data_NbCrHg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.8
_cell_length_b   6.8
_cell_length_c   6.8
_cell_angle_alpha   156.21
_cell_angle_beta   156.21
_cell_angle_gamma   33.89
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NbCrHg
_chemical_formula_sum   'Nb1 Cr1 Hg1'
_cell_volume   51.11
_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  0.55  1.0
  Cr  Cr0  1  0.0  0.0  0.02  1.0
  Hg  Hg1  1  0.0  0.0  0.44  1.0

data_NbCrHg
_symmetry_space_group_name_H-M   Cm
_cell_length_a   3.96
_cell_length_b   3.96
_cell_length_c   6.8
_cell_angle_alpha   90.0
_cell_angle_beta   106.95
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   NbCrHg
_chemical_formula_sum   'Nb2 Cr2 Hg2'
_cell_volume   102.22
_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  0.05  0.5  0.55  1.0
  Cr  Cr1  2  0.02  0.0  0.02  1.0
  Hg  Hg2  2  0.44  0.0  0.44  1.0

Nb Cr Hg
NbCrHg crystallizes in the monoclinic Cm space group. Nb(1) is bonded in a single-bond geometry to one Cr(1) and one Hg(1) atom. The Nb(1)-Cr(1) bond length is 3.18 Å. The Nb(1)-Hg(1) bond length is 0.76 Å. Cr(1) is bonded to one Nb(1), four equivalent Cr(1), and one Hg(1) atom to form a mixture of distorted corner and edge-sharing CrNbCr4Hg octahedra. The corner-sharing octahedra are not tilted. All Cr(1)-Cr(1) bond lengths are 2.80 Å. The Cr(1)-Hg(1) bond length is 2.86 Å. Hg(1) is bonded in a single-bond geometry to one Nb(1) and one Cr(1) atom.