The compound described by CaCr4(HgO4)2 crystallizes in the trigonal R-3m space group. Ca(1) is bonded to six equivalent O(2) atoms to form distorted CaO6 octahedra that share edges with six equivalent Cr(1)O6 octahedra. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CrO6 octahedra that share edges with two equivalent Ca(1)O6 octahedra and edges with four equivalent Cr(1)O6 octahedra. In the second Cr site, Cr(2) is bonded in a 6-coordinate geometry to six equivalent O(2) atoms. Hg(1) is bonded in a 4-coordinate geometry to one O(1) and three equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Cr(1) and one Hg(1) atom to form OCr3Hg tetrahedra that share corners with three equivalent O(1)Cr3Hg tetrahedra, corners with nine equivalent O(2)CaCr3Hg trigonal bipyramids, and edges with three equivalent O(2)CaCr3Hg trigonal bipyramids. In the second O site, O(2) is bonded to one Ca(1), one Cr(2), two equivalent Cr(1), and one Hg(1) atom to form distorted OCaCr3Hg trigonal bipyramids that share corners with three equivalent O(1)Cr3Hg tetrahedra, corners with six equivalent O(2)CaCr3Hg trigonal bipyramids,  an edgeedge with one O(1)Cr3Hg tetrahedra, and edges with six equivalent O(2)CaCr3Hg trigonal bipyramids. is represented by the CIF card [CIF]
data_CaCr4(HgO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.798
_cell_length_b   6.797
_cell_length_c   6.797
_cell_angle_alpha   54.564
_cell_angle_beta   54.560
_cell_angle_gamma   54.561
_symmetry_Int_Tables_number   1
_cell_volume   193.903
_cell_formula_units_Z   1
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
  Ca  Ca0  1  0.500  0.500  0.500  1.0
  Cr  Cr1  1  1.000  0.500  0.000  1.0
  Cr  Cr2  1  0.500  1.000  0.000  1.0
  Cr  Cr3  1  1.000  1.000  0.500  1.0
  Cr  Cr4  1  0.000  0.000  0.000  1.0
  Hg  Hg5  1  0.660  0.660  0.660  1.0
  Hg  Hg6  1  0.340  0.340  0.340  1.0
  O  O7  1  0.784  0.784  0.784  1.0
  O  O8  1  0.241  0.241  0.804  1.0
  O  O9  1  0.241  0.804  0.241  1.0
  O  O10  1  0.805  0.241  0.241  1.0
  O  O11  1  0.759  0.196  0.759  1.0
  O  O12  1  0.196  0.759  0.759  1.0
  O  O13  1  0.216  0.216  0.216  1.0
  O  O14  1  0.759  0.759  0.196  1.0
[/CIF]
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The compound described by CaCr4(HgO4)2 crystallizes in the trigonal R-3m space group. Ca(1) is bonded to six equivalent O(2) atoms to form distorted CaO6 octahedra that share edges with six equivalent Cr(1)O6 octahedra. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CrO6 octahedra that share edges with two equivalent Ca(1)O6 octahedra and edges with four equivalent Cr(1)O6 octahedra. In the second Cr site, Cr(2) is bonded in a 6-coordinate geometry to six equivalent O(2) atoms. Hg(1) is bonded in a 4-coordinate geometry to one O(1) and three equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Cr(1) and one Hg(1) atom to form OCr3Hg tetrahedra that share corners with three equivalent O(1)Cr3Hg tetrahedra, corners with nine equivalent O(2)CaCr3Hg trigonal bipyramids, and edges with three equivalent O(2)CaCr3Hg trigonal bipyramids. In the second O site, O(2) is bonded to one Ca(1), one Cr(2), two equivalent Cr(1), and one Hg(1) atom to form distorted OCaCr3Hg trigonal bipyramids that share corners with three equivalent O(1)Cr3Hg tetrahedra, corners with six equivalent O(2)CaCr3Hg trigonal bipyramids,  an edgeedge with one O(1)Cr3Hg tetrahedra, and edges with six equivalent O(2)CaCr3Hg trigonal bipyramids. is represented by the CIF card [CIF]
data_CaCr4(HgO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.798
_cell_length_b   6.797
_cell_length_c   6.797
_cell_angle_alpha   54.564
_cell_angle_beta   54.560
_cell_angle_gamma   54.561
_symmetry_Int_Tables_number   1
_cell_volume   193.903
_cell_formula_units_Z   1
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
  Ca  Ca0  1  0.500  0.500  0.500  1.0
  Cr  Cr1  1  1.000  0.500  0.000  1.0
  Cr  Cr2  1  0.500  1.000  0.000  1.0
  Cr  Cr3  1  1.000  1.000  0.500  1.0
  Cr  Cr4  1  0.000  0.000  0.000  1.0
  Hg  Hg5  1  0.660  0.660  0.660  1.0
  Hg  Hg6  1  0.340  0.340  0.340  1.0
  O  O7  1  0.784  0.784  0.784  1.0
  O  O8  1  0.241  0.241  0.804  1.0
  O  O9  1  0.241  0.804  0.241  1.0
  O  O10  1  0.805  0.241  0.241  1.0
  O  O11  1  0.759  0.196  0.759  1.0
  O  O12  1  0.196  0.759  0.759  1.0
  O  O13  1  0.216  0.216  0.216  1.0
  O  O14  1  0.759  0.759  0.196  1.0
[/CIF]
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