The material structure described by Mg5Sb crystallizes in the monoclinic Cm space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), three equivalent Mg(5), and two equivalent Sb(1) atoms to form distorted MgMg10Sb2 cuboctahedra that share corners with two equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with two equivalent Sb(1)Mg10 cuboctahedra, corners with six equivalent Mg(1)Mg10Sb2 cuboctahedra, corners with six equivalent Mg(4)Mg11Sb cuboctahedra, corners with six equivalent Mg(2)Mg5Sb3 cuboctahedra,  an edgeedge with one Mg(2)Mg5Sb3 cuboctahedra, edges with two equivalent Mg(5)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(4)Mg11Sb cuboctahedra, edges with three equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with four equivalent Sb(1)Mg10 cuboctahedra, faces with two equivalent Mg(1)Mg10Sb2 cuboctahedra, faces with three equivalent Mg(4)Mg11Sb cuboctahedra, faces with three equivalent Mg(2)Mg5Sb3 cuboctahedra, faces with three equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with three equivalent Sb(1)Mg10 cuboctahedra, and faces with five equivalent Mg(5)Mg10Sb2 cuboctahedra. In the second Mg site, Mg(2) is bonded to one Mg(5), two equivalent Mg(1), two equivalent Mg(4), and three equivalent Sb(1) atoms to form distorted MgMg5Sb3 cuboctahedra that share corners with two equivalent Mg(5)Mg10Sb2 cuboctahedra, corners with two equivalent Sb(1)Mg10 cuboctahedra, corners with four equivalent Mg(2)Mg5Sb3 cuboctahedra, corners with six equivalent Mg(1)Mg10Sb2 cuboctahedra, corners with seven equivalent Mg(4)Mg11Sb cuboctahedra,  an edgeedge with one Mg(1)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(5)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(4)Mg11Sb cuboctahedra, edges with three equivalent Sb(1)Mg10 cuboctahedra, edges with six equivalent Mg(3)Mg6Sb2 cuboctahedra,  a faceface with one Mg(3)Mg6Sb2 cuboctahedra, faces with two equivalent Mg(2)Mg5Sb3 cuboctahedra, faces with three equivalent Mg(1)Mg10Sb2 cuboctahedra, and faces with three equivalent Mg(5)Mg10Sb2 cuboctahedra. In the third Mg site, Mg(3) is bonded to one Mg(1), two equivalent Mg(5), three equivalent Mg(4), and two equivalent Sb(1) atoms to form distorted MgMg6Sb2 cuboctahedra that share corners with two equivalent Mg(1)Mg10Sb2 cuboctahedra, corners with two equivalent Mg(4)Mg11Sb cuboctahedra, corners with four equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with six equivalent Mg(5)Mg10Sb2 cuboctahedra, corners with seven equivalent Sb(1)Mg10 cuboctahedra,  an edgeedge with one Mg(5)Mg10Sb2 cuboctahedra,  an edgeedge with one Sb(1)Mg10 cuboctahedra, edges with three equivalent Mg(1)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(4)Mg11Sb cuboctahedra, edges with six equivalent Mg(2)Mg5Sb3 cuboctahedra,  a faceface with one Mg(2)Mg5Sb3 cuboctahedra, faces with two equivalent Mg(4)Mg11Sb cuboctahedra, faces with two equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with three equivalent Mg(1)Mg10Sb2 cuboctahedra, and faces with three equivalent Mg(5)Mg10Sb2 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(3), and one Sb(1) atom to form distorted MgMg11Sb cuboctahedra that share corners with two equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with six equivalent Mg(1)Mg10Sb2 cuboctahedra, corners with six equivalent Mg(4)Mg11Sb cuboctahedra, corners with seven equivalent Mg(2)Mg5Sb3 cuboctahedra, edges with three equivalent Mg(1)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(2)Mg5Sb3 cuboctahedra, edges with three equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with four equivalent Sb(1)Mg10 cuboctahedra, edges with six equivalent Mg(5)Mg10Sb2 cuboctahedra, faces with two equivalent Mg(4)Mg11Sb cuboctahedra, faces with two equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with three equivalent Mg(1)Mg10Sb2 cuboctahedra, faces with three equivalent Mg(5)Mg10Sb2 cuboctahedra, and faces with four equivalent Sb(1)Mg10 cuboctahedra. In the fifth Mg site, Mg(5) is bonded to one Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(1), and two equivalent Sb(1) atoms to form distorted MgMg10Sb2 cuboctahedra that share corners with two equivalent Mg(2)Mg5Sb3 cuboctahedra, corners with six equivalent Mg(5)Mg10Sb2 cuboctahedra, corners with six equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with eight equivalent Sb(1)Mg10 cuboctahedra,  an edgeedge with one Mg(3)Mg6Sb2 cuboctahedra,  an edgeedge with one Sb(1)Mg10 cuboctahedra, edges with two equivalent Mg(1)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(2)Mg5Sb3 cuboctahedra, edges with six equivalent Mg(4)Mg11Sb cuboctahedra, faces with two equivalent Mg(5)Mg10Sb2 cuboctahedra, faces with three equivalent Mg(4)Mg11Sb cuboctahedra, faces with three equivalent Mg(2)Mg5Sb3 cuboctahedra, faces with three equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with three equivalent Sb(1)Mg10 cuboctahedra, and faces with five equivalent Mg(1)Mg10Sb2 cuboctahedra. Sb(1) is bonded to one Mg(4), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(5), and three equivalent Mg(2) atoms to form distorted SbMg10 cuboctahedra that share corners with two equivalent Mg(1)Mg10Sb2 cuboctahedra, corners with two equivalent Mg(2)Mg5Sb3 cuboctahedra, corners with four equivalent Sb(1)Mg10 cuboctahedra, corners with seven equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with eight equivalent Mg(5)Mg10Sb2 cuboctahedra,  an edgeedge with one Mg(5)Mg10Sb2 cuboctahedra,  an edgeedge with one Mg(3)Mg6Sb2 cuboctahedra, edges with three equivalent Mg(2)Mg5Sb3 cuboctahedra, edges with four equivalent Mg(1)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(4)Mg11Sb cuboctahedra, faces with two equivalent Sb(1)Mg10 cuboctahedra, faces with three equivalent Mg(1)Mg10Sb2 cuboctahedra, faces with three equivalent Mg(5)Mg10Sb2 cuboctahedra, and faces with four equivalent Mg(4)Mg11Sb cuboctahedra. is represented by the CIF card [CIF]
data_Mg5Sb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.086
_cell_length_b   6.086
_cell_length_c   7.676
_cell_angle_alpha   74.078
_cell_angle_beta   74.078
_cell_angle_gamma   31.055
_symmetry_Int_Tables_number   1
_cell_volume   140.610
_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  0.998  0.998  0.997  1.0
  Mg  Mg1  1  0.333  0.333  0.332  1.0
  Mg  Mg2  1  0.944  0.944  0.611  1.0
  Mg  Mg3  1  0.669  0.669  0.668  1.0
  Mg  Mg4  1  0.280  0.280  0.942  1.0
  Sb  Sb5  1  0.609  0.609  0.282  1.0
[/CIF]
.
The material structure described by Mg5Sb crystallizes in the monoclinic Cm space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), three equivalent Mg(5), and two equivalent Sb(1) atoms to form distorted MgMg10Sb2 cuboctahedra that share corners with two equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with two equivalent Sb(1)Mg10 cuboctahedra, corners with six equivalent Mg(1)Mg10Sb2 cuboctahedra, corners with six equivalent Mg(4)Mg11Sb cuboctahedra, corners with six equivalent Mg(2)Mg5Sb3 cuboctahedra,  an edgeedge with one Mg(2)Mg5Sb3 cuboctahedra, edges with two equivalent Mg(5)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(4)Mg11Sb cuboctahedra, edges with three equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with four equivalent Sb(1)Mg10 cuboctahedra, faces with two equivalent Mg(1)Mg10Sb2 cuboctahedra, faces with three equivalent Mg(4)Mg11Sb cuboctahedra, faces with three equivalent Mg(2)Mg5Sb3 cuboctahedra, faces with three equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with three equivalent Sb(1)Mg10 cuboctahedra, and faces with five equivalent Mg(5)Mg10Sb2 cuboctahedra. In the second Mg site, Mg(2) is bonded to one Mg(5), two equivalent Mg(1), two equivalent Mg(4), and three equivalent Sb(1) atoms to form distorted MgMg5Sb3 cuboctahedra that share corners with two equivalent Mg(5)Mg10Sb2 cuboctahedra, corners with two equivalent Sb(1)Mg10 cuboctahedra, corners with four equivalent Mg(2)Mg5Sb3 cuboctahedra, corners with six equivalent Mg(1)Mg10Sb2 cuboctahedra, corners with seven equivalent Mg(4)Mg11Sb cuboctahedra,  an edgeedge with one Mg(1)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(5)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(4)Mg11Sb cuboctahedra, edges with three equivalent Sb(1)Mg10 cuboctahedra, edges with six equivalent Mg(3)Mg6Sb2 cuboctahedra,  a faceface with one Mg(3)Mg6Sb2 cuboctahedra, faces with two equivalent Mg(2)Mg5Sb3 cuboctahedra, faces with three equivalent Mg(1)Mg10Sb2 cuboctahedra, and faces with three equivalent Mg(5)Mg10Sb2 cuboctahedra. In the third Mg site, Mg(3) is bonded to one Mg(1), two equivalent Mg(5), three equivalent Mg(4), and two equivalent Sb(1) atoms to form distorted MgMg6Sb2 cuboctahedra that share corners with two equivalent Mg(1)Mg10Sb2 cuboctahedra, corners with two equivalent Mg(4)Mg11Sb cuboctahedra, corners with four equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with six equivalent Mg(5)Mg10Sb2 cuboctahedra, corners with seven equivalent Sb(1)Mg10 cuboctahedra,  an edgeedge with one Mg(5)Mg10Sb2 cuboctahedra,  an edgeedge with one Sb(1)Mg10 cuboctahedra, edges with three equivalent Mg(1)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(4)Mg11Sb cuboctahedra, edges with six equivalent Mg(2)Mg5Sb3 cuboctahedra,  a faceface with one Mg(2)Mg5Sb3 cuboctahedra, faces with two equivalent Mg(4)Mg11Sb cuboctahedra, faces with two equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with three equivalent Mg(1)Mg10Sb2 cuboctahedra, and faces with three equivalent Mg(5)Mg10Sb2 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(3), and one Sb(1) atom to form distorted MgMg11Sb cuboctahedra that share corners with two equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with six equivalent Mg(1)Mg10Sb2 cuboctahedra, corners with six equivalent Mg(4)Mg11Sb cuboctahedra, corners with seven equivalent Mg(2)Mg5Sb3 cuboctahedra, edges with three equivalent Mg(1)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(2)Mg5Sb3 cuboctahedra, edges with three equivalent Mg(3)Mg6Sb2 cuboctahedra, edges with four equivalent Sb(1)Mg10 cuboctahedra, edges with six equivalent Mg(5)Mg10Sb2 cuboctahedra, faces with two equivalent Mg(4)Mg11Sb cuboctahedra, faces with two equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with three equivalent Mg(1)Mg10Sb2 cuboctahedra, faces with three equivalent Mg(5)Mg10Sb2 cuboctahedra, and faces with four equivalent Sb(1)Mg10 cuboctahedra. In the fifth Mg site, Mg(5) is bonded to one Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(1), and two equivalent Sb(1) atoms to form distorted MgMg10Sb2 cuboctahedra that share corners with two equivalent Mg(2)Mg5Sb3 cuboctahedra, corners with six equivalent Mg(5)Mg10Sb2 cuboctahedra, corners with six equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with eight equivalent Sb(1)Mg10 cuboctahedra,  an edgeedge with one Mg(3)Mg6Sb2 cuboctahedra,  an edgeedge with one Sb(1)Mg10 cuboctahedra, edges with two equivalent Mg(1)Mg10Sb2 cuboctahedra, edges with three equivalent Mg(2)Mg5Sb3 cuboctahedra, edges with six equivalent Mg(4)Mg11Sb cuboctahedra, faces with two equivalent Mg(5)Mg10Sb2 cuboctahedra, faces with three equivalent Mg(4)Mg11Sb cuboctahedra, faces with three equivalent Mg(2)Mg5Sb3 cuboctahedra, faces with three equivalent Mg(3)Mg6Sb2 cuboctahedra, faces with three equivalent Sb(1)Mg10 cuboctahedra, and faces with five equivalent Mg(1)Mg10Sb2 cuboctahedra. Sb(1) is bonded to one Mg(4), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(5), and three equivalent Mg(2) atoms to form distorted SbMg10 cuboctahedra that share corners with two equivalent Mg(1)Mg10Sb2 cuboctahedra, corners with two equivalent Mg(2)Mg5Sb3 cuboctahedra, corners with four equivalent Sb(1)Mg10 cuboctahedra, corners with seven equivalent Mg(3)Mg6Sb2 cuboctahedra, corners with eight equivalent Mg(5)Mg10Sb2 cuboctahedra,  an edgeedge with one Mg(5)Mg10Sb2 cuboctahedra,  an edgeedge with one Mg(3)Mg6Sb2 cuboctahedra, edges with three equivalent Mg(2)Mg5Sb3 cuboctahedra, edges with four equivalent Mg(1)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(4)Mg11Sb cuboctahedra, faces with two equivalent Sb(1)Mg10 cuboctahedra, faces with three equivalent Mg(1)Mg10Sb2 cuboctahedra, faces with three equivalent Mg(5)Mg10Sb2 cuboctahedra, and faces with four equivalent Mg(4)Mg11Sb cuboctahedra. is represented by the CIF card [CIF]
data_Mg5Sb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.086
_cell_length_b   6.086
_cell_length_c   7.676
_cell_angle_alpha   74.078
_cell_angle_beta   74.078
_cell_angle_gamma   31.055
_symmetry_Int_Tables_number   1
_cell_volume   140.610
_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  0.998  0.998  0.997  1.0
  Mg  Mg1  1  0.333  0.333  0.332  1.0
  Mg  Mg2  1  0.944  0.944  0.611  1.0
  Mg  Mg3  1  0.669  0.669  0.668  1.0
  Mg  Mg4  1  0.280  0.280  0.942  1.0
  Sb  Sb5  1  0.609  0.609  0.282  1.0
[/CIF]
.