data_BaBeTl2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.91
_cell_length_b   4.91
_cell_length_c   5.0
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   BaBeTl2
_chemical_formula_sum   'Ba1 Be1 Tl2'
_cell_volume   120.4
_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  Ba0  1  0.45  0.45  0.0  1.0
  Be  Be1  1  0.0  0.0  0.0  1.0
  Tl  Tl2  1  0.0  0.45  0.5  1.0
  Tl  Tl3  1  0.45  0.0  0.5  1.0

data_BaBeTl2
_symmetry_space_group_name_H-M   Amm2
_cell_length_a   5.0
_cell_length_b   6.94
_cell_length_c   6.94
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   38
_chemical_formula_structural   BaBeTl2
_chemical_formula_sum   'Ba2 Be2 Tl4'
_cell_volume   240.81
_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, y, z'
  4  'x, -y, z'
  5  'x, y+1/2, z+1/2'
  6  '-x, -y+1/2, z+1/2'
  7  '-x, y+1/2, z+1/2'
  8  'x, -y+1/2, z+1/2'
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  0.45  1.0
  Be  Be1  2  0.0  0.0  0.0  1.0
  Tl  Tl2  4  0.5  0.23  0.23  1.0

Ba Be Tl Tl
BaBeTl2 crystallizes in the orthorhombic Amm2 space group. Ba(1) is bonded to four equivalent Be(1) and eight equivalent Tl(1) atoms to form a mixture of distorted face and corner-sharing BaBe4Tl8 cuboctahedra. There are a spread of Ba(1)-Be(1) bond distances ranging from 3.15-3.79 Å. There are four shorter (3.35 Å) and four longer (3.67 Å) Ba(1)-Tl(1) bond lengths. Be(1) is bonded in a distorted square co-planar geometry to four equivalent Ba(1) atoms. Tl(1) is bonded in a 7-coordinate geometry to four equivalent Ba(1) and three equivalent Tl(1) atoms. There is one shorter (3.15 Å) and two longer (3.48 Å) Tl(1)-Tl(1) bond lengths.