data_YSi2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.18
_cell_length_b   8.18
_cell_length_c   8.18
_cell_angle_alpha   24.66
_cell_angle_beta   24.66
_cell_angle_gamma   24.66
_symmetry_Int_Tables_number   1
_chemical_formula_structural   YSi2Se
_chemical_formula_sum   'Y1 Si2 Se1'
_cell_volume   83.77
_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
  Y  Y3  1  0.0  0.0  0.89  1.0
  Si  Si1  1  0.0  0.0  0.57  1.0
  Si  Si2  1  0.0  0.0  0.21  1.0
  Se  Se0  1  0.0  0.0  0.0  1.0

data_YSi2Se
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.05
_cell_length_b   3.49
_cell_length_c   8.18
_cell_angle_alpha   90.0
_cell_angle_beta   104.28
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   YSi2Se
_chemical_formula_sum   'Y2 Si4 Se2'
_cell_volume   167.54
_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
  Y  Y0  2  0.0  0.0  0.11  1.0
  Si  Si1  2  0.0  0.0  0.43  1.0
  Si  Si2  2  0.0  0.0  0.79  1.0
  Se  Se3  2  0.0  0.0  0.0  1.0

Y Si Si Se
Y Si Si Se 0 3 o o + 0 1 o o o 1 1 o + - 1 1 + - o 1 1 + o - 1 2 o o o 1 3 o o + 2 3 o o o 
YSi2Se crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two YSi2Se clusters. Y(1) is bonded in a single-bond geometry to one Si(1) and one Se(1) atom. The Y(1)-Si(1) bond length is 2.63 Å. The Y(1)-Se(1) bond length is 0.90 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a single-bond geometry to one Y(1) atom. In the second Si site, Si(2) is bonded in a single-bond geometry to one Se(1) atom. The Si(2)-Se(1) bond length is 1.73 Å. Se(1) is bonded in a distorted linear geometry to one Y(1) and one Si(2) atom.