data_K2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.78
_cell_length_b   9.78
_cell_length_c   6.99
_cell_angle_alpha   104.02
_cell_angle_beta   104.02
_cell_angle_gamma   23.67
_symmetry_Int_Tables_number   1
_chemical_formula_structural   K2Si
_chemical_formula_sum   'K4 Si2'
_cell_volume   260.25
_cell_formula_units_Z   2
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  0.24  0.0  0.53  1.0
  K  K1  1  0.3  0.0  0.31  1.0
  K  K2  1  0.12  0.0  0.47  1.0
  K  K3  1  0.18  0.0  0.25  1.0
  Si  Si4  1  0.56  0.0  0.12  1.0
  Si  Si5  1  0.86  0.0  0.65  1.0

data_K2Si
_symmetry_space_group_name_H-M   P-1
_cell_length_a   4.01
_cell_length_b   6.99
_cell_length_c   9.78
_cell_angle_alpha   104.02
_cell_angle_beta   101.84
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   K2Si
_chemical_formula_sum   'K4 Si2'
_cell_volume   260.25
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-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  2  0.0  0.08  0.91  1.0
  K  K1  2  0.0  0.14  0.03  1.0
  Si  Si2  2  0.0  0.27  0.65  1.0

K K K K Si Si
K2Si crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one K2Si cluster. There are two inequivalent K sites. In the first K site, K(1) is bonded in a distorted single-bond geometry to two equivalent K(2) atoms. There is one shorter (1.13 Å) and one longer (1.80 Å) K(1)-K(2) bond length. In the second K site, K(2) is bonded in a 3-coordinate geometry to two equivalent K(1) and one Si(1) atom. The K(2)-Si(1) bond length is 3.14 Å. Si(1) is bonded in a single-bond geometry to one K(2) atom.