data_C2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.43
_cell_length_b   2.43
_cell_length_c   5.62
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   C2Se
_chemical_formula_sum   'C2 Se1'
_cell_volume   33.17
_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
  C  C0  1  0.0  0.21  0.81  1.0
  C  C1  1  0.21  0.0  0.81  1.0
  Se  Se2  1  0.0  0.0  0.0  1.0

data_C2Se
_symmetry_space_group_name_H-M   Cm
_cell_length_a   3.44
_cell_length_b   3.44
_cell_length_c   5.62
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   C2Se
_chemical_formula_sum   'C4 Se2'
_cell_volume   66.34
_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
  C  C0  4  0.11  0.11  0.81  1.0
  Se  Se1  2  0.0  0.0  0.0  1.0

C C Se
C C Se 0 1 o o o 0 2 o o + 1 2 o o + 
C2Se is Indium-like structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two ethylselenurane molecules. C(1) is bonded in a 2-coordinate geometry to one C(1) and one Se(1) atom. The C(1)-C(1) bond length is 0.74 Å. The C(1)-Se(1) bond length is 1.19 Å. Se(1) is bonded in a 2-coordinate geometry to two equivalent C(1) atoms.