data_PuMg3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.18
_cell_length_b   5.18
_cell_length_c   5.18
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   PuMg3
_chemical_formula_sum   'Pu1 Mg3'
_cell_volume   98.52
_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
  Pu  Pu3  1  0.67  0.67  0.67  1.0
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Mg  Mg1  1  0.5  0.5  0.5  1.0
  Mg  Mg2  1  0.83  0.83  0.83  1.0

data_PuMg3
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.18
_cell_length_b   5.18
_cell_length_c   12.7
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   PuMg3
_chemical_formula_sum   'Pu3 Mg9'
_cell_volume   295.56
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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
  Pu  Pu0  3  0.0  0.0  0.33  1.0
  Mg  Mg1  3  0.0  0.0  0.0  1.0
  Mg  Mg2  3  0.0  0.0  0.17  1.0
  Mg  Mg3  3  0.0  0.0  0.5  1.0

Pu Mg Mg Mg
Pu Mg Mg Mg 0 2 o o o 0 3 o o o 1 3 - - - 
Mg3Pu crystallizes in the trigonal R3m space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Mg(3) and three equivalent Pu(1) atoms to form corner-sharing MgPu3Mg trigonal pyramids. The Mg(1)-Mg(3) bond length is 2.12 Å. All Mg(1)-Pu(1) bond lengths are 2.99 Å. In the second Mg site, Mg(2) is bonded in a distorted single-bond geometry to three equivalent Mg(3) and one Pu(1) atom. All Mg(2)-Mg(3) bond lengths are 2.99 Å. The Mg(2)-Pu(1) bond length is 2.12 Å. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Mg(1), three equivalent Mg(2), and one Pu(1) atom. The Mg(3)-Pu(1) bond length is 2.12 Å. Pu(1) is bonded in a distorted linear geometry to one Mg(2), one Mg(3), and three equivalent Mg(1) atoms.