The compound described by NiH2SeO5 crystallizes in the triclinic P-1 space group. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with two equivalent Ni(2)O6 octahedra, corners with two equivalent Se(1)O5 trigonal bipyramids, and edges with two equivalent Se(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 27°. In the second Ni site, Ni(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Se(1)O5 trigonal bipyramids, and edges with two equivalent Se(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 27°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(2) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(3) and one O(5) atom. Se(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form SeO5 trigonal bipyramids that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(2)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, and  an edgeedge with one Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles are 33°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Ni(1), one Ni(2), and one Se(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Ni(2), one H(1), and one Se(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Ni(1), one H(2), and one Se(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Ni(2) and one Se(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ni(1), one H(2), and one Se(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_NiH2SeO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.170
_cell_length_b   7.965
_cell_length_c   5.167
_cell_angle_alpha   71.936
_cell_angle_beta   87.942
_cell_angle_gamma   71.967
_symmetry_Int_Tables_number   1
_cell_volume   191.904
_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
  Ni  Ni0  1  0.500  0.500  1.000  1.0
  Ni  Ni1  1  0.500  0.000  0.000  1.0
  H  H2  1  0.993  1.000  0.729  1.0
  H  H3  1  0.772  0.500  0.507  1.0
  H  H4  1  0.228  0.500  0.493  1.0
  H  H5  1  0.007  0.000  0.272  1.0
  Se  Se6  1  0.191  0.250  0.309  1.0
  Se  Se7  1  0.809  0.750  0.691  1.0
  O  O8  1  0.434  0.250  0.065  1.0
  O  O9  1  0.566  0.750  0.935  1.0
  O  O10  1  0.136  0.067  0.175  1.0
  O  O11  1  0.325  0.433  0.364  1.0
  O  O12  1  0.675  0.567  0.636  1.0
  O  O13  1  0.864  0.933  0.825  1.0
  O  O14  1  0.247  0.110  0.634  1.0
  O  O15  1  0.866  0.389  0.256  1.0
  O  O16  1  0.134  0.611  0.744  1.0
  O  O17  1  0.753  0.890  0.366  1.0
[/CIF]
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The compound described by NiH2SeO5 crystallizes in the triclinic P-1 space group. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with two equivalent Ni(2)O6 octahedra, corners with two equivalent Se(1)O5 trigonal bipyramids, and edges with two equivalent Se(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 27°. In the second Ni site, Ni(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Se(1)O5 trigonal bipyramids, and edges with two equivalent Se(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 27°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(2) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(3) and one O(5) atom. Se(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form SeO5 trigonal bipyramids that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(2)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, and  an edgeedge with one Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles are 33°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Ni(1), one Ni(2), and one Se(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Ni(2), one H(1), and one Se(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Ni(1), one H(2), and one Se(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Ni(2) and one Se(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ni(1), one H(2), and one Se(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_NiH2SeO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.170
_cell_length_b   7.965
_cell_length_c   5.167
_cell_angle_alpha   71.936
_cell_angle_beta   87.942
_cell_angle_gamma   71.967
_symmetry_Int_Tables_number   1
_cell_volume   191.904
_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
  Ni  Ni0  1  0.500  0.500  1.000  1.0
  Ni  Ni1  1  0.500  0.000  0.000  1.0
  H  H2  1  0.993  1.000  0.729  1.0
  H  H3  1  0.772  0.500  0.507  1.0
  H  H4  1  0.228  0.500  0.493  1.0
  H  H5  1  0.007  0.000  0.272  1.0
  Se  Se6  1  0.191  0.250  0.309  1.0
  Se  Se7  1  0.809  0.750  0.691  1.0
  O  O8  1  0.434  0.250  0.065  1.0
  O  O9  1  0.566  0.750  0.935  1.0
  O  O10  1  0.136  0.067  0.175  1.0
  O  O11  1  0.325  0.433  0.364  1.0
  O  O12  1  0.675  0.567  0.636  1.0
  O  O13  1  0.864  0.933  0.825  1.0
  O  O14  1  0.247  0.110  0.634  1.0
  O  O15  1  0.866  0.389  0.256  1.0
  O  O16  1  0.134  0.611  0.744  1.0
  O  O17  1  0.753  0.890  0.366  1.0
[/CIF]
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