data_Ca2YSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.09
_cell_length_b   4.09
_cell_length_c   6.73
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca2YSi
_chemical_formula_sum   'Ca2 Y1 Si1'
_cell_volume   112.68
_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  0.05  0.05  0.26  1.0
  Ca  Ca1  1  0.05  0.05  0.47  1.0
  Y  Y3  1  0.0  0.0  0.37  1.0
  Si  Si2  1  0.0  0.0  0.0  1.0

data_Ca2YSi
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.79
_cell_length_b   5.79
_cell_length_c   6.73
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Ca2YSi
_chemical_formula_sum   'Ca4 Y2 Si2'
_cell_volume   225.35
_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  0.05  0.0  0.26  1.0
  Ca  Ca1  2  0.05  0.0  0.47  1.0
  Y  Y2  2  0.0  0.0  0.37  1.0
  Si  Si3  2  0.0  0.0  0.0  1.0

Ca Ca Y Si
Ca Ca Y Si 0 2 o o o 0 3 o o o 1 2 o o o 
Ca2YSi crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two Ca2YSi clusters. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a bent 150 degrees geometry to one Y(1) and one Si(1) atom. The Ca(1)-Y(1) bond length is 0.78 Å. The Ca(1)-Si(1) bond length is 1.75 Å. In the second Ca site, Ca(2) is bonded in a single-bond geometry to one Y(1) atom. The Ca(2)-Y(1) bond length is 0.78 Å. Y(1) is bonded in a bent 150 degrees geometry to one Ca(1) and one Ca(2) atom. Si(1) is bonded in a single-bond geometry to one Ca(1) atom.