The compound described by KHSi2O5 crystallizes in the monoclinic C2/m space group. There are three inequivalent K sites. In the first K site, K(1) is bonded to four equivalent O(2) and four equivalent O(3) atoms to form distorted KO8 hexagonal bipyramids that share corners with four equivalent Si(1)O4 tetrahedra and edges with four equivalent Si(2)O4 tetrahedra. In the second K site, K(2) is bonded to four equivalent O(1) and four equivalent O(4) atoms to form distorted KO8 hexagonal bipyramids that share corners with four equivalent Si(2)O4 tetrahedra and edges with four equivalent Si(1)O4 tetrahedra. In the third K site, K(3) is bonded in a 8-coordinate geometry to two equivalent H(1), one O(5), one O(6), two equivalent O(1), and two equivalent O(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one K(1)O8 hexagonal bipyramid,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one K(2)O8 hexagonal bipyramid. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one K(2)O8 hexagonal bipyramid,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. H(1) is bonded in a linear geometry to one K(3), one O(1), and one O(2) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one K(2), one K(3), one Si(1), and one H(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(3), one Si(2), and one H(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one K(2), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one K(3) and two equivalent Si(2) atoms. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one K(3) and two equivalent Si(1) atoms. is represented by the CIF file [CIF]
data_KSi2HO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.523
_cell_length_b   8.523
_cell_length_c   9.894
_cell_angle_alpha   61.839
_cell_angle_beta   61.839
_cell_angle_gamma   59.616
_symmetry_Int_Tables_number   1
_cell_volume   520.329
_cell_formula_units_Z   4
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  0.000  0.000  0.000  1.0
  K  K1  1  0.000  0.000  0.500  1.0
  K  K2  1  0.680  0.680  0.981  1.0
  K  K3  1  0.320  0.320  0.019  1.0
  Si  Si4  1  0.116  0.489  0.676  1.0
  Si  Si5  1  0.489  0.116  0.676  1.0
  Si  Si6  1  0.884  0.511  0.324  1.0
  Si  Si7  1  0.511  0.884  0.324  1.0
  Si  Si8  1  0.782  0.408  0.702  1.0
  Si  Si9  1  0.408  0.782  0.702  1.0
  Si  Si10  1  0.218  0.592  0.298  1.0
  Si  Si11  1  0.592  0.218  0.298  1.0
  H  H12  1  0.684  0.147  0.799  1.0
  H  H13  1  0.147  0.684  0.799  1.0
  H  H14  1  0.316  0.853  0.201  1.0
  H  H15  1  0.853  0.316  0.201  1.0
  O  O16  1  0.039  0.639  0.767  1.0
  O  O17  1  0.639  0.039  0.767  1.0
  O  O18  1  0.961  0.361  0.233  1.0
  O  O19  1  0.361  0.961  0.233  1.0
  O  O20  1  0.720  0.227  0.833  1.0
  O  O21  1  0.227  0.720  0.833  1.0
  O  O22  1  0.280  0.773  0.167  1.0
  O  O23  1  0.773  0.280  0.167  1.0
  O  O24  1  0.963  0.386  0.737  1.0
  O  O25  1  0.386  0.963  0.737  1.0
  O  O26  1  0.037  0.614  0.263  1.0
  O  O27  1  0.614  0.037  0.263  1.0
  O  O28  1  0.156  0.595  0.480  1.0
  O  O29  1  0.595  0.156  0.480  1.0
  O  O30  1  0.844  0.405  0.520  1.0
  O  O31  1  0.405  0.844  0.520  1.0
  O  O32  1  0.611  0.611  0.729  1.0
  O  O33  1  0.389  0.389  0.271  1.0
  O  O34  1  0.313  0.313  0.711  1.0
  O  O35  1  0.687  0.687  0.289  1.0
[/CIF]
.
The compound described by KHSi2O5 crystallizes in the monoclinic C2/m space group. There are three inequivalent K sites. In the first K site, K(1) is bonded to four equivalent O(2) and four equivalent O(3) atoms to form distorted KO8 hexagonal bipyramids that share corners with four equivalent Si(1)O4 tetrahedra and edges with four equivalent Si(2)O4 tetrahedra. In the second K site, K(2) is bonded to four equivalent O(1) and four equivalent O(4) atoms to form distorted KO8 hexagonal bipyramids that share corners with four equivalent Si(2)O4 tetrahedra and edges with four equivalent Si(1)O4 tetrahedra. In the third K site, K(3) is bonded in a 8-coordinate geometry to two equivalent H(1), one O(5), one O(6), two equivalent O(1), and two equivalent O(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one K(1)O8 hexagonal bipyramid,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one K(2)O8 hexagonal bipyramid. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one K(2)O8 hexagonal bipyramid,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. H(1) is bonded in a linear geometry to one K(3), one O(1), and one O(2) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one K(2), one K(3), one Si(1), and one H(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(3), one Si(2), and one H(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one K(2), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one K(3) and two equivalent Si(2) atoms. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one K(3) and two equivalent Si(1) atoms. is represented by the CIF file [CIF]
data_KSi2HO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.523
_cell_length_b   8.523
_cell_length_c   9.894
_cell_angle_alpha   61.839
_cell_angle_beta   61.839
_cell_angle_gamma   59.616
_symmetry_Int_Tables_number   1
_cell_volume   520.329
_cell_formula_units_Z   4
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  0.000  0.000  0.000  1.0
  K  K1  1  0.000  0.000  0.500  1.0
  K  K2  1  0.680  0.680  0.981  1.0
  K  K3  1  0.320  0.320  0.019  1.0
  Si  Si4  1  0.116  0.489  0.676  1.0
  Si  Si5  1  0.489  0.116  0.676  1.0
  Si  Si6  1  0.884  0.511  0.324  1.0
  Si  Si7  1  0.511  0.884  0.324  1.0
  Si  Si8  1  0.782  0.408  0.702  1.0
  Si  Si9  1  0.408  0.782  0.702  1.0
  Si  Si10  1  0.218  0.592  0.298  1.0
  Si  Si11  1  0.592  0.218  0.298  1.0
  H  H12  1  0.684  0.147  0.799  1.0
  H  H13  1  0.147  0.684  0.799  1.0
  H  H14  1  0.316  0.853  0.201  1.0
  H  H15  1  0.853  0.316  0.201  1.0
  O  O16  1  0.039  0.639  0.767  1.0
  O  O17  1  0.639  0.039  0.767  1.0
  O  O18  1  0.961  0.361  0.233  1.0
  O  O19  1  0.361  0.961  0.233  1.0
  O  O20  1  0.720  0.227  0.833  1.0
  O  O21  1  0.227  0.720  0.833  1.0
  O  O22  1  0.280  0.773  0.167  1.0
  O  O23  1  0.773  0.280  0.167  1.0
  O  O24  1  0.963  0.386  0.737  1.0
  O  O25  1  0.386  0.963  0.737  1.0
  O  O26  1  0.037  0.614  0.263  1.0
  O  O27  1  0.614  0.037  0.263  1.0
  O  O28  1  0.156  0.595  0.480  1.0
  O  O29  1  0.595  0.156  0.480  1.0
  O  O30  1  0.844  0.405  0.520  1.0
  O  O31  1  0.405  0.844  0.520  1.0
  O  O32  1  0.611  0.611  0.729  1.0
  O  O33  1  0.389  0.389  0.271  1.0
  O  O34  1  0.313  0.313  0.711  1.0
  O  O35  1  0.687  0.687  0.289  1.0
[/CIF]
.