The material described by Rb4Ca(Se2O7)2 crystallizes in the monoclinic C2 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(1), one O(4), one O(5), one O(8), two equivalent O(2), and two equivalent O(3) atoms. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms. Ca(1) is bonded to one O(8), two equivalent O(1), two equivalent O(5), and two equivalent O(6) atoms to form distorted CaO7 pentagonal bipyramids that share edges with two equivalent Se(1)O4 tetrahedra and edges with two equivalent Se(2)O4 tetrahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form SeO4 tetrahedra that share  a cornercorner with one Se(1)O4 tetrahedra and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. In the second Se site, Se(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form SeO4 tetrahedra that share  a cornercorner with one Se(2)O4 tetrahedra and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(2), one Ca(1), and one Se(1) atom. In the second O site, O(2) is bonded to one Rb(2), two equivalent Rb(1), and one Se(2) atom to form distorted edge-sharing ORb3Se tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Rb(1), two equivalent Rb(2), and one Se(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(2), one Ca(1), and one Se(1) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to one Rb(2), one Ca(1), and one Se(2) atom. In the seventh O site, O(7) is bonded in a linear geometry to two equivalent Se(1) atoms. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to two equivalent Rb(1), one Ca(1), and two equivalent Se(2) atoms. is represented by the CIF file [CIF]
data_Rb4Ca(Se2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.383
_cell_length_b   8.383
_cell_length_c   8.052
_cell_angle_alpha   97.559
_cell_angle_beta   97.559
_cell_angle_gamma   59.048
_symmetry_Int_Tables_number   1
_cell_volume   479.659
_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
  Rb  Rb0  1  0.207  0.535  0.400  1.0
  Rb  Rb1  1  0.465  0.793  0.100  1.0
  Rb  Rb2  1  0.782  0.549  0.559  1.0
  Rb  Rb3  1  0.451  0.218  0.941  1.0
  Ca  Ca4  1  0.913  0.087  0.750  1.0
  Se  Se5  1  0.706  0.107  0.394  1.0
  Se  Se6  1  0.893  0.294  0.106  1.0
  Se  Se7  1  0.312  0.897  0.618  1.0
  Se  Se8  1  0.103  0.688  0.882  1.0
  O  O9  1  0.646  0.270  0.561  1.0
  O  O10  1  0.730  0.354  0.939  1.0
  O  O11  1  0.383  0.775  0.434  1.0
  O  O12  1  0.225  0.617  0.066  1.0
  O  O13  1  0.515  0.112  0.294  1.0
  O  O14  1  0.888  0.485  0.206  1.0
  O  O15  1  0.492  0.902  0.733  1.0
  O  O16  1  0.098  0.508  0.767  1.0
  O  O17  1  0.856  0.906  0.486  1.0
  O  O18  1  0.094  0.144  0.014  1.0
  O  O19  1  0.124  0.113  0.597  1.0
  O  O20  1  0.887  0.876  0.903  1.0
  O  O21  1  0.818  0.182  0.250  1.0
  O  O22  1  0.213  0.787  0.750  1.0
[/CIF]
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The material described by Rb4Ca(Se2O7)2 crystallizes in the monoclinic C2 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(1), one O(4), one O(5), one O(8), two equivalent O(2), and two equivalent O(3) atoms. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms. Ca(1) is bonded to one O(8), two equivalent O(1), two equivalent O(5), and two equivalent O(6) atoms to form distorted CaO7 pentagonal bipyramids that share edges with two equivalent Se(1)O4 tetrahedra and edges with two equivalent Se(2)O4 tetrahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form SeO4 tetrahedra that share  a cornercorner with one Se(1)O4 tetrahedra and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. In the second Se site, Se(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form SeO4 tetrahedra that share  a cornercorner with one Se(2)O4 tetrahedra and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(2), one Ca(1), and one Se(1) atom. In the second O site, O(2) is bonded to one Rb(2), two equivalent Rb(1), and one Se(2) atom to form distorted edge-sharing ORb3Se tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Rb(1), two equivalent Rb(2), and one Se(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(2), one Ca(1), and one Se(1) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to one Rb(2), one Ca(1), and one Se(2) atom. In the seventh O site, O(7) is bonded in a linear geometry to two equivalent Se(1) atoms. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to two equivalent Rb(1), one Ca(1), and two equivalent Se(2) atoms. is represented by the CIF file [CIF]
data_Rb4Ca(Se2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.383
_cell_length_b   8.383
_cell_length_c   8.052
_cell_angle_alpha   97.559
_cell_angle_beta   97.559
_cell_angle_gamma   59.048
_symmetry_Int_Tables_number   1
_cell_volume   479.659
_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
  Rb  Rb0  1  0.207  0.535  0.400  1.0
  Rb  Rb1  1  0.465  0.793  0.100  1.0
  Rb  Rb2  1  0.782  0.549  0.559  1.0
  Rb  Rb3  1  0.451  0.218  0.941  1.0
  Ca  Ca4  1  0.913  0.087  0.750  1.0
  Se  Se5  1  0.706  0.107  0.394  1.0
  Se  Se6  1  0.893  0.294  0.106  1.0
  Se  Se7  1  0.312  0.897  0.618  1.0
  Se  Se8  1  0.103  0.688  0.882  1.0
  O  O9  1  0.646  0.270  0.561  1.0
  O  O10  1  0.730  0.354  0.939  1.0
  O  O11  1  0.383  0.775  0.434  1.0
  O  O12  1  0.225  0.617  0.066  1.0
  O  O13  1  0.515  0.112  0.294  1.0
  O  O14  1  0.888  0.485  0.206  1.0
  O  O15  1  0.492  0.902  0.733  1.0
  O  O16  1  0.098  0.508  0.767  1.0
  O  O17  1  0.856  0.906  0.486  1.0
  O  O18  1  0.094  0.144  0.014  1.0
  O  O19  1  0.124  0.113  0.597  1.0
  O  O20  1  0.887  0.876  0.903  1.0
  O  O21  1  0.818  0.182  0.250  1.0
  O  O22  1  0.213  0.787  0.750  1.0
[/CIF]
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