni(1) atoms.