data_CuSnSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.79
_cell_length_b   4.85
_cell_length_c   5.22
_cell_angle_alpha   90.0
_cell_angle_beta   107.89
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CuSnSe2
_chemical_formula_sum   'Cu1 Sn1 Se2'
_cell_volume   91.21
_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
  Cu  Cu0  1  0.1  0.0  0.27  1.0
  Sn  Sn3  1  0.39  0.43  0.15  1.0
  Se  Se1  1  0.3  0.43  0.26  1.0
  Se  Se2  1  0.78  0.0  0.74  1.0

data_CuSnSe2
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.79
_cell_length_b   4.85
_cell_length_c   5.22
_cell_angle_alpha   90.0
_cell_angle_beta   107.89
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CuSnSe2
_chemical_formula_sum   'Cu1 Sn1 Se2'
_cell_volume   91.21
_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
  Cu  Cu0  1  0.1  0.0  0.27  1.0
  Sn  Sn1  1  0.39  0.43  0.15  1.0
  Se  Se2  1  0.3  0.43  0.26  1.0
  Se  Se3  1  0.78  0.0  0.74  1.0

Cu Sn Se Se
Cu Sn Se Se 0 3 - o - 0 3 o o o 0 3 - o o 0 2 o o o 0 1 o o o 1 2 o o o 1 3 - o - 2 3 o o o 2 3 - o - 
CuSnSe2 crystallizes in the triclinic P1 space group. Cu(1) is bonded in a 5-coordinate geometry to two equivalent Se(1) and three equivalent Se(2) atoms. There is one shorter (2.21 Å) and one longer (2.90 Å) Cu(1)-Se(1) bond length. There are a spread of Cu(1)-Se(2) bond distances ranging from 2.66-3.05 Å. Sn(1) is bonded in a single-bond geometry to one Se(1) atom. The Sn(1)-Se(1) bond length is 0.71 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to two equivalent Cu(1) and one Sn(1) atom. In the second Se site, Se(2) is bonded in a 3-coordinate geometry to three equivalent Cu(1) atoms.