data_EuMg3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.87
_cell_length_b   4.87
_cell_length_c   4.87
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   EuMg3
_chemical_formula_sum   'Eu1 Mg3'
_cell_volume   115.54
_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
  Eu  Eu0  1  0.0  0.0  0.0  1.0
  Mg  Mg1  1  0.44  0.44  0.0  1.0
  Mg  Mg2  1  0.44  0.0  0.44  1.0
  Mg  Mg3  1  0.0  0.44  0.44  1.0

data_EuMg3
_symmetry_space_group_name_H-M   R3m
_cell_length_a   6.89
_cell_length_b   6.89
_cell_length_c   8.44
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   EuMg3
_chemical_formula_sum   'Eu3 Mg9'
_cell_volume   346.62
_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
  Eu  Eu0  3  0.0  0.0  0.0  1.0
  Mg  Mg1  9  0.04  0.52  0.96  1.0

Eu Mg Mg Mg
Eu Mg Mg Mg 0 2 - o o 0 2 o o - 0 2 o o o 0 1 - o o 0 1 o - o 0 1 o o o 0 3 o - o 0 3 o o - 0 3 o o o 1 3 o o - 1 3 o o o 1 3 + o o 1 2 o o - 1 2 o o o 1 2 o + o 2 3 o - o 2 3 o o o 2 3 + o o 
Mg3Eu is Uranium Silicide structured and crystallizes in the trigonal R3m space group. Mg(1) is bonded in a 10-coordinate geometry to six equivalent Mg(1) and four equivalent Eu(1) atoms. There are two shorter (3.00 Å) and four longer (3.47 Å) Mg(1)-Mg(1) bond lengths. There are a spread of Mg(1)-Eu(1) bond distances ranging from 3.00-3.89 Å. Eu(1) is bonded to twelve equivalent Mg(1) atoms to form a mixture of distorted corner and face-sharing EuMg12 cuboctahedra.