data_MgHg2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.94
_cell_length_b   6.94
_cell_length_c   6.94
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgHg2
_chemical_formula_sum   'Mg4 Hg8'
_cell_volume   334.22
_cell_formula_units_Z   4
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  Mg8  1  0.0  0.0  0.0  1.0
  Mg  Mg9  1  0.0  0.47  0.47  1.0
  Mg  Mg10  1  0.47  0.0  0.47  1.0
  Mg  Mg11  1  0.47  0.47  0.0  1.0
  Hg  Hg0  1  0.92  0.39  0.02  1.0
  Hg  Hg1  1  0.92  0.02  0.55  1.0
  Hg  Hg2  1  0.55  0.92  0.02  1.0
  Hg  Hg3  1  0.55  0.55  0.55  1.0
  Hg  Hg4  1  0.39  0.39  0.39  1.0
  Hg  Hg5  1  0.39  0.02  0.92  1.0
  Hg  Hg6  1  0.02  0.92  0.39  1.0
  Hg  Hg7  1  0.02  0.55  0.92  1.0

data_MgHg2
_symmetry_space_group_name_H-M   R3
_cell_length_a   9.81
_cell_length_b   9.81
_cell_length_c   12.02
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   MgHg2
_chemical_formula_sum   'Mg12 Hg24'
_cell_volume   1002.66
_cell_formula_units_Z   12
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  'x+1/3, y+2/3, z+2/3'
  5  '-y+1/3, x-y+2/3, z+2/3'
  6  '-x+y+1/3, -x+2/3, z+2/3'
  7  'x+2/3, y+1/3, z+1/3'
  8  '-y+2/3, x-y+1/3, z+1/3'
  9  '-x+y+2/3, -x+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  9  0.02  0.51  0.98  1.0
  Mg  Mg1  3  0.0  0.0  0.0  1.0
  Hg  Hg2  9  0.06  0.47  0.5  1.0
  Hg  Hg3  9  0.14  0.75  0.78  1.0
  Hg  Hg4  3  0.0  0.0  0.39  1.0
  Hg  Hg5  3  0.0  0.0  0.55  1.0

Mg Mg Mg Mg Hg Hg Hg Hg Hg Hg Hg Hg
Mg Mg Mg Mg Hg Hg Hg Hg Hg Hg Hg Hg 0 6 - - o 0 5 - o - 0 4 - o o 0 11 o - - 0 10 o - o 0 9 o o - 1 4 - o o 1 5 - o o 1 7 - o o 1 8 o o o 1 10 o o o 1 11 o o o 2 10 o - o 2 8 o o o 2 9 o o o 2 6 o - o 2 7 o - o 2 5 o o o 3 9 o o - 3 8 o o o 3 11 o o - 3 4 o o o 3 7 o o - 3 6 o o o 4 11 + o - 5 10 + - o 6 9 o + - 7 8 o o o 
MgHg2 is Hausmannite-like structured and crystallizes in the trigonal R3 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent Hg(1) and three equivalent Hg(2) atoms to form MgHg6 octahedra that share corners with twelve equivalent Mg(2)Hg6 octahedra, corners with three equivalent Hg(1)Mg3Hg tetrahedra, and corners with three equivalent Hg(2)Mg3Hg tetrahedra. The corner-sharing octahedral tilt angles range from 67-79°. All Mg(1)-Hg(1) bond lengths are 2.74 Å. All Mg(1)-Hg(2) bond lengths are 3.15 Å. In the second Mg site, Mg(2) is bonded to one Hg(3), one Hg(4), two equivalent Hg(1), and two equivalent Hg(2) atoms to form MgHg6 octahedra that share corners with four equivalent Mg(1)Hg6 octahedra, corners with eight equivalent Mg(2)Hg6 octahedra,  a cornercorner with one Hg(3)Mg3Hg tetrahedra,  a cornercorner with one Hg(4)Mg3Hg tetrahedra, corners with two equivalent Hg(1)Mg3Hg tetrahedra, and corners with two equivalent Hg(2)Mg3Hg tetrahedra. The corner-sharing octahedral tilt angles range from 67-79°. The Mg(2)-Hg(3) bond length is 3.20 Å. The Mg(2)-Hg(4) bond length is 2.80 Å. There is one shorter (3.15 Å) and one longer (3.20 Å) Mg(2)-Hg(1) bond length. There is one shorter (3.15 Å) and one longer (3.20 Å) Mg(2)-Hg(2) bond length. There are four inequivalent Hg sites. In the first Hg site, Hg(1) is bonded to one Mg(1), two equivalent Mg(2), and one Hg(2) atom to form HgMg3Hg tetrahedra that share  a cornercorner with one Mg(1)Hg6 octahedra, corners with two equivalent Mg(2)Hg6 octahedra, corners with two equivalent Hg(3)Mg3Hg tetrahedra, corners with two equivalent Hg(4)Mg3Hg tetrahedra, corners with four equivalent Hg(1)Mg3Hg tetrahedra, and corners with seven equivalent Hg(2)Mg3Hg tetrahedra. The corner-sharing octahedral tilt angles range from 52-76°. The Hg(1)-Hg(2) bond length is 1.58 Å. In the second Hg site, Hg(2) is bonded to one Mg(1), two equivalent Mg(2), and one Hg(1) atom to form HgMg3Hg tetrahedra that share  a cornercorner with one Mg(1)Hg6 octahedra, corners with two equivalent Mg(2)Hg6 octahedra, corners with two equivalent Hg(3)Mg3Hg tetrahedra, corners with two equivalent Hg(4)Mg3Hg tetrahedra, corners with four equivalent Hg(2)Mg3Hg tetrahedra, and corners with seven equivalent Hg(1)Mg3Hg tetrahedra. The corner-sharing octahedral tilt angles range from 54-76°. In the third Hg site, Hg(3) is bonded to three equivalent Mg(2) and one Hg(4) atom to form HgMg3Hg tetrahedra that share corners with three equivalent Mg(2)Hg6 octahedra, corners with three equivalent Hg(4)Mg3Hg tetrahedra, corners with six equivalent Hg(1)Mg3Hg tetrahedra, and corners with six equivalent Hg(2)Mg3Hg tetrahedra. The corner-sharing octahedral tilt angles are 72°. The Hg(3)-Hg(4) bond length is 2.03 Å. In the fourth Hg site, Hg(4) is bonded to three equivalent Mg(2) and one Hg(3) atom to form HgMg3Hg tetrahedra that share corners with three equivalent Mg(2)Hg6 octahedra, corners with three equivalent Hg(3)Mg3Hg tetrahedra, corners with six equivalent Hg(1)Mg3Hg tetrahedra, and corners with six equivalent Hg(2)Mg3Hg tetrahedra. The corner-sharing octahedral tilt angles are 70°.