data_K(NbBi)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.34
_cell_length_b   7.34
_cell_length_c   7.34
_cell_angle_alpha   137.46
_cell_angle_beta   137.46
_cell_angle_gamma   61.73
_symmetry_Int_Tables_number   1
_chemical_formula_structural   K(NbBi)2
_chemical_formula_sum   'K1 Nb2 Bi2'
_cell_volume   178.92
_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  K2  1  0.0  0.0  0.0  1.0
  Nb  Nb3  1  0.0  0.0  0.83  1.0
  Nb  Nb4  1  0.0  0.0  0.78  1.0
  Bi  Bi0  1  0.0  0.66  0.15  1.0
  Bi  Bi1  1  0.66  0.0  0.15  1.0

data_K(NbBi)2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   7.53
_cell_length_b   7.53
_cell_length_c   7.34
_cell_angle_alpha   90.0
_cell_angle_beta   120.87
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   K(NbBi)2
_chemical_formula_sum   'K2 Nb4 Bi4'
_cell_volume   357.84
_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  0.0  1.0
  Nb  Nb1  2  0.0  0.0  0.78  1.0
  Nb  Nb2  2  0.0  0.0  0.83  1.0
  Bi  Bi3  4  0.17  0.17  0.49  1.0

K Nb Nb Bi Bi
K(NbBi)2 crystallizes in the monoclinic Cm space group. K(1) is bonded in a distorted single-bond geometry to one Nb(1) and two equivalent Bi(1) atoms. The K(1)-Nb(1) bond length is 1.25 Å. Both K(1)-Bi(1) bond lengths are 3.37 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a linear geometry to one K(1) and one Nb(2) atom. The Nb(1)-Nb(2) bond length is 0.40 Å. In the second Nb site, Nb(2) is bonded in a distorted single-bond geometry to one Nb(1) and four equivalent Bi(1) atoms. There are two shorter (3.23 Å) and two longer (3.40 Å) Nb(2)-Bi(1) bond lengths. Bi(1) is bonded in a 4-coordinate geometry to one K(1), two equivalent Nb(2), and one Bi(1) atom. The Bi(1)-Bi(1) bond length is 2.53 Å.