The compound described by Sr2Mg1 crystallizes in the trigonal R32 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to two equivalent Sr(2), six equivalent Sr(1), and four equivalent Mg(1) atoms to form distorted SrSr8Mg4 cuboctahedra that share corners with eighteen equivalent Sr(1)Sr8Mg4 cuboctahedra, edges with four equivalent Sr(2)Sr6Mg6 cuboctahedra, edges with six equivalent Sr(1)Sr8Mg4 cuboctahedra, faces with four equivalent Sr(2)Sr6Mg6 cuboctahedra, and faces with eight equivalent Sr(1)Sr8Mg4 cuboctahedra. In the second Sr site, Sr(2) is bonded to six equivalent Sr(1) and six equivalent Mg(1) atoms to form SrSr6Mg6 cuboctahedra that share corners with six equivalent Sr(2)Sr6Mg6 cuboctahedra, edges with six equivalent Sr(2)Sr6Mg6 cuboctahedra, edges with twelve equivalent Sr(1)Sr8Mg4 cuboctahedra, and faces with twelve equivalent Sr(1)Sr8Mg4 cuboctahedra. Mg(1) is bonded in a 9-coordinate geometry to three equivalent Sr(2) and six equivalent Sr(1) atoms. is represented by the CIF file [CIF]
data_Sr2Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.505
_cell_length_b   7.505
_cell_length_c   7.505
_cell_angle_alpha   54.540
_cell_angle_beta   54.540
_cell_angle_gamma   54.540
_symmetry_Int_Tables_number   1
_cell_volume   260.886
_cell_formula_units_Z   2
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
  Sr  Sr0  1  0.000  0.672  0.328  1.0
  Sr  Sr1  1  0.328  0.000  0.672  1.0
  Sr  Sr2  1  0.500  0.500  0.500  1.0
  Sr  Sr3  1  0.672  0.328  0.000  1.0
  Mg  Mg4  1  0.166  0.166  0.166  1.0
  Mg  Mg5  1  0.834  0.834  0.834  1.0
[/CIF]
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The compound described by Sr2Mg1 crystallizes in the trigonal R32 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to two equivalent Sr(2), six equivalent Sr(1), and four equivalent Mg(1) atoms to form distorted SrSr8Mg4 cuboctahedra that share corners with eighteen equivalent Sr(1)Sr8Mg4 cuboctahedra, edges with four equivalent Sr(2)Sr6Mg6 cuboctahedra, edges with six equivalent Sr(1)Sr8Mg4 cuboctahedra, faces with four equivalent Sr(2)Sr6Mg6 cuboctahedra, and faces with eight equivalent Sr(1)Sr8Mg4 cuboctahedra. In the second Sr site, Sr(2) is bonded to six equivalent Sr(1) and six equivalent Mg(1) atoms to form SrSr6Mg6 cuboctahedra that share corners with six equivalent Sr(2)Sr6Mg6 cuboctahedra, edges with six equivalent Sr(2)Sr6Mg6 cuboctahedra, edges with twelve equivalent Sr(1)Sr8Mg4 cuboctahedra, and faces with twelve equivalent Sr(1)Sr8Mg4 cuboctahedra. Mg(1) is bonded in a 9-coordinate geometry to three equivalent Sr(2) and six equivalent Sr(1) atoms. is represented by the CIF file [CIF]
data_Sr2Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.505
_cell_length_b   7.505
_cell_length_c   7.505
_cell_angle_alpha   54.540
_cell_angle_beta   54.540
_cell_angle_gamma   54.540
_symmetry_Int_Tables_number   1
_cell_volume   260.886
_cell_formula_units_Z   2
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
  Sr  Sr0  1  0.000  0.672  0.328  1.0
  Sr  Sr1  1  0.328  0.000  0.672  1.0
  Sr  Sr2  1  0.500  0.500  0.500  1.0
  Sr  Sr3  1  0.672  0.328  0.000  1.0
  Mg  Mg4  1  0.166  0.166  0.166  1.0
  Mg  Mg5  1  0.834  0.834  0.834  1.0
[/CIF]
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