data_Mg2NbNi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.87
_cell_length_b   2.87
_cell_length_c   8.08
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2NbNi
_chemical_formula_sum   'Mg2 Nb1 Ni1'
_cell_volume   66.5
_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  0.43  0.43  0.71  1.0
  Mg  Mg1  1  0.43  0.43  0.38  1.0
  Nb  Nb2  1  0.0  0.0  0.04  1.0
  Ni  Ni3  1  0.0  0.0  0.0  1.0

data_Mg2NbNi
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.06
_cell_length_b   4.06
_cell_length_c   8.08
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Mg2NbNi
_chemical_formula_sum   'Mg4 Nb2 Ni2'
_cell_volume   133.0
_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
  Mg  Mg0  2  0.43  0.0  0.38  1.0
  Mg  Mg1  2  0.43  0.0  0.71  1.0
  Nb  Nb2  2  0.0  0.0  0.04  1.0
  Ni  Ni3  2  0.0  0.0  0.0  1.0

Mg Mg Nb Ni
Mg2NbNi crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 9-coordinate geometry to one Mg(2), four equivalent Mg(1), and four equivalent Ni(1) atoms. The Mg(1)-Mg(2) bond length is 2.64 Å. All Mg(1)-Mg(1) bond lengths are 2.87 Å. There are a spread of Mg(1)-Ni(1) bond distances ranging from 2.96-3.31 Å. In the second Mg site, Mg(2) is bonded in a 9-coordinate geometry to one Mg(1), four equivalent Mg(2), and four equivalent Nb(1) atoms. All Mg(2)-Mg(2) bond lengths are 2.87 Å. There are a spread of Mg(2)-Nb(1) bond distances ranging from 3.24-3.56 Å. Nb(1) is bonded in a single-bond geometry to four equivalent Mg(2) and one Ni(1) atom. The Nb(1)-Ni(1) bond length is 0.34 Å. Ni(1) is bonded in a single-bond geometry to four equivalent Mg(1) and one Nb(1) atom.