The material structure described by K4Hg2Sn21 crystallizes in the orthorhombic Ama2 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 20-coordinate geometry to one Sn(2), one Sn(5), one Sn(7), one Sn(8), two equivalent Sn(1), two equivalent Sn(10), two equivalent Sn(11), two equivalent Sn(12), two equivalent Sn(3), two equivalent Sn(4), two equivalent Sn(6), and two equivalent Sn(9) atoms. In the second K site, K(2) is bonded in a 2-coordinate geometry to two equivalent Sn(5) and two equivalent Sn(7) atoms. In the third K site, K(3) is bonded in a 6-coordinate geometry to two equivalent Sn(3), two equivalent Sn(4), and two equivalent Sn(6) atoms. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to two equivalent Sn(3), two equivalent Sn(4), and two equivalent Sn(6) atoms. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded to two equivalent Sn(3) and two equivalent Sn(6) atoms to form HgSn4 tetrahedra that share corners with two equivalent Sn(11)KSn4 trigonal bipyramids and corners with two equivalent Sn(12)KSn4 trigonal bipyramids. In the second Hg site, Hg(2) is bonded to one Sn(5), one Sn(8), and two equivalent Sn(4) atoms to form HgSn4 tetrahedra that share corners with two equivalent Sn(11)KSn4 trigonal bipyramids and corners with two equivalent Sn(12)KSn4 trigonal bipyramids. There are thirteen inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 5-coordinate geometry to one K(1), one Sn(12), one Sn(13), one Sn(4), and one Sn(9) atom. In the second Sn site, Sn(2) is bonded in a 5-coordinate geometry to one K(1), one Sn(13), one Sn(8), and two equivalent Sn(9) atoms. In the third Sn site, Sn(3) is bonded in a 4-coordinate geometry to one K(1), one K(3), one K(4), one Hg(1), one Sn(11), one Sn(3), and one Sn(9) atom. In the fourth Sn site, Sn(4) is bonded to one K(1), one K(3), one K(4), one Hg(2), one Sn(1), one Sn(10), and one Sn(11) atom to form distorted SnK3Sn3Hg tetrahedra that share  a cornercorner with one Sn(4)K3Sn3Hg tetrahedra,  a cornercorner with one Sn(13)Sn4 tetrahedra, corners with two equivalent Sn(11)KSn4 trigonal bipyramids, corners with two equivalent Sn(12)KSn4 trigonal bipyramids,  an edgeedge with one Sn(12)KSn4 trigonal bipyramid, and  a faceface with one Sn(4)K3Sn3Hg tetrahedra. In the fifth Sn site, Sn(5) is bonded in a 6-coordinate geometry to one K(1), two equivalent K(2), one Hg(2), one Sn(7), and two equivalent Sn(10) atoms. In the sixth Sn site, Sn(6) is bonded in a 6-coordinate geometry to one K(1), one K(3), one K(4), one Hg(1), one Sn(10), one Sn(12), and one Sn(6) atom. In the seventh Sn site, Sn(7) is bonded in a 7-coordinate geometry to one K(1), two equivalent K(2), one Sn(13), one Sn(5), and two equivalent Sn(11) atoms. In the eighth Sn site, Sn(8) is bonded in a 4-coordinate geometry to one K(1), one Hg(2), one Sn(2), and two equivalent Sn(12) atoms. In the ninth Sn site, Sn(9) is bonded in a 5-coordinate geometry to one K(1), one Sn(1), one Sn(2), one Sn(3), and one Sn(9) atom. In the tenth Sn site, Sn(10) is bonded in a 5-coordinate geometry to one K(1), one Sn(10), one Sn(4), one Sn(5), and one Sn(6) atom. In the eleventh Sn site, Sn(11) is bonded to one K(1), one Sn(12), one Sn(3), one Sn(4), and one Sn(7) atom to form distorted SnKSn4 trigonal bipyramids that share  a cornercorner with one Hg(1)Sn4 tetrahedra,  a cornercorner with one Hg(2)Sn4 tetrahedra,  a cornercorner with one Sn(13)Sn4 tetrahedra, corners with two equivalent Sn(4)K3Sn3Hg tetrahedra, corners with two equivalent Sn(12)KSn4 trigonal bipyramids, and  an edgeedge with one Sn(11)KSn4 trigonal bipyramid. In the twelfth Sn site, Sn(12) is bonded to one K(1), one Sn(1), one Sn(11), one Sn(6), and one Sn(8) atom to form distorted SnKSn4 trigonal bipyramids that share  a cornercorner with one Hg(1)Sn4 tetrahedra,  a cornercorner with one Hg(2)Sn4 tetrahedra,  a cornercorner with one Sn(13)Sn4 tetrahedra, corners with two equivalent Sn(4)K3Sn3Hg tetrahedra, corners with two equivalent Sn(11)KSn4 trigonal bipyramids,  an edgeedge with one Sn(4)K3Sn3Hg tetrahedra, and  an edgeedge with one Sn(12)KSn4 trigonal bipyramid. In the thirteenth Sn site, Sn(13) is bonded to one Sn(2), one Sn(7), and two equivalent Sn(1) atoms to form SnSn4 tetrahedra that share corners with two equivalent Sn(4)K3Sn3Hg tetrahedra, corners with two equivalent Sn(11)KSn4 trigonal bipyramids, and corners with two equivalent Sn(12)KSn4 trigonal bipyramids. is represented by the CIF file [CIF]
data_K4Sn21Hg2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.298
_cell_length_b   12.298
_cell_length_c   12.292
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.052
_symmetry_Int_Tables_number   1
_cell_volume   1859.026
_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  0.499  0.999  0.250  1.0
  K  K1  1  0.001  0.501  0.750  1.0
  K  K2  1  0.476  0.524  0.000  1.0
  K  K3  1  0.018  0.233  0.250  1.0
  K  K4  1  0.767  0.982  0.750  1.0
  K  K5  1  0.476  0.524  0.500  1.0
  K  K6  1  0.020  0.765  0.250  1.0
  K  K7  1  0.235  0.980  0.750  1.0
  Sn  Sn8  1  0.500  0.116  0.943  1.0
  Sn  Sn9  1  0.616  0.308  0.250  1.0
  Sn  Sn10  1  0.814  1.000  0.133  1.0
  Sn  Sn11  1  0.501  0.880  0.565  1.0
  Sn  Sn12  1  0.380  0.688  0.250  1.0
  Sn  Sn13  1  0.189  0.000  0.368  1.0
  Sn  Sn14  1  0.616  0.693  0.250  1.0
  Sn  Sn15  1  0.814  1.000  0.367  1.0
  Sn  Sn16  1  0.381  0.316  0.250  1.0
  Sn  Sn17  1  0.189  0.000  0.132  1.0
  Sn  Sn18  1  0.501  0.880  0.935  1.0
  Sn  Sn19  1  0.500  0.116  0.557  1.0
  Sn  Sn20  1  0.000  0.186  0.867  1.0
  Sn  Sn21  1  0.120  0.499  0.065  1.0
  Sn  Sn22  1  0.307  0.384  0.750  1.0
  Sn  Sn23  1  1.000  0.811  0.632  1.0
  Sn  Sn24  1  0.884  0.500  0.443  1.0
  Sn  Sn25  1  0.684  0.619  0.750  1.0
  Sn  Sn26  1  0.120  0.499  0.435  1.0
  Sn  Sn27  1  0.312  0.620  0.750  1.0
  Sn  Sn28  1  0.884  0.500  0.057  1.0
  Sn  Sn29  1  0.692  0.384  0.750  1.0
  Sn  Sn30  1  0.000  0.186  0.633  1.0
  Sn  Sn31  1  1.000  0.811  0.868  1.0
  Sn  Sn32  1  0.685  0.182  0.067  1.0
  Sn  Sn33  1  0.318  0.818  0.433  1.0
  Sn  Sn34  1  0.684  0.819  0.434  1.0
  Sn  Sn35  1  0.317  0.184  0.068  1.0
  Sn  Sn36  1  0.318  0.818  0.067  1.0
  Sn  Sn37  1  0.685  0.182  0.433  1.0
  Sn  Sn38  1  0.317  0.184  0.432  1.0
  Sn  Sn39  1  0.684  0.819  0.066  1.0
  Sn  Sn40  1  0.181  0.316  0.934  1.0
  Sn  Sn41  1  0.816  0.683  0.568  1.0
  Sn  Sn42  1  0.182  0.682  0.567  1.0
  Sn  Sn43  1  0.818  0.315  0.933  1.0
  Sn  Sn44  1  0.818  0.315  0.567  1.0
  Sn  Sn45  1  0.182  0.682  0.933  1.0
  Sn  Sn46  1  0.816  0.683  0.932  1.0
  Sn  Sn47  1  0.181  0.316  0.566  1.0
  Sn  Sn48  1  0.500  0.250  0.750  1.0
  Sn  Sn49  1  0.750  0.500  0.250  1.0
  Hg  Hg50  1  0.001  0.999  0.000  1.0
  Hg  Hg51  1  0.499  0.749  0.750  1.0
  Hg  Hg52  1  0.251  0.501  0.250  1.0
  Hg  Hg53  1  0.001  0.999  0.500  1.0
[/CIF]
.
The material structure described by K4Hg2Sn21 crystallizes in the orthorhombic Ama2 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 20-coordinate geometry to one Sn(2), one Sn(5), one Sn(7), one Sn(8), two equivalent Sn(1), two equivalent Sn(10), two equivalent Sn(11), two equivalent Sn(12), two equivalent Sn(3), two equivalent Sn(4), two equivalent Sn(6), and two equivalent Sn(9) atoms. In the second K site, K(2) is bonded in a 2-coordinate geometry to two equivalent Sn(5) and two equivalent Sn(7) atoms. In the third K site, K(3) is bonded in a 6-coordinate geometry to two equivalent Sn(3), two equivalent Sn(4), and two equivalent Sn(6) atoms. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to two equivalent Sn(3), two equivalent Sn(4), and two equivalent Sn(6) atoms. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded to two equivalent Sn(3) and two equivalent Sn(6) atoms to form HgSn4 tetrahedra that share corners with two equivalent Sn(11)KSn4 trigonal bipyramids and corners with two equivalent Sn(12)KSn4 trigonal bipyramids. In the second Hg site, Hg(2) is bonded to one Sn(5), one Sn(8), and two equivalent Sn(4) atoms to form HgSn4 tetrahedra that share corners with two equivalent Sn(11)KSn4 trigonal bipyramids and corners with two equivalent Sn(12)KSn4 trigonal bipyramids. There are thirteen inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 5-coordinate geometry to one K(1), one Sn(12), one Sn(13), one Sn(4), and one Sn(9) atom. In the second Sn site, Sn(2) is bonded in a 5-coordinate geometry to one K(1), one Sn(13), one Sn(8), and two equivalent Sn(9) atoms. In the third Sn site, Sn(3) is bonded in a 4-coordinate geometry to one K(1), one K(3), one K(4), one Hg(1), one Sn(11), one Sn(3), and one Sn(9) atom. In the fourth Sn site, Sn(4) is bonded to one K(1), one K(3), one K(4), one Hg(2), one Sn(1), one Sn(10), and one Sn(11) atom to form distorted SnK3Sn3Hg tetrahedra that share  a cornercorner with one Sn(4)K3Sn3Hg tetrahedra,  a cornercorner with one Sn(13)Sn4 tetrahedra, corners with two equivalent Sn(11)KSn4 trigonal bipyramids, corners with two equivalent Sn(12)KSn4 trigonal bipyramids,  an edgeedge with one Sn(12)KSn4 trigonal bipyramid, and  a faceface with one Sn(4)K3Sn3Hg tetrahedra. In the fifth Sn site, Sn(5) is bonded in a 6-coordinate geometry to one K(1), two equivalent K(2), one Hg(2), one Sn(7), and two equivalent Sn(10) atoms. In the sixth Sn site, Sn(6) is bonded in a 6-coordinate geometry to one K(1), one K(3), one K(4), one Hg(1), one Sn(10), one Sn(12), and one Sn(6) atom. In the seventh Sn site, Sn(7) is bonded in a 7-coordinate geometry to one K(1), two equivalent K(2), one Sn(13), one Sn(5), and two equivalent Sn(11) atoms. In the eighth Sn site, Sn(8) is bonded in a 4-coordinate geometry to one K(1), one Hg(2), one Sn(2), and two equivalent Sn(12) atoms. In the ninth Sn site, Sn(9) is bonded in a 5-coordinate geometry to one K(1), one Sn(1), one Sn(2), one Sn(3), and one Sn(9) atom. In the tenth Sn site, Sn(10) is bonded in a 5-coordinate geometry to one K(1), one Sn(10), one Sn(4), one Sn(5), and one Sn(6) atom. In the eleventh Sn site, Sn(11) is bonded to one K(1), one Sn(12), one Sn(3), one Sn(4), and one Sn(7) atom to form distorted SnKSn4 trigonal bipyramids that share  a cornercorner with one Hg(1)Sn4 tetrahedra,  a cornercorner with one Hg(2)Sn4 tetrahedra,  a cornercorner with one Sn(13)Sn4 tetrahedra, corners with two equivalent Sn(4)K3Sn3Hg tetrahedra, corners with two equivalent Sn(12)KSn4 trigonal bipyramids, and  an edgeedge with one Sn(11)KSn4 trigonal bipyramid. In the twelfth Sn site, Sn(12) is bonded to one K(1), one Sn(1), one Sn(11), one Sn(6), and one Sn(8) atom to form distorted SnKSn4 trigonal bipyramids that share  a cornercorner with one Hg(1)Sn4 tetrahedra,  a cornercorner with one Hg(2)Sn4 tetrahedra,  a cornercorner with one Sn(13)Sn4 tetrahedra, corners with two equivalent Sn(4)K3Sn3Hg tetrahedra, corners with two equivalent Sn(11)KSn4 trigonal bipyramids,  an edgeedge with one Sn(4)K3Sn3Hg tetrahedra, and  an edgeedge with one Sn(12)KSn4 trigonal bipyramid. In the thirteenth Sn site, Sn(13) is bonded to one Sn(2), one Sn(7), and two equivalent Sn(1) atoms to form SnSn4 tetrahedra that share corners with two equivalent Sn(4)K3Sn3Hg tetrahedra, corners with two equivalent Sn(11)KSn4 trigonal bipyramids, and corners with two equivalent Sn(12)KSn4 trigonal bipyramids. is represented by the CIF file [CIF]
data_K4Sn21Hg2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.298
_cell_length_b   12.298
_cell_length_c   12.292
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.052
_symmetry_Int_Tables_number   1
_cell_volume   1859.026
_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  0.499  0.999  0.250  1.0
  K  K1  1  0.001  0.501  0.750  1.0
  K  K2  1  0.476  0.524  0.000  1.0
  K  K3  1  0.018  0.233  0.250  1.0
  K  K4  1  0.767  0.982  0.750  1.0
  K  K5  1  0.476  0.524  0.500  1.0
  K  K6  1  0.020  0.765  0.250  1.0
  K  K7  1  0.235  0.980  0.750  1.0
  Sn  Sn8  1  0.500  0.116  0.943  1.0
  Sn  Sn9  1  0.616  0.308  0.250  1.0
  Sn  Sn10  1  0.814  1.000  0.133  1.0
  Sn  Sn11  1  0.501  0.880  0.565  1.0
  Sn  Sn12  1  0.380  0.688  0.250  1.0
  Sn  Sn13  1  0.189  0.000  0.368  1.0
  Sn  Sn14  1  0.616  0.693  0.250  1.0
  Sn  Sn15  1  0.814  1.000  0.367  1.0
  Sn  Sn16  1  0.381  0.316  0.250  1.0
  Sn  Sn17  1  0.189  0.000  0.132  1.0
  Sn  Sn18  1  0.501  0.880  0.935  1.0
  Sn  Sn19  1  0.500  0.116  0.557  1.0
  Sn  Sn20  1  0.000  0.186  0.867  1.0
  Sn  Sn21  1  0.120  0.499  0.065  1.0
  Sn  Sn22  1  0.307  0.384  0.750  1.0
  Sn  Sn23  1  1.000  0.811  0.632  1.0
  Sn  Sn24  1  0.884  0.500  0.443  1.0
  Sn  Sn25  1  0.684  0.619  0.750  1.0
  Sn  Sn26  1  0.120  0.499  0.435  1.0
  Sn  Sn27  1  0.312  0.620  0.750  1.0
  Sn  Sn28  1  0.884  0.500  0.057  1.0
  Sn  Sn29  1  0.692  0.384  0.750  1.0
  Sn  Sn30  1  0.000  0.186  0.633  1.0
  Sn  Sn31  1  1.000  0.811  0.868  1.0
  Sn  Sn32  1  0.685  0.182  0.067  1.0
  Sn  Sn33  1  0.318  0.818  0.433  1.0
  Sn  Sn34  1  0.684  0.819  0.434  1.0
  Sn  Sn35  1  0.317  0.184  0.068  1.0
  Sn  Sn36  1  0.318  0.818  0.067  1.0
  Sn  Sn37  1  0.685  0.182  0.433  1.0
  Sn  Sn38  1  0.317  0.184  0.432  1.0
  Sn  Sn39  1  0.684  0.819  0.066  1.0
  Sn  Sn40  1  0.181  0.316  0.934  1.0
  Sn  Sn41  1  0.816  0.683  0.568  1.0
  Sn  Sn42  1  0.182  0.682  0.567  1.0
  Sn  Sn43  1  0.818  0.315  0.933  1.0
  Sn  Sn44  1  0.818  0.315  0.567  1.0
  Sn  Sn45  1  0.182  0.682  0.933  1.0
  Sn  Sn46  1  0.816  0.683  0.932  1.0
  Sn  Sn47  1  0.181  0.316  0.566  1.0
  Sn  Sn48  1  0.500  0.250  0.750  1.0
  Sn  Sn49  1  0.750  0.500  0.250  1.0
  Hg  Hg50  1  0.001  0.999  0.000  1.0
  Hg  Hg51  1  0.499  0.749  0.750  1.0
  Hg  Hg52  1  0.251  0.501  0.250  1.0
  Hg  Hg53  1  0.001  0.999  0.500  1.0
[/CIF]
.