data_Ca2YSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.63
_cell_length_b   6.63
_cell_length_c   6.63
_cell_angle_alpha   140.34
_cell_angle_beta   140.34
_cell_angle_gamma   57.33
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca2YSe
_chemical_formula_sum   'Ca2 Y1 Se1'
_cell_volume   117.55
_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
  Ca  Ca0  1  0.0  0.25  0.91  1.0
  Ca  Ca1  1  0.25  0.0  0.91  1.0
  Y  Y3  1  0.0  0.0  0.81  1.0
  Se  Se2  1  0.0  0.0  0.0  1.0

data_Ca2YSe
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.36
_cell_length_b   6.36
_cell_length_c   6.63
_cell_angle_alpha   90.0
_cell_angle_beta   118.67
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Ca2YSe
_chemical_formula_sum   'Ca4 Y2 Se2'
_cell_volume   235.1
_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
  Ca  Ca0  4  0.12  0.12  0.34  1.0
  Y  Y1  2  0.0  0.0  0.19  1.0
  Se  Se2  2  0.0  0.0  0.0  1.0

Ca Ca Y Se
Ca2YSe is Indium-like structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two Ca2YSe clusters. Ca(1) is bonded in a single-bond geometry to one Y(1) atom. The Ca(1)-Y(1) bond length is 1.24 Å. Y(1) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one Se(1) atom. The Y(1)-Se(1) bond length is 1.23 Å. Se(1) is bonded in a single-bond geometry to one Y(1) atom.