data_MgNiHg2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.34
_cell_length_b   3.34
_cell_length_c   6.45
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgNiHg2
_chemical_formula_sum   'Mg1 Ni1 Hg2'
_cell_volume   72.09
_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
  Mg  Mg2  1  0.0  0.0  0.0  1.0
  Ni  Ni3  1  0.0  0.0  0.23  1.0
  Hg  Hg0  1  0.67  0.67  0.69  1.0
  Hg  Hg1  1  0.67  0.67  0.76  1.0

data_MgNiHg2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.73
_cell_length_b   4.73
_cell_length_c   6.45
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   MgNiHg2
_chemical_formula_sum   'Mg2 Ni2 Hg4'
_cell_volume   144.19
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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  2  0.0  0.0  0.0  1.0
  Ni  Ni1  2  0.0  0.0  0.23  1.0
  Hg  Hg2  2  0.17  0.5  0.69  1.0
  Hg  Hg3  2  0.17  0.5  0.76  1.0

Mg Ni Hg Hg
Mg Ni Hg Hg 0 1 o o o 2 3 o o o 
MgNiHg2 crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two MgNiHg2 clusters. Mg(1) is bonded in a 2-coordinate geometry to one Ni(1) and one Hg(2) atom. The Mg(1)-Ni(1) bond length is 1.46 Å. The Mg(1)-Hg(2) bond length is 2.20 Å. Ni(1) is bonded in a single-bond geometry to one Mg(1) atom. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a single-bond geometry to one Hg(2) atom. The Hg(1)-Hg(2) bond length is 0.41 Å. In the second Hg site, Hg(2) is bonded in a 2-coordinate geometry to one Mg(1) and one Hg(1) atom.