data_K2As
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.21
_cell_length_b   6.21
_cell_length_c   6.19
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   59.77
_symmetry_Int_Tables_number   1
_chemical_formula_structural   K2As
_chemical_formula_sum   'K4 As2'
_cell_volume   206.17
_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  K2  1  0.01  0.51  0.64  1.0
  K  K3  1  0.76  0.49  0.55  1.0
  K  K4  1  0.76  0.51  0.64  1.0
  K  K5  1  0.01  0.49  0.55  1.0
  As  As0  1  0.38  0.41  0.64  1.0
  As  As1  1  0.38  0.59  0.55  1.0

data_K2As
_symmetry_space_group_name_H-M   P-1
_cell_length_a   6.19
_cell_length_b   6.19
_cell_length_c   6.21
_cell_angle_alpha   90.0
_cell_angle_beta   119.89
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   K2As
_chemical_formula_sum   'K4 As2'
_cell_volume   206.17
_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  0.49  0.45  0.12  1.0
  K  K1  2  0.49  0.45  0.87  1.0
  As  As2  2  0.41  0.55  0.41  1.0

K K K K As As
K K K K As As 0 3 o o o 1 2 o o o 4 5 o o o 
K2As is Hg_xSn structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one K2As cluster. There are two inequivalent K sites. In the first K site, K(1) is bonded in a distorted single-bond geometry to one K(2) and one As(1) atom. The K(1)-K(2) bond length is 0.60 Å. The K(1)-As(1) bond length is 2.09 Å. In the second K site, K(2) is bonded in a single-bond geometry to one K(1) atom. As(1) is bonded in a 2-coordinate geometry to one K(1) and one As(1) atom. The As(1)-As(1) bond length is 1.22 Å.