The structure described by Cs3H(SeO4)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 12-coordinate geometry to two equivalent H(1), two equivalent O(1), two equivalent O(3), two equivalent O(4), and four equivalent O(2) atoms. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(4), three equivalent O(1), and three equivalent O(3) atoms. H(1) is bonded in a linear geometry to two equivalent Cs(1) and two equivalent O(2) atoms. Se(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(3) is bonded in a distorted single-bond geometry to one Cs(1), three equivalent Cs(2), and one Se(1) atom. In the second O site, O(4) is bonded in a distorted single-bond geometry to one Cs(1), two equivalent Cs(2), and one Se(1) atom. In the third O site, O(1) is bonded in a distorted single-bond geometry to one Cs(1), three equivalent Cs(2), and one Se(1) atom. In the fourth O site, O(2) is bonded in a distorted water-like geometry to one Cs(2), two equivalent Cs(1), one H(1), and one Se(1) atom. is represented by the CIF file [CIF]
data_Cs3H(SeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.860
_cell_length_b   8.860
_cell_length_c   11.241
_cell_angle_alpha   78.989
_cell_angle_beta   78.989
_cell_angle_gamma   43.052
_symmetry_Int_Tables_number   1
_cell_volume   589.547
_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
  Cs  Cs0  1  0.746  0.254  0.250  1.0
  Cs  Cs1  1  0.254  0.746  0.750  1.0
  Cs  Cs2  1  0.916  0.466  0.848  1.0
  Cs  Cs3  1  0.466  0.916  0.348  1.0
  Cs  Cs4  1  0.084  0.534  0.152  1.0
  Cs  Cs5  1  0.534  0.084  0.652  1.0
  H  H6  1  0.000  0.000  0.000  1.0
  H  H7  1  0.000  0.000  0.500  1.0
  Se  Se8  1  0.329  0.902  0.035  1.0
  Se  Se9  1  0.902  0.329  0.535  1.0
  Se  Se10  1  0.671  0.098  0.965  1.0
  Se  Se11  1  0.098  0.671  0.465  1.0
  O  O12  1  0.172  0.139  0.099  1.0
  O  O13  1  0.139  0.172  0.599  1.0
  O  O14  1  0.828  0.861  0.901  1.0
  O  O15  1  0.861  0.828  0.401  1.0
  O  O16  1  0.172  0.848  0.050  1.0
  O  O17  1  0.848  0.172  0.550  1.0
  O  O18  1  0.828  0.152  0.950  1.0
  O  O19  1  0.152  0.828  0.450  1.0
  O  O20  1  0.384  0.924  0.886  1.0
  O  O21  1  0.924  0.384  0.386  1.0
  O  O22  1  0.616  0.076  0.114  1.0
  O  O23  1  0.076  0.616  0.614  1.0
  O  O24  1  0.558  0.688  0.105  1.0
  O  O25  1  0.688  0.558  0.605  1.0
  O  O26  1  0.442  0.312  0.895  1.0
  O  O27  1  0.312  0.442  0.395  1.0
[/CIF]
.
The structure described by Cs3H(SeO4)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 12-coordinate geometry to two equivalent H(1), two equivalent O(1), two equivalent O(3), two equivalent O(4), and four equivalent O(2) atoms. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(4), three equivalent O(1), and three equivalent O(3) atoms. H(1) is bonded in a linear geometry to two equivalent Cs(1) and two equivalent O(2) atoms. Se(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(3) is bonded in a distorted single-bond geometry to one Cs(1), three equivalent Cs(2), and one Se(1) atom. In the second O site, O(4) is bonded in a distorted single-bond geometry to one Cs(1), two equivalent Cs(2), and one Se(1) atom. In the third O site, O(1) is bonded in a distorted single-bond geometry to one Cs(1), three equivalent Cs(2), and one Se(1) atom. In the fourth O site, O(2) is bonded in a distorted water-like geometry to one Cs(2), two equivalent Cs(1), one H(1), and one Se(1) atom. is represented by the CIF file [CIF]
data_Cs3H(SeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.860
_cell_length_b   8.860
_cell_length_c   11.241
_cell_angle_alpha   78.989
_cell_angle_beta   78.989
_cell_angle_gamma   43.052
_symmetry_Int_Tables_number   1
_cell_volume   589.547
_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
  Cs  Cs0  1  0.746  0.254  0.250  1.0
  Cs  Cs1  1  0.254  0.746  0.750  1.0
  Cs  Cs2  1  0.916  0.466  0.848  1.0
  Cs  Cs3  1  0.466  0.916  0.348  1.0
  Cs  Cs4  1  0.084  0.534  0.152  1.0
  Cs  Cs5  1  0.534  0.084  0.652  1.0
  H  H6  1  0.000  0.000  0.000  1.0
  H  H7  1  0.000  0.000  0.500  1.0
  Se  Se8  1  0.329  0.902  0.035  1.0
  Se  Se9  1  0.902  0.329  0.535  1.0
  Se  Se10  1  0.671  0.098  0.965  1.0
  Se  Se11  1  0.098  0.671  0.465  1.0
  O  O12  1  0.172  0.139  0.099  1.0
  O  O13  1  0.139  0.172  0.599  1.0
  O  O14  1  0.828  0.861  0.901  1.0
  O  O15  1  0.861  0.828  0.401  1.0
  O  O16  1  0.172  0.848  0.050  1.0
  O  O17  1  0.848  0.172  0.550  1.0
  O  O18  1  0.828  0.152  0.950  1.0
  O  O19  1  0.152  0.828  0.450  1.0
  O  O20  1  0.384  0.924  0.886  1.0
  O  O21  1  0.924  0.384  0.386  1.0
  O  O22  1  0.616  0.076  0.114  1.0
  O  O23  1  0.076  0.616  0.614  1.0
  O  O24  1  0.558  0.688  0.105  1.0
  O  O25  1  0.688  0.558  0.605  1.0
  O  O26  1  0.442  0.312  0.895  1.0
  O  O27  1  0.312  0.442  0.395  1.0
[/CIF]
.