data_Mg2Sb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.38
_cell_length_b   5.38
_cell_length_c   5.38
_cell_angle_alpha   136.68
_cell_angle_beta   136.68
_cell_angle_gamma   62.93
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2Sb
_chemical_formula_sum   'Mg2 Sb1'
_cell_volume   72.22
_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  0.06  1.0
  Mg  Mg1  1  0.0  0.0  0.11  1.0
  Sb  Sb2  1  0.0  0.0  0.0  1.0

data_Mg2Sb
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.61
_cell_length_b   5.61
_cell_length_c   5.38
_cell_angle_alpha   90.0
_cell_angle_beta   121.46
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Mg2Sb
_chemical_formula_sum   'Mg4 Sb2'
_cell_volume   144.44
_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  0.0  0.0  0.06  1.0
  Mg  Mg1  2  0.0  0.0  0.11  1.0
  Sb  Sb2  2  0.0  0.0  0.0  1.0

Mg Mg Sb
Mg2Sb is Indium-like structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two Mg2Sb clusters. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted linear geometry to one Mg(2) and one Sb(1) atom. The Mg(1)-Mg(2) bond length is 0.30 Å. The Mg(1)-Sb(1) bond length is 0.31 Å. In the second Mg site, Mg(2) is bonded in a single-bond geometry to one Mg(1) atom. Sb(1) is bonded in a single-bond geometry to one Mg(1) atom.