data_Mg5Nb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.98
_cell_length_b   5.98
_cell_length_c   7.63
_cell_angle_alpha   103.91
_cell_angle_beta   103.91
_cell_angle_gamma   28.4
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg5Nb
_chemical_formula_sum   'Mg5 Nb1'
_cell_volume   125.97
_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  1.0  0.0  0.08  1.0
  Mg  Mg1  1  0.6  0.0  0.05  1.0
  Mg  Mg2  1  0.2  0.0  0.42  1.0
  Mg  Mg3  1  0.72  0.0  0.34  1.0
  Mg  Mg4  1  0.16  0.0  0.79  1.0
  Nb  Nb5  1  0.09  0.0  0.34  1.0

data_Mg5Nb
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.94
_cell_length_b   5.98
_cell_length_c   7.63
_cell_angle_alpha   103.91
_cell_angle_beta   90.0
_cell_angle_gamma   104.2
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg5Nb
_chemical_formula_sum   'Mg5 Nb1'
_cell_volume   125.97
_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  0.0  0.0  0.92  1.0
  Mg  Mg1  1  0.0  0.28  0.66  1.0
  Mg  Mg2  1  0.0  0.4  0.95  1.0
  Mg  Mg3  1  0.0  0.8  0.58  1.0
  Mg  Mg4  1  0.0  0.84  0.21  1.0
  Nb  Nb5  1  0.0  0.91  0.66  1.0

Mg Mg Mg Mg Mg Nb
Mg Mg Mg Mg Mg Nb 0 1 o o o 0 5 + o o 0 4 + o - 1 3 o o o 1 4 o o - 2 5 o o o 2 4 o o o 3 5 + o o 4 5 o o o 4 4 + - o 
Mg5Nb crystallizes in the triclinic P1 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted single-bond geometry to one Mg(2), one Mg(5), and one Nb(1) atom. The Mg(1)-Mg(2) bond length is 2.32 Å. The Mg(1)-Mg(5) bond length is 2.64 Å. The Mg(1)-Nb(1) bond length is 1.95 Å. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(4), one Mg(5), and two equivalent Mg(2) atoms. The Mg(2)-Mg(4) bond length is 2.10 Å. The Mg(2)-Mg(5) bond length is 2.91 Å. Both Mg(2)-Mg(2) bond lengths are 2.94 Å. In the third Mg site, Mg(3) is bonded in a single-bond geometry to one Mg(5) and one Nb(1) atom. The Mg(3)-Mg(5) bond length is 2.90 Å. The Mg(3)-Nb(1) bond length is 0.76 Å. In the fourth Mg site, Mg(4) is bonded in a 2-coordinate geometry to one Mg(2) and one Nb(1) atom. The Mg(4)-Nb(1) bond length is 2.18 Å. In the fifth Mg site, Mg(5) is bonded to one Mg(1), one Mg(2), one Mg(3), and two equivalent Mg(5) atoms to form distorted corner-sharing MgMg5 square pyramids. Both Mg(5)-Mg(5) bond lengths are 2.94 Å. Nb(1) is bonded in a distorted single-bond geometry to one Mg(1), one Mg(3), and one Mg(4) atom.