data_NbHg2Pb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.2
_cell_length_b   5.2
_cell_length_c   5.2
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NbHg2Pb
_chemical_formula_sum   'Nb1 Hg2 Pb1'
_cell_volume   99.36
_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  Nb2  1  0.0  0.0  0.0  1.0
  Hg  Hg0  1  0.51  0.51  0.51  1.0
  Hg  Hg1  1  0.84  0.84  0.84  1.0
  Pb  Pb3  1  0.68  0.68  0.68  1.0

data_NbHg2Pb
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.2
_cell_length_b   5.2
_cell_length_c   12.73
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   NbHg2Pb
_chemical_formula_sum   'Nb3 Hg6 Pb3'
_cell_volume   298.09
_cell_formula_units_Z   3
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
  Nb  Nb0  3  0.0  0.0  0.0  1.0
  Hg  Hg1  3  0.0  0.0  0.16  1.0
  Hg  Hg2  3  0.0  0.0  0.49  1.0
  Pb  Pb3  3  0.0  0.0  0.32  1.0

Nb Hg Hg Pb
Nb Hg Hg Pb 0 2 - - - 1 3 o o o 2 3 o o o 
NbHg2Pb crystallizes in the trigonal R3m space group. Nb(1) is bonded to one Hg(2) and three equivalent Pb(1) atoms to form distorted NbHgPb3 trigonal pyramids that share  a cornercorner with one Pb(1)Nb3Hg2 trigonal bipyramid and corners with six equivalent Nb(1)HgPb3 trigonal pyramids. The Nb(1)-Hg(2) bond length is 2.06 Å. All Nb(1)-Pb(1) bond lengths are 3.00 Å. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a single-bond geometry to one Pb(1) atom. The Hg(1)-Pb(1) bond length is 2.06 Å. In the second Hg site, Hg(2) is bonded in a linear geometry to one Nb(1) and one Pb(1) atom. The Hg(2)-Pb(1) bond length is 2.06 Å. Pb(1) is bonded to three equivalent Nb(1), one Hg(1), and one Hg(2) atom to form distorted PbNb3Hg2 trigonal bipyramids that share corners with six equivalent Pb(1)Nb3Hg2 trigonal bipyramids and  a cornercorner with one Nb(1)HgPb3 trigonal pyramid.