data_Nb3Hg4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.23
_cell_length_b   13.23
_cell_length_c   13.23
_cell_angle_alpha   165.52
_cell_angle_beta   165.52
_cell_angle_gamma   20.53
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Nb3Hg4
_chemical_formula_sum   'Nb3 Hg4'
_cell_volume   144.67
_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
  Nb  Nb4  1  0.0  0.0  0.0  1.0
  Nb  Nb5  1  0.0  0.0  0.14  1.0
  Nb  Nb6  1  0.0  0.0  0.89  1.0
  Hg  Hg0  1  0.0  0.0  0.94  1.0
  Hg  Hg1  1  0.0  0.0  0.16  1.0
  Hg  Hg2  1  0.0  0.0  0.87  1.0
  Hg  Hg3  1  0.0  0.0  0.09  1.0

data_Nb3Hg4
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.71
_cell_length_b   4.71
_cell_length_c   13.23
_cell_angle_alpha   90.0
_cell_angle_beta   100.27
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Nb3Hg4
_chemical_formula_sum   'Nb6 Hg8'
_cell_volume   289.33
_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
  Nb  Nb0  2  0.0  0.0  0.0  1.0
  Nb  Nb1  2  0.0  0.0  0.11  1.0
  Nb  Nb2  2  0.0  0.0  0.86  1.0
  Hg  Hg3  2  0.0  0.0  0.06  1.0
  Hg  Hg4  2  0.0  0.0  0.13  1.0
  Hg  Hg5  2  0.0  0.0  0.84  1.0
  Hg  Hg6  2  0.0  0.0  0.91  1.0

Nb Nb Nb Hg Hg Hg Hg
Nb3Hg4 crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two Nb3Hg4 clusters. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a linear geometry to one Hg(1) and one Hg(4) atom. The Nb(1)-Hg(1) bond length is 0.79 Å. The Nb(1)-Hg(4) bond length is 1.21 Å. In the second Nb site, Nb(2,3) is bonded in a linear geometry to one Hg(2) and one Hg(4) atom. The Nb(2,3)-Hg(2) bond length is 0.26 Å. The Nb(2,3)-Hg(4) bond length is 0.62 Å. There are four inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a linear geometry to one Nb(1) and one Nb(2,3) atom. The Hg(1)-Nb(2,3) bond length is 0.62 Å. In the second Hg site, Hg(2) is bonded in a single-bond geometry to one Nb(2,3) atom. In the third Hg site, Hg(3) is bonded in a single-bond geometry to one Nb(2,3) atom. The Hg(3)-Nb(2,3) bond length is 0.26 Å. In the fourth Hg site, Hg(4) is bonded in a linear geometry to one Nb(1) and one Nb(2,3) atom.