data_BaAl2Hg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.74
_cell_length_b   4.74
_cell_length_c   4.95
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   BaAl2Hg
_chemical_formula_sum   'Ba1 Al2 Hg1'
_cell_volume   111.35
_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
  Ba  Ba2  1  0.0  0.0  0.0  1.0
  Al  Al0  1  0.37  0.0  0.47  1.0
  Al  Al1  1  0.0  0.37  0.47  1.0
  Hg  Hg3  1  0.37  0.37  0.0  1.0

data_BaAl2Hg
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.71
_cell_length_b   6.71
_cell_length_c   4.95
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   BaAl2Hg
_chemical_formula_sum   'Ba2 Al4 Hg2'
_cell_volume   222.71
_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
  Ba  Ba0  2  0.0  0.0  0.0  1.0
  Al  Al1  4  0.19  0.19  0.47  1.0
  Hg  Hg2  2  0.37  0.0  -0.0  1.0

Ba Al Al Hg
BaHgAl2 crystallizes in the monoclinic Cm space group. Ba(1) is bonded in a 1-coordinate geometry to one Hg(1) and eight equivalent Al(1) atoms. The Ba(1)-Hg(1) bond length is 2.49 Å. There are a spread of Ba(1)-Al(1) bond distances ranging from 2.94-3.96 Å. Hg(1) is bonded in a distorted single-bond geometry to one Ba(1) and four equivalent Al(1) atoms. There are two shorter (2.94 Å) and two longer (3.14 Å) Hg(1)-Al(1) bond lengths. Al(1) is bonded in a 7-coordinate geometry to four equivalent Ba(1), two equivalent Hg(1), and one Al(1) atom. The Al(1)-Al(1) bond length is 2.49 Å.