The compound described by K3Nb2AsSe11 crystallizes in the monoclinic Cc space group. There are three inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one As(1), one Se(10), one Se(2), one Se(5), one Se(9), and two equivalent Se(11) atoms. In the second K site, K(2) is bonded in a 9-coordinate geometry to one Se(1), one Se(3), one Se(6), one Se(8), one Se(9), two equivalent Se(10), and two equivalent Se(11) atoms. In the third K site, K(3) is bonded in a 7-coordinate geometry to one Se(10), one Se(3), one Se(5), one Se(6), one Se(8), and two equivalent Se(4) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted pentagonal bipyramidal geometry to one Se(1), one Se(10), one Se(2), one Se(3), one Se(5), one Se(7), and one Se(8) atom. In the second Nb site, Nb(2) is bonded in a 7-coordinate geometry to one Se(1), one Se(11), one Se(2), one Se(3), one Se(4), one Se(6), and one Se(9) atom. As(1) is bonded in a 4-coordinate geometry to one K(1), one Se(4), one Se(5), and one Se(7) atom. There are eleven inequivalent Se sites. In the first Se site, Se(5) is bonded in a distorted L-shaped geometry to one K(1), one K(3), one Nb(1), and one As(1) atom. In the second Se site, Se(6) is bonded in a 4-coordinate geometry to one K(2), one K(3), one Nb(2), and one Se(1) atom. In the third Se site, Se(7) is bonded in an L-shaped geometry to one Nb(1) and one As(1) atom. In the fourth Se site, Se(8) is bonded in a 4-coordinate geometry to one K(2), one K(3), one Nb(1), and one Se(3) atom. In the fifth Se site, Se(9) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Nb(2), and one Se(2) atom. In the sixth Se site, Se(10) is bonded in a 5-coordinate geometry to one K(1), one K(3), two equivalent K(2), and one Nb(1) atom. In the seventh Se site, Se(11) is bonded in a 5-coordinate geometry to two equivalent K(1), two equivalent K(2), and one Nb(2) atom. In the eighth Se site, Se(1) is bonded in a 4-coordinate geometry to one K(2), one Nb(1), one Nb(2), and one Se(6) atom. In the ninth Se site, Se(2) is bonded in a 2-coordinate geometry to one K(1), one Nb(1), one Nb(2), and one Se(9) atom. In the tenth Se site, Se(3) is bonded in a 5-coordinate geometry to one K(2), one K(3), one Nb(1), one Nb(2), and one Se(8) atom. In the eleventh Se site, Se(4) is bonded in a 4-coordinate geometry to two equivalent K(3), one Nb(2), and one As(1) atom. is represented by the CIF file [CIF]
data_K3Nb2AsSe11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.145
_cell_length_b   10.145
_cell_length_c   10.097
_cell_angle_alpha   82.850
_cell_angle_beta   82.850
_cell_angle_gamma   82.473
_symmetry_Int_Tables_number   1
_cell_volume   1016.010
_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  0.899  0.056  0.750  1.0
  K  K1  1  0.056  0.899  0.250  1.0
  K  K2  1  0.801  0.663  0.916  1.0
  K  K3  1  0.663  0.801  0.416  1.0
  K  K4  1  0.272  0.431  0.165  1.0
  K  K5  1  0.431  0.272  0.665  1.0
  Nb  Nb6  1  0.410  0.827  0.831  1.0
  Nb  Nb7  1  0.827  0.410  0.331  1.0
  Nb  Nb8  1  0.158  0.709  0.646  1.0
  Nb  Nb9  1  0.709  0.158  0.146  1.0
  As  As10  1  0.046  0.351  0.598  1.0
  As  As11  1  0.351  0.046  0.098  1.0
  Se  Se12  1  0.141  0.740  0.904  1.0
  Se  Se13  1  0.740  0.141  0.404  1.0
  Se  Se14  1  0.259  0.944  0.627  1.0
  Se  Se15  1  0.944  0.259  0.127  1.0
  Se  Se16  1  0.441  0.640  0.668  1.0
  Se  Se17  1  0.640  0.441  0.168  1.0
  Se  Se18  1  0.199  0.507  0.492  1.0
  Se  Se19  1  0.507  0.199  0.992  1.0
  Se  Se20  1  0.226  0.033  0.905  1.0
  Se  Se21  1  0.033  0.226  0.405  1.0
  Se  Se22  1  0.132  0.519  0.844  1.0
  Se  Se23  1  0.519  0.132  0.344  1.0
  Se  Se24  1  0.442  0.815  0.089  1.0
  Se  Se25  1  0.815  0.442  0.589  1.0
  Se  Se26  1  0.493  0.575  0.892  1.0
  Se  Se27  1  0.575  0.493  0.392  1.0
  Se  Se28  1  0.311  0.816  0.439  1.0
  Se  Se29  1  0.816  0.311  0.939  1.0
  Se  Se30  1  0.597  0.942  0.747  1.0
  Se  Se31  1  0.942  0.597  0.247  1.0
  Se  Se32  1  0.938  0.785  0.587  1.0
  Se  Se33  1  0.785  0.938  0.087  1.0
[/CIF]
.
The compound described by K3Nb2AsSe11 crystallizes in the monoclinic Cc space group. There are three inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one As(1), one Se(10), one Se(2), one Se(5), one Se(9), and two equivalent Se(11) atoms. In the second K site, K(2) is bonded in a 9-coordinate geometry to one Se(1), one Se(3), one Se(6), one Se(8), one Se(9), two equivalent Se(10), and two equivalent Se(11) atoms. In the third K site, K(3) is bonded in a 7-coordinate geometry to one Se(10), one Se(3), one Se(5), one Se(6), one Se(8), and two equivalent Se(4) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted pentagonal bipyramidal geometry to one Se(1), one Se(10), one Se(2), one Se(3), one Se(5), one Se(7), and one Se(8) atom. In the second Nb site, Nb(2) is bonded in a 7-coordinate geometry to one Se(1), one Se(11), one Se(2), one Se(3), one Se(4), one Se(6), and one Se(9) atom. As(1) is bonded in a 4-coordinate geometry to one K(1), one Se(4), one Se(5), and one Se(7) atom. There are eleven inequivalent Se sites. In the first Se site, Se(5) is bonded in a distorted L-shaped geometry to one K(1), one K(3), one Nb(1), and one As(1) atom. In the second Se site, Se(6) is bonded in a 4-coordinate geometry to one K(2), one K(3), one Nb(2), and one Se(1) atom. In the third Se site, Se(7) is bonded in an L-shaped geometry to one Nb(1) and one As(1) atom. In the fourth Se site, Se(8) is bonded in a 4-coordinate geometry to one K(2), one K(3), one Nb(1), and one Se(3) atom. In the fifth Se site, Se(9) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Nb(2), and one Se(2) atom. In the sixth Se site, Se(10) is bonded in a 5-coordinate geometry to one K(1), one K(3), two equivalent K(2), and one Nb(1) atom. In the seventh Se site, Se(11) is bonded in a 5-coordinate geometry to two equivalent K(1), two equivalent K(2), and one Nb(2) atom. In the eighth Se site, Se(1) is bonded in a 4-coordinate geometry to one K(2), one Nb(1), one Nb(2), and one Se(6) atom. In the ninth Se site, Se(2) is bonded in a 2-coordinate geometry to one K(1), one Nb(1), one Nb(2), and one Se(9) atom. In the tenth Se site, Se(3) is bonded in a 5-coordinate geometry to one K(2), one K(3), one Nb(1), one Nb(2), and one Se(8) atom. In the eleventh Se site, Se(4) is bonded in a 4-coordinate geometry to two equivalent K(3), one Nb(2), and one As(1) atom. is represented by the CIF file [CIF]
data_K3Nb2AsSe11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.145
_cell_length_b   10.145
_cell_length_c   10.097
_cell_angle_alpha   82.850
_cell_angle_beta   82.850
_cell_angle_gamma   82.473
_symmetry_Int_Tables_number   1
_cell_volume   1016.010
_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  0.899  0.056  0.750  1.0
  K  K1  1  0.056  0.899  0.250  1.0
  K  K2  1  0.801  0.663  0.916  1.0
  K  K3  1  0.663  0.801  0.416  1.0
  K  K4  1  0.272  0.431  0.165  1.0
  K  K5  1  0.431  0.272  0.665  1.0
  Nb  Nb6  1  0.410  0.827  0.831  1.0
  Nb  Nb7  1  0.827  0.410  0.331  1.0
  Nb  Nb8  1  0.158  0.709  0.646  1.0
  Nb  Nb9  1  0.709  0.158  0.146  1.0
  As  As10  1  0.046  0.351  0.598  1.0
  As  As11  1  0.351  0.046  0.098  1.0
  Se  Se12  1  0.141  0.740  0.904  1.0
  Se  Se13  1  0.740  0.141  0.404  1.0
  Se  Se14  1  0.259  0.944  0.627  1.0
  Se  Se15  1  0.944  0.259  0.127  1.0
  Se  Se16  1  0.441  0.640  0.668  1.0
  Se  Se17  1  0.640  0.441  0.168  1.0
  Se  Se18  1  0.199  0.507  0.492  1.0
  Se  Se19  1  0.507  0.199  0.992  1.0
  Se  Se20  1  0.226  0.033  0.905  1.0
  Se  Se21  1  0.033  0.226  0.405  1.0
  Se  Se22  1  0.132  0.519  0.844  1.0
  Se  Se23  1  0.519  0.132  0.344  1.0
  Se  Se24  1  0.442  0.815  0.089  1.0
  Se  Se25  1  0.815  0.442  0.589  1.0
  Se  Se26  1  0.493  0.575  0.892  1.0
  Se  Se27  1  0.575  0.493  0.392  1.0
  Se  Se28  1  0.311  0.816  0.439  1.0
  Se  Se29  1  0.816  0.311  0.939  1.0
  Se  Se30  1  0.597  0.942  0.747  1.0
  Se  Se31  1  0.942  0.597  0.247  1.0
  Se  Se32  1  0.938  0.785  0.587  1.0
  Se  Se33  1  0.785  0.938  0.087  1.0
[/CIF]
.