data_CaTi2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.37
_cell_length_b   3.37
_cell_length_c   7.44
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CaTi2Se
_chemical_formula_sum   'Ca1 Ti2 Se1'
_cell_volume   84.35
_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  0.0  0.86  1.0
  Ti  Ti2  1  0.0  0.0  0.31  1.0
  Ti  Ti3  1  0.68  0.68  0.37  1.0
  Se  Se1  1  0.68  0.68  0.05  1.0

data_CaTi2Se
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.76
_cell_length_b   4.76
_cell_length_c   7.44
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   CaTi2Se
_chemical_formula_sum   'Ca2 Ti4 Se2'
_cell_volume   168.71
_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  2  0.0  0.0  0.86  1.0
  Ti  Ti1  2  0.0  0.0  0.31  1.0
  Ti  Ti2  2  0.18  0.5  0.37  1.0
  Se  Se3  2  0.18  0.5  0.05  1.0

Ca Ti Ti Se
Ca Ti Ti Se 0 3 - - + 1 2 - - o 1 3 - - o 2 3 o o o 
CaTi2Se crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two CaTi2Se clusters. Ca(1) is bonded in a distorted single-bond geometry to one Se(1) atom. The Ca(1)-Se(1) bond length is 2.04 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 2-coordinate geometry to one Ti(2) and one Se(1) atom. The Ti(1)-Ti(2) bond length is 1.58 Å. The Ti(1)-Se(1) bond length is 2.45 Å. In the second Ti site, Ti(2) is bonded in a 2-coordinate geometry to one Ti(1) and one Se(1) atom. The Ti(2)-Se(1) bond length is 2.43 Å. Se(1) is bonded in a distorted single-bond geometry to one Ca(1), one Ti(1), and one Ti(2) atom.