The crystal structure described by FeH2SO5 crystallizes in the monoclinic C2 space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(10), one O(2), one O(5), one O(6), and one O(8) atom to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one S(2)O4 tetrahedra,  a cornercorner with one S(3)O4 tetrahedra, and corners with two equivalent S(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. In the second Fe site, Fe(2) is bonded to one O(1), one O(11), one O(3), one O(4), one O(7), and one O(9) atom to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one S(2)O4 tetrahedra,  a cornercorner with one S(3)O4 tetrahedra, and corners with two equivalent S(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(1) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(2) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(3) atom. There are three inequivalent S sites. In the first S site, S(1) is bonded to one O(4), one O(5), one O(8), and one O(9) atom to form SO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-48°. In the second S site, S(2) is bonded to two equivalent O(10) and two equivalent O(7) atoms to form SO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-48°. In the third S site, S(3) is bonded to two equivalent O(11) and two equivalent O(6) atoms to form SO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-48°. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a distorted water-like geometry to one Fe(1), one Fe(2), one H(1), and one H(2) atom. In the second O site, O(2) is bonded in a distorted water-like geometry to two equivalent Fe(1) and two equivalent H(3) atoms. In the third O site, O(3) is bonded in a distorted water-like geometry to two equivalent Fe(2) and two equivalent H(4) atoms. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one S(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one S(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one S(3) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one S(2) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Fe(1) and one S(1) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one Fe(2) and one S(1) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Fe(1) and one S(2) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one Fe(2) and one S(3) atom. is represented by the CIF file [CIF]
data_FeH2SO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.243
_cell_length_b   5.243
_cell_length_c   7.782
_cell_angle_alpha   106.623
_cell_angle_beta   106.625
_cell_angle_gamma   96.644
_symmetry_Int_Tables_number   1
_cell_volume   191.829
_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
  Fe  Fe0  1  1.000  0.000  0.500  1.0
  Fe  Fe1  1  0.500  0.500  0.000  1.0
  H  H2  1  0.626  0.053  0.209  1.0
  H  H3  1  0.447  0.874  0.291  1.0
  H  H4  1  0.375  0.947  0.791  1.0
  H  H5  1  0.553  0.125  0.709  1.0
  O  O6  1  0.610  0.890  0.250  1.0
  O  O7  1  0.390  0.110  0.750  1.0
  O  O8  1  0.217  0.324  0.103  1.0
  O  O9  1  0.176  0.283  0.397  1.0
  O  O10  1  0.783  0.676  0.897  1.0
  O  O11  1  0.824  0.717  0.603  1.0
  O  O12  1  0.170  0.717  0.339  1.0
  O  O13  1  0.783  0.330  0.161  1.0
  O  O14  1  0.830  0.283  0.661  1.0
  O  O15  1  0.217  0.670  0.839  1.0
  S  S16  1  0.089  0.411  0.250  1.0
  S  S17  1  0.911  0.589  0.750  1.0
[/CIF]
.
The crystal structure described by FeH2SO5 crystallizes in the monoclinic C2 space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(10), one O(2), one O(5), one O(6), and one O(8) atom to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one S(2)O4 tetrahedra,  a cornercorner with one S(3)O4 tetrahedra, and corners with two equivalent S(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. In the second Fe site, Fe(2) is bonded to one O(1), one O(11), one O(3), one O(4), one O(7), and one O(9) atom to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one S(2)O4 tetrahedra,  a cornercorner with one S(3)O4 tetrahedra, and corners with two equivalent S(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(1) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(2) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(3) atom. There are three inequivalent S sites. In the first S site, S(1) is bonded to one O(4), one O(5), one O(8), and one O(9) atom to form SO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-48°. In the second S site, S(2) is bonded to two equivalent O(10) and two equivalent O(7) atoms to form SO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-48°. In the third S site, S(3) is bonded to two equivalent O(11) and two equivalent O(6) atoms to form SO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-48°. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a distorted water-like geometry to one Fe(1), one Fe(2), one H(1), and one H(2) atom. In the second O site, O(2) is bonded in a distorted water-like geometry to two equivalent Fe(1) and two equivalent H(3) atoms. In the third O site, O(3) is bonded in a distorted water-like geometry to two equivalent Fe(2) and two equivalent H(4) atoms. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one S(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one S(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one S(3) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one S(2) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Fe(1) and one S(1) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one Fe(2) and one S(1) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Fe(1) and one S(2) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one Fe(2) and one S(3) atom. is represented by the CIF file [CIF]
data_FeH2SO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.243
_cell_length_b   5.243
_cell_length_c   7.782
_cell_angle_alpha   106.623
_cell_angle_beta   106.625
_cell_angle_gamma   96.644
_symmetry_Int_Tables_number   1
_cell_volume   191.829
_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
  Fe  Fe0  1  1.000  0.000  0.500  1.0
  Fe  Fe1  1  0.500  0.500  0.000  1.0
  H  H2  1  0.626  0.053  0.209  1.0
  H  H3  1  0.447  0.874  0.291  1.0
  H  H4  1  0.375  0.947  0.791  1.0
  H  H5  1  0.553  0.125  0.709  1.0
  O  O6  1  0.610  0.890  0.250  1.0
  O  O7  1  0.390  0.110  0.750  1.0
  O  O8  1  0.217  0.324  0.103  1.0
  O  O9  1  0.176  0.283  0.397  1.0
  O  O10  1  0.783  0.676  0.897  1.0
  O  O11  1  0.824  0.717  0.603  1.0
  O  O12  1  0.170  0.717  0.339  1.0
  O  O13  1  0.783  0.330  0.161  1.0
  O  O14  1  0.830  0.283  0.661  1.0
  O  O15  1  0.217  0.670  0.839  1.0
  S  S16  1  0.089  0.411  0.250  1.0
  S  S17  1  0.911  0.589  0.750  1.0
[/CIF]
.