The crystal structure described by Y2HgO4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent O(3), two equivalent O(4), and three equivalent O(1) atoms to form distorted edge-sharing YO7 pentagonal bipyramids. In the second Y site, Y(2) is bonded in a 7-coordinate geometry to one O(1), one O(3), two equivalent O(4), and three equivalent O(2) atoms. Hg(1) is bonded in a linear geometry to one O(2) and one O(3) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Y(2) and three equivalent Y(1) atoms. In the second O site, O(2) is bonded to three equivalent Y(2) and one Hg(1) atom to form distorted OY3Hg tetrahedra that share corners with two equivalent O(2)Y3Hg tetrahedra, corners with four equivalent O(3)Y3Hg tetrahedra, corners with four equivalent O(4)Y4 tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, and edges with two equivalent O(2)Y3Hg tetrahedra. In the third O site, O(3) is bonded to one Y(2), two equivalent Y(1), and one Hg(1) atom to form OY3Hg tetrahedra that share corners with two equivalent O(3)Y3Hg tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with four equivalent O(2)Y3Hg tetrahedra, and edges with two equivalent O(4)Y4 tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(3)Y3Hg tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with four equivalent O(2)Y3Hg tetrahedra,  an edgeedge with one O(2)Y3Hg tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, and edges with two equivalent O(3)Y3Hg tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y2HgO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.606
_cell_length_b   7.035
_cell_length_c   8.779
_cell_angle_alpha   101.649
_cell_angle_beta   101.848
_cell_angle_gamma   75.144
_symmetry_Int_Tables_number   1
_cell_volume   208.033
_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
  Y  Y0  1  0.382  0.777  0.538  1.0
  Y  Y1  1  0.841  0.520  0.199  1.0
  Y  Y2  1  0.161  0.480  0.800  1.0
  Y  Y3  1  0.620  0.224  0.461  1.0
  Hg  Hg4  1  0.114  0.935  0.161  1.0
  Hg  Hg5  1  0.888  0.065  0.838  1.0
  O  O6  1  0.767  0.854  0.386  1.0
  O  O7  1  0.203  0.649  0.053  1.0
  O  O8  1  0.966  0.787  0.717  1.0
  O  O9  1  0.418  0.513  0.347  1.0
  O  O10  1  0.583  0.488  0.652  1.0
  O  O11  1  0.036  0.213  0.282  1.0
  O  O12  1  0.799  0.350  0.945  1.0
  O  O13  1  0.235  0.146  0.613  1.0
[/CIF]
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The crystal structure described by Y2HgO4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent O(3), two equivalent O(4), and three equivalent O(1) atoms to form distorted edge-sharing YO7 pentagonal bipyramids. In the second Y site, Y(2) is bonded in a 7-coordinate geometry to one O(1), one O(3), two equivalent O(4), and three equivalent O(2) atoms. Hg(1) is bonded in a linear geometry to one O(2) and one O(3) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Y(2) and three equivalent Y(1) atoms. In the second O site, O(2) is bonded to three equivalent Y(2) and one Hg(1) atom to form distorted OY3Hg tetrahedra that share corners with two equivalent O(2)Y3Hg tetrahedra, corners with four equivalent O(3)Y3Hg tetrahedra, corners with four equivalent O(4)Y4 tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, and edges with two equivalent O(2)Y3Hg tetrahedra. In the third O site, O(3) is bonded to one Y(2), two equivalent Y(1), and one Hg(1) atom to form OY3Hg tetrahedra that share corners with two equivalent O(3)Y3Hg tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with four equivalent O(2)Y3Hg tetrahedra, and edges with two equivalent O(4)Y4 tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(3)Y3Hg tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with four equivalent O(2)Y3Hg tetrahedra,  an edgeedge with one O(2)Y3Hg tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, and edges with two equivalent O(3)Y3Hg tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y2HgO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.606
_cell_length_b   7.035
_cell_length_c   8.779
_cell_angle_alpha   101.649
_cell_angle_beta   101.848
_cell_angle_gamma   75.144
_symmetry_Int_Tables_number   1
_cell_volume   208.033
_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
  Y  Y0  1  0.382  0.777  0.538  1.0
  Y  Y1  1  0.841  0.520  0.199  1.0
  Y  Y2  1  0.161  0.480  0.800  1.0
  Y  Y3  1  0.620  0.224  0.461  1.0
  Hg  Hg4  1  0.114  0.935  0.161  1.0
  Hg  Hg5  1  0.888  0.065  0.838  1.0
  O  O6  1  0.767  0.854  0.386  1.0
  O  O7  1  0.203  0.649  0.053  1.0
  O  O8  1  0.966  0.787  0.717  1.0
  O  O9  1  0.418  0.513  0.347  1.0
  O  O10  1  0.583  0.488  0.652  1.0
  O  O11  1  0.036  0.213  0.282  1.0
  O  O12  1  0.799  0.350  0.945  1.0
  O  O13  1  0.235  0.146  0.613  1.0
[/CIF]
.