data_MnNb2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.31
_cell_length_b   3.31
_cell_length_c   5.66
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MnNb2Si
_chemical_formula_sum   'Mn1 Nb2 Si1'
_cell_volume   61.87
_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
  Mn  Mn0  1  0.65  0.65  0.13  1.0
  Nb  Nb1  1  0.0  0.0  0.61  1.0
  Nb  Nb2  1  0.65  0.65  0.54  1.0
  Si  Si3  1  0.0  0.0  0.88  1.0

data_MnNb2Si
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.67
_cell_length_b   4.67
_cell_length_c   5.66
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   MnNb2Si
_chemical_formula_sum   'Mn2 Nb4 Si2'
_cell_volume   123.73
_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
  Mn  Mn0  2  0.15  0.5  0.13  1.0
  Nb  Nb1  2  0.0  0.0  0.61  1.0
  Nb  Nb2  2  0.15  0.5  0.54  1.0
  Si  Si3  2  0.0  0.0  0.88  1.0

Mn Nb Nb Si
Mn Nb Nb Si 0 3 + + - 0 2 o o o 1 2 - - o 1 3 o o o 
Nb2MnSi crystallizes in the monoclinic Cm space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted single-bond geometry to one Nb(2) and one Si(1) atom. The Nb(1)-Nb(2) bond length is 1.68 Å. The Nb(1)-Si(1) bond length is 1.50 Å. In the second Nb site, Nb(2) is bonded in a 2-coordinate geometry to one Nb(1) and one Mn(1) atom. The Nb(2)-Mn(1) bond length is 2.31 Å. Mn(1) is bonded in a 4-coordinate geometry to one Nb(2) and three equivalent Si(1) atoms. There is one shorter (2.16 Å) and two longer (2.83 Å) Mn(1)-Si(1) bond lengths. Si(1) is bonded in a 2-coordinate geometry to one Nb(1) and three equivalent Mn(1) atoms.