data_NbHg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.42
_cell_length_b   5.42
_cell_length_c   5.42
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NbHg
_chemical_formula_sum   'Nb4 Hg4'
_cell_volume   159.44
_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
  Nb  Nb4  1  0.52  0.52  0.52  1.0
  Nb  Nb5  1  0.19  0.9  0.23  1.0
  Nb  Nb6  1  0.9  0.23  0.19  1.0
  Nb  Nb7  1  0.23  0.19  0.9  1.0
  Hg  Hg0  1  0.19  0.19  0.19  1.0
  Hg  Hg1  1  0.52  0.23  0.9  1.0
  Hg  Hg2  1  0.23  0.9  0.52  1.0
  Hg  Hg3  1  0.9  0.52  0.23  1.0

data_NbHg
_symmetry_space_group_name_H-M   R3
_cell_length_a   7.67
_cell_length_b   7.67
_cell_length_c   9.39
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   NbHg
_chemical_formula_sum   'Nb12 Hg12'
_cell_volume   478.32
_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
  Nb  Nb0  9  0.08  0.88  0.11  1.0
  Nb  Nb1  3  0.0  0.0  0.52  1.0
  Hg  Hg2  9  0.01  0.7  0.22  1.0
  Hg  Hg3  3  0.0  0.0  0.19  1.0

Nb Nb Nb Nb Hg Hg Hg Hg
NbHg crystallizes in the trigonal R3 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted trigonal pyramidal geometry to one Hg(1) and three equivalent Hg(2) atoms. The Nb(1)-Hg(1) bond length is 3.06 Å. All Nb(1)-Hg(2) bond lengths are 2.62 Å. In the second Nb site, Nb(2) is bonded in a distorted water-like geometry to one Hg(1) and one Hg(2) atom. The Nb(2)-Hg(1) bond length is 1.58 Å. The Nb(2)-Hg(2) bond length is 1.58 Å. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a 3-coordinate geometry to one Nb(1) and three equivalent Nb(2) atoms. In the second Hg site, Hg(2) is bonded in a distorted single-bond geometry to one Nb(1) and one Nb(2) atom.