data_NiAs
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.92
_cell_length_b   2.92
_cell_length_c   7.13
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   93.66
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NiAs
_chemical_formula_sum   'Ni2 As2'
_cell_volume   60.82
_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
  Ni  Ni2  1  0.0  0.07  0.35  1.0
  Ni  Ni3  1  0.0  0.93  0.78  1.0
  As  As0  1  0.0  0.07  0.5  1.0
  As  As1  1  0.0  0.93  0.63  1.0

data_NiAs
_symmetry_space_group_name_H-M   P-1
_cell_length_a   2.92
_cell_length_b   2.92
_cell_length_c   7.13
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   93.66
_symmetry_Int_Tables_number   2
_chemical_formula_structural   NiAs
_chemical_formula_sum   'Ni2 As2'
_cell_volume   60.82
_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
  Ni  Ni0  2  0.0  0.07  0.28  1.0
  As  As1  2  0.0  0.07  0.43  1.0

Ni Ni As As
NiAs crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one NiAs cluster. Ni(1) is bonded in a single-bond geometry to one As(1) atom. The Ni(1)-As(1) bond length is 1.06 Å. As(1) is bonded in a distorted bent 150 degrees geometry to one Ni(1) and one As(1) atom. The As(1)-As(1) bond length is 1.04 Å.