data_MgOs2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.21
_cell_length_b   5.21
_cell_length_c   5.21
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgOs2
_chemical_formula_sum   'Mg2 Os4'
_cell_volume   99.9
_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
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Mg  Mg1  1  0.84  0.84  0.84  1.0
  Os  Os2  1  0.76  0.76  0.6  1.0
  Os  Os3  1  0.6  0.76  0.76  1.0
  Os  Os4  1  0.76  0.6  0.76  1.0
  Os  Os5  1  0.6  0.6  0.6  1.0

data_MgOs2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.21
_cell_length_b   5.21
_cell_length_c   12.76
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   MgOs2
_chemical_formula_sum   'Mg6 Os12'
_cell_volume   299.71
_cell_formula_units_Z   6
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
  Mg  Mg0  3  0.0  0.0  0.0  1.0
  Mg  Mg1  3  0.0  0.0  0.16  1.0
  Os  Os2  9  0.11  0.05  0.29  1.0
  Os  Os3  3  0.0  0.0  0.4  1.0

Mg Mg Os Os Os Os
MgOs2 crystallizes in the trigonal R3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted tetrahedral geometry to one Mg(2) and three equivalent Os(1) atoms. The Mg(1)-Mg(2) bond length is 2.02 Å. All Mg(1)-Os(1) bond lengths are 2.59 Å. In the second Mg site, Mg(2) is bonded in a 7-coordinate geometry to one Mg(1), three equivalent Os(1), and three equivalent Os(2) atoms. All Mg(2)-Os(1) bond lengths are 1.75 Å. All Mg(2)-Os(2) bond lengths are 3.24 Å. There are two inequivalent Os sites. In the first Os site, Os(1) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Os(2), and two equivalent Os(1) atoms. The Os(1)-Os(2) bond length is 1.43 Å. Both Os(1)-Os(1) bond lengths are 0.83 Å. In the second Os site, Os(2) is bonded in a 6-coordinate geometry to three equivalent Mg(2) and three equivalent Os(1) atoms.