data_KPbSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.26
_cell_length_b   4.26
_cell_length_c   7.68
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   KPbSe2
_chemical_formula_sum   'K1 Pb1 Se2'
_cell_volume   139.23
_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
  K  K0  1  0.0  0.0  0.17  1.0
  Pb  Pb1  1  0.13  0.13  0.23  1.0
  Se  Se2  1  0.0  0.0  0.6  1.0
  Se  Se3  1  0.13  0.13  0.19  1.0

data_KPbSe2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.02
_cell_length_b   6.02
_cell_length_c   7.68
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   KPbSe2
_chemical_formula_sum   'K2 Pb2 Se4'
_cell_volume   278.46
_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
  K  K0  2  0.0  0.0  0.17  1.0
  Pb  Pb1  2  0.13  0.0  0.23  1.0
  Se  Se2  2  0.0  0.0  0.6  1.0
  Se  Se3  2  0.13  0.0  0.19  1.0

K Pb Se Se
KPbSe2 crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two KPbSe2 clusters. K(1) is bonded in a 2-coordinate geometry to one Pb(1), one Se(1), and one Se(2) atom. The K(1)-Pb(1) bond length is 0.90 Å. The K(1)-Se(1) bond length is 3.25 Å. The K(1)-Se(2) bond length is 0.79 Å. Pb(1) is bonded in a distorted single-bond geometry to one K(1), one Se(1), and one Se(2) atom. The Pb(1)-Se(1) bond length is 2.91 Å. The Pb(1)-Se(2) bond length is 0.29 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to one K(1) and one Pb(1) atom. In the second Se site, Se(2) is bonded in a distorted water-like geometry to one K(1) and one Pb(1) atom.