data_Mn2AlSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.5
_cell_length_b   4.5
_cell_length_c   3.02
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   103.73
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mn2AlSe
_chemical_formula_sum   'Mn2 Al1 Se1'
_cell_volume   59.49
_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
  Mn  Mn1  1  0.39  0.77  0.51  1.0
  Mn  Mn2  1  0.39  0.23  0.51  1.0
  Al  Al0  1  0.0  0.0  0.0  1.0
  Se  Se3  1  0.78  0.0  0.0  1.0

data_Mn2AlSe
_symmetry_space_group_name_H-M   Pm
_cell_length_a   4.5
_cell_length_b   3.02
_cell_length_c   4.5
_cell_angle_alpha   90.0
_cell_angle_beta   103.73
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   6
_chemical_formula_structural   Mn2AlSe
_chemical_formula_sum   'Mn2 Al1 Se1'
_cell_volume   59.49
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '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
  Mn  Mn0  1  0.39  0.5  0.23  1.0
  Mn  Mn1  1  0.39  0.5  0.77  1.0
  Al  Al2  1  0.0  0.0  0.0  1.0
  Se  Se3  1  0.78  0.0  0.0  1.0

Mn Mn Al Se
Mn Mn Al Se 0 2 o + + 0 1 o + o 0 1 o o o 0 3 o + o 0 3 o + + 1 2 o o o 1 2 o o + 1 3 o o + 2 3 - o o 
Mn2AlSe crystallizes in the triclinic P1 space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 2-coordinate geometry to two equivalent Mn(2) and two equivalent Se(1) atoms. There is one shorter (2.06 Å) and one longer (2.45 Å) Mn(1)-Mn(2) bond length. There is one shorter (2.34 Å) and one longer (2.38 Å) Mn(1)-Se(1) bond length. In the second Mn site, Mn(2) is bonded in a 6-coordinate geometry to two equivalent Mn(1), two equivalent Al(1), and two equivalent Se(1) atoms. There is one shorter (2.34 Å) and one longer (2.38 Å) Mn(2)-Al(1) bond length. There is one shorter (2.69 Å) and one longer (2.72 Å) Mn(2)-Se(1) bond length. Al(1) is bonded in a single-bond geometry to two equivalent Mn(2) and one Se(1) atom. The Al(1)-Se(1) bond length is 0.98 Å. Se(1) is bonded in a distorted single-bond geometry to two equivalent Mn(1), two equivalent Mn(2), and one Al(1) atom.