data_Mg2NbSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.82
_cell_length_b   5.05
_cell_length_c   5.01
_cell_angle_alpha   90.0
_cell_angle_beta   96.51
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2NbSi
_chemical_formula_sum   'Mg2 Nb1 Si1'
_cell_volume   70.86
_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
  Mg  Mg0  1  0.14  0.52  0.73  1.0
  Mg  Mg1  1  0.11  0.52  0.24  1.0
  Nb  Nb2  1  0.13  0.0  0.49  1.0
  Si  Si3  1  0.0  0.0  0.0  1.0

data_Mg2NbSi
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.82
_cell_length_b   5.01
_cell_length_c   5.05
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   96.51
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2NbSi
_chemical_formula_sum   'Mg2 Nb1 Si1'
_cell_volume   70.86
_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
  Mg  Mg0  1  0.86  0.27  0.48  1.0
  Mg  Mg1  1  0.89  0.76  0.48  1.0
  Nb  Nb2  1  0.87  0.51  0.0  1.0
  Si  Si3  1  0.0  0.0  0.0  1.0

Mg Mg Nb Si
Mg Mg Nb Si 0 2 o o o 0 2 o + o 0 3 o o + 0 3 o + + 0 1 o o o 0 1 o o + 0 0 + o o 1 3 o o o 1 3 o + o 1 1 + o o 1 2 o o o 1 2 o + o 2 3 o o o 2 3 o o + 2 2 + o o 3 3 + o o 
Mg2NbSi crystallizes in the triclinic P1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Nb(1), and two equivalent Si(1) atoms to form a mixture of distorted edge and corner-sharing MgMg4Nb2Si2 hexagonal bipyramids. Both Mg(1)-Mg(1) bond lengths are 2.82 Å. There is one shorter (2.46 Å) and one longer (2.55 Å) Mg(1)-Mg(2) bond length. There is one shorter (2.70 Å) and one longer (2.92 Å) Mg(1)-Nb(1) bond length. There is one shorter (2.80 Å) and one longer (3.01 Å) Mg(1)-Si(1) bond length. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Nb(1), and two equivalent Si(1) atoms to form a mixture of distorted edge and corner-sharing MgMg4Nb2Si2 hexagonal bipyramids. Both Mg(2)-Mg(2) bond lengths are 2.82 Å. There is one shorter (2.70 Å) and one longer (2.92 Å) Mg(2)-Nb(1) bond length. There is one shorter (2.69 Å) and one longer (2.91 Å) Mg(2)-Si(1) bond length. Nb(1) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Nb(1), and two equivalent Si(1) atoms. Both Nb(1)-Nb(1) bond lengths are 2.82 Å. There is one shorter (2.43 Å) and one longer (2.63 Å) Nb(1)-Si(1) bond length. Si(1) is bonded in a 6-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Nb(1) atoms.