data_NbSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.41
_cell_length_b   3.41
_cell_length_c   5.46
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NbSi
_chemical_formula_sum   'Nb2 Si2'
_cell_volume   63.46
_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
  Nb  Nb0  1  0.7  0.0  0.7  1.0
  Nb  Nb1  1  0.0  0.7  0.76  1.0
  Si  Si2  1  0.7  0.0  0.02  1.0
  Si  Si3  1  0.0  0.7  0.44  1.0

data_NbSi
_symmetry_space_group_name_H-M   C2/m
_cell_length_a   4.82
_cell_length_b   4.82
_cell_length_c   5.46
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   12
_chemical_formula_structural   NbSi
_chemical_formula_sum   'Nb4 Si4'
_cell_volume   126.92
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-x, -y, -z'
  3  '-x, y, -z'
  4  'x, -y, z'
  5  'x+1/2, y+1/2, z'
  6  '-x+1/2, -y+1/2, -z'
  7  '-x+1/2, y+1/2, -z'
  8  '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
  Nb  Nb0  4  0.15  0.0  0.53  1.0
  Si  Si1  4  0.15  0.0  0.21  1.0

Nb Nb Si Si
NbSi is gamma CuTi structured and crystallizes in the monoclinic C2/m space group. The structure is zero-dimensional and consists of two NbSi clusters. Nb(1) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Si(1) atoms. The Nb(1)-Nb(1) bond length is 1.46 Å. There is one shorter (1.74 Å) and one longer (2.02 Å) Nb(1)-Si(1) bond length. Si(1) is bonded in a 2-coordinate geometry to two equivalent Nb(1) atoms.