The compound described by Sm2HgO4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to two equivalent O(1), two equivalent O(2), and three equivalent O(4) atoms to form distorted edge-sharing SmO7 pentagonal bipyramids. In the second Sm site, Sm(2) is bonded in a 7-coordinate geometry to one O(1), one O(4), two equivalent O(2), and three equivalent O(3) atoms. Hg(1) is bonded in a linear geometry to one O(1) and one O(3) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Sm(2), two equivalent Sm(1), and one Hg(1) atom to form OSm3Hg tetrahedra that share corners with two equivalent O(1)Sm3Hg tetrahedra, corners with two equivalent O(2)Sm4 tetrahedra, corners with four equivalent O(3)Sm3Hg tetrahedra, corners with five equivalent O(4)Sm4 trigonal pyramids, edges with two equivalent O(2)Sm4 tetrahedra, and  an edgeedge with one O(4)Sm4 trigonal pyramid. In the second O site, O(2) is bonded to two equivalent Sm(1) and two equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with two equivalent O(1)Sm3Hg tetrahedra, corners with two equivalent O(2)Sm4 tetrahedra, corners with four equivalent O(3)Sm3Hg tetrahedra, corners with four equivalent O(4)Sm4 trigonal pyramids,  an edgeedge with one O(3)Sm3Hg tetrahedra,  an edgeedge with one O(2)Sm4 tetrahedra, edges with two equivalent O(1)Sm3Hg tetrahedra, and edges with two equivalent O(4)Sm4 trigonal pyramids. In the third O site, O(3) is bonded to three equivalent Sm(2) and one Hg(1) atom to form distorted OSm3Hg tetrahedra that share corners with two equivalent O(3)Sm3Hg tetrahedra, corners with four equivalent O(1)Sm3Hg tetrahedra, corners with four equivalent O(2)Sm4 tetrahedra, corners with three equivalent O(4)Sm4 trigonal pyramids,  an edgeedge with one O(2)Sm4 tetrahedra, and edges with two equivalent O(3)Sm3Hg tetrahedra. In the fourth O site, O(4) is bonded to one Sm(2) and three equivalent Sm(1) atoms to form distorted OSm4 trigonal pyramids that share corners with three equivalent O(3)Sm3Hg tetrahedra, corners with four equivalent O(2)Sm4 tetrahedra, corners with five equivalent O(1)Sm3Hg tetrahedra, corners with two equivalent O(4)Sm4 trigonal pyramids,  an edgeedge with one O(1)Sm3Hg tetrahedra, edges with two equivalent O(2)Sm4 tetrahedra, and edges with two equivalent O(4)Sm4 trigonal pyramids. is represented by the CIF card [CIF]
data_Sm2HgO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.144
_cell_length_b   7.144
_cell_length_c   10.214
_cell_angle_alpha   59.427
_cell_angle_beta   59.427
_cell_angle_gamma   30.336
_symmetry_Int_Tables_number   1
_cell_volume   223.789
_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
  Sm  Sm0  1  0.619  0.619  0.540  1.0
  Sm  Sm1  1  0.381  0.381  0.460  1.0
  Sm  Sm2  1  0.840  0.840  0.800  1.0
  Sm  Sm3  1  0.160  0.160  0.200  1.0
  Hg  Hg4  1  0.886  0.886  0.162  1.0
  Hg  Hg5  1  0.114  0.114  0.838  1.0
  O  O6  1  0.964  0.964  0.280  1.0
  O  O7  1  0.036  0.036  0.720  1.0
  O  O8  1  0.581  0.581  0.347  1.0
  O  O9  1  0.419  0.419  0.653  1.0
  O  O10  1  0.798  0.798  0.056  1.0
  O  O11  1  0.202  0.202  0.944  1.0
  O  O12  1  0.768  0.768  0.613  1.0
  O  O13  1  0.232  0.232  0.387  1.0
[/CIF]
.
The compound described by Sm2HgO4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to two equivalent O(1), two equivalent O(2), and three equivalent O(4) atoms to form distorted edge-sharing SmO7 pentagonal bipyramids. In the second Sm site, Sm(2) is bonded in a 7-coordinate geometry to one O(1), one O(4), two equivalent O(2), and three equivalent O(3) atoms. Hg(1) is bonded in a linear geometry to one O(1) and one O(3) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Sm(2), two equivalent Sm(1), and one Hg(1) atom to form OSm3Hg tetrahedra that share corners with two equivalent O(1)Sm3Hg tetrahedra, corners with two equivalent O(2)Sm4 tetrahedra, corners with four equivalent O(3)Sm3Hg tetrahedra, corners with five equivalent O(4)Sm4 trigonal pyramids, edges with two equivalent O(2)Sm4 tetrahedra, and  an edgeedge with one O(4)Sm4 trigonal pyramid. In the second O site, O(2) is bonded to two equivalent Sm(1) and two equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with two equivalent O(1)Sm3Hg tetrahedra, corners with two equivalent O(2)Sm4 tetrahedra, corners with four equivalent O(3)Sm3Hg tetrahedra, corners with four equivalent O(4)Sm4 trigonal pyramids,  an edgeedge with one O(3)Sm3Hg tetrahedra,  an edgeedge with one O(2)Sm4 tetrahedra, edges with two equivalent O(1)Sm3Hg tetrahedra, and edges with two equivalent O(4)Sm4 trigonal pyramids. In the third O site, O(3) is bonded to three equivalent Sm(2) and one Hg(1) atom to form distorted OSm3Hg tetrahedra that share corners with two equivalent O(3)Sm3Hg tetrahedra, corners with four equivalent O(1)Sm3Hg tetrahedra, corners with four equivalent O(2)Sm4 tetrahedra, corners with three equivalent O(4)Sm4 trigonal pyramids,  an edgeedge with one O(2)Sm4 tetrahedra, and edges with two equivalent O(3)Sm3Hg tetrahedra. In the fourth O site, O(4) is bonded to one Sm(2) and three equivalent Sm(1) atoms to form distorted OSm4 trigonal pyramids that share corners with three equivalent O(3)Sm3Hg tetrahedra, corners with four equivalent O(2)Sm4 tetrahedra, corners with five equivalent O(1)Sm3Hg tetrahedra, corners with two equivalent O(4)Sm4 trigonal pyramids,  an edgeedge with one O(1)Sm3Hg tetrahedra, edges with two equivalent O(2)Sm4 tetrahedra, and edges with two equivalent O(4)Sm4 trigonal pyramids. is represented by the CIF card [CIF]
data_Sm2HgO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.144
_cell_length_b   7.144
_cell_length_c   10.214
_cell_angle_alpha   59.427
_cell_angle_beta   59.427
_cell_angle_gamma   30.336
_symmetry_Int_Tables_number   1
_cell_volume   223.789
_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
  Sm  Sm0  1  0.619  0.619  0.540  1.0
  Sm  Sm1  1  0.381  0.381  0.460  1.0
  Sm  Sm2  1  0.840  0.840  0.800  1.0
  Sm  Sm3  1  0.160  0.160  0.200  1.0
  Hg  Hg4  1  0.886  0.886  0.162  1.0
  Hg  Hg5  1  0.114  0.114  0.838  1.0
  O  O6  1  0.964  0.964  0.280  1.0
  O  O7  1  0.036  0.036  0.720  1.0
  O  O8  1  0.581  0.581  0.347  1.0
  O  O9  1  0.419  0.419  0.653  1.0
  O  O10  1  0.798  0.798  0.056  1.0
  O  O11  1  0.202  0.202  0.944  1.0
  O  O12  1  0.768  0.768  0.613  1.0
  O  O13  1  0.232  0.232  0.387  1.0
[/CIF]
.