data_La2AlSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.3
_cell_length_b   8.3
_cell_length_c   8.3
_cell_angle_alpha   29.43
_cell_angle_beta   29.43
_cell_angle_gamma   29.43
_symmetry_Int_Tables_number   1
_chemical_formula_structural   La2AlSe
_chemical_formula_sum   'La2 Al1 Se1'
_cell_volume   122.1
_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
  La  La1  1  0.0  0.0  0.96  1.0
  La  La2  1  0.0  0.0  0.84  1.0
  Al  Al0  1  0.0  0.0  0.0  1.0
  Se  Se3  1  0.0  0.0  0.9  1.0

data_La2AlSe
_symmetry_space_group_name_H-M   Cm
_cell_length_a   7.3
_cell_length_b   4.22
_cell_length_c   8.3
_cell_angle_alpha   90.0
_cell_angle_beta   107.06
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   La2AlSe
_chemical_formula_sum   'La4 Al2 Se2'
_cell_volume   244.19
_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
  La  La0  2  0.0  0.0  0.04  1.0
  La  La1  2  0.0  0.0  0.16  1.0
  Al  Al2  2  0.0  0.0  0.0  1.0
  Se  Se3  2  0.0  0.0  0.1  1.0

La La Al Se
La La Al Se 0 2 o o + 0 3 o o o 1 3 o o o 
La2AlSe is Cyanogen Chloride-like structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two La2AlSe clusters. There are two inequivalent La sites. In the first La site, La(1) is bonded in a linear geometry to one Al(1) and one Se(1) atom. The La(1)-Al(1) bond length is 0.34 Å. The La(1)-Se(1) bond length is 0.50 Å. In the second La site, La(2) is bonded in a single-bond geometry to one Se(1) atom. The La(2)-Se(1) bond length is 0.50 Å. Al(1) is bonded in a single-bond geometry to one La(1) atom. Se(1) is bonded in a linear geometry to one La(1) and one La(2) atom.