The crystal structure described by Rb4Ca(Se2O7)2 crystallizes in the triclinic P1 space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to one O(12), one O(3), one O(4), one O(5), one O(6), one O(8), and one O(9) atom. In the second Rb site, Rb(2) is bonded in a 5-coordinate geometry to one O(10), one O(12), one O(2), one O(3), and one O(4) atom. In the third Rb site, Rb(3) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(2), one O(3), one O(6), one O(7), and one O(8) atom. In the fourth Rb site, Rb(4) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(12), one O(13), one O(14), one O(2), one O(4), and one O(5) atom. Ca(1) is bonded in a 5-coordinate geometry to one O(1), one O(11), one O(5), one O(7), and one O(8) atom. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one O(1), one O(13), one O(5), and one O(9) atom. In the second Se site, Se(2) is bonded in a tetrahedral geometry to one O(10), one O(13), one O(2), and one O(6) atom. In the third Se site, Se(3) is bonded to one O(11), one O(14), one O(3), and one O(7) atom to form distorted corner-sharing SeO4 tetrahedra. In the fourth Se site, Se(4) is bonded to one O(12), one O(14), one O(4), and one O(8) atom to form corner-sharing SeO4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Rb(3), one Rb(4), one Ca(1), and one Se(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Rb(2), one Rb(3), one Rb(4), and one Se(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), and one Se(3) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), one Rb(4), and one Se(4) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Rb(1), one Rb(4), one Ca(1), and one Se(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(3), and one Se(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Rb(3), one Ca(1), and one Se(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(3), one Ca(1), and one Se(4) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one Rb(1) and one Se(1) atom. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one Rb(2), one Rb(4), and one Se(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Rb(3), one Ca(1), and one Se(3) atom. In the twelfth O site, O(12) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), one Rb(4), and one Se(4) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Rb(4), one Se(1), and one Se(2) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Rb(4), one Se(3), and one Se(4) atom. is represented by the CIF file [CIF]
data_Rb4Ca(Se2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.099
_cell_length_b   8.479
_cell_length_c   8.103
_cell_angle_alpha   92.389
_cell_angle_beta   86.494
_cell_angle_gamma   58.192
_symmetry_Int_Tables_number   1
_cell_volume   470.207
_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  0.149  0.590  0.283  1.0
  Rb  Rb1  1  0.497  0.789  0.123  1.0
  Rb  Rb2  1  0.760  0.496  0.648  1.0
  Rb  Rb3  1  0.637  0.148  0.965  1.0
  Ca  Ca4  1  0.339  0.225  0.601  1.0
  Se  Se5  1  0.715  0.127  0.416  1.0
  Se  Se6  1  0.951  0.293  0.129  1.0
  Se  Se7  1  0.275  0.902  0.620  1.0
  Se  Se8  1  0.084  0.669  0.846  1.0
  O  O9  1  0.631  0.220  0.620  1.0
  O  O10  1  0.781  0.396  0.996  1.0
  O  O11  1  0.381  0.731  0.464  1.0
  O  O12  1  0.295  0.573  0.932  1.0
  O  O13  1  0.492  0.217  0.334  1.0
  O  O14  1  0.896  0.441  0.295  1.0
  O  O15  1  0.456  0.923  0.702  1.0
  O  O16  1  0.108  0.523  0.684  1.0
  O  O17  1  0.810  0.899  0.409  1.0
  O  O18  1  0.178  0.204  0.042  1.0
  O  O19  1  0.139  0.113  0.541  1.0
  O  O20  1  0.897  0.715  0.980  1.0
  O  O21  1  0.940  0.104  0.188  1.0
  O  O22  1  0.024  0.876  0.775  1.0
[/CIF]
.
The crystal structure described by Rb4Ca(Se2O7)2 crystallizes in the triclinic P1 space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to one O(12), one O(3), one O(4), one O(5), one O(6), one O(8), and one O(9) atom. In the second Rb site, Rb(2) is bonded in a 5-coordinate geometry to one O(10), one O(12), one O(2), one O(3), and one O(4) atom. In the third Rb site, Rb(3) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(2), one O(3), one O(6), one O(7), and one O(8) atom. In the fourth Rb site, Rb(4) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(12), one O(13), one O(14), one O(2), one O(4), and one O(5) atom. Ca(1) is bonded in a 5-coordinate geometry to one O(1), one O(11), one O(5), one O(7), and one O(8) atom. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one O(1), one O(13), one O(5), and one O(9) atom. In the second Se site, Se(2) is bonded in a tetrahedral geometry to one O(10), one O(13), one O(2), and one O(6) atom. In the third Se site, Se(3) is bonded to one O(11), one O(14), one O(3), and one O(7) atom to form distorted corner-sharing SeO4 tetrahedra. In the fourth Se site, Se(4) is bonded to one O(12), one O(14), one O(4), and one O(8) atom to form corner-sharing SeO4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Rb(3), one Rb(4), one Ca(1), and one Se(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Rb(2), one Rb(3), one Rb(4), and one Se(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), and one Se(3) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), one Rb(4), and one Se(4) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Rb(1), one Rb(4), one Ca(1), and one Se(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(3), and one Se(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Rb(3), one Ca(1), and one Se(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Rb(1), one Rb(3), one Ca(1), and one Se(4) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one Rb(1) and one Se(1) atom. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one Rb(2), one Rb(4), and one Se(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Rb(3), one Ca(1), and one Se(3) atom. In the twelfth O site, O(12) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), one Rb(4), and one Se(4) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Rb(4), one Se(1), and one Se(2) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Rb(4), one Se(3), and one Se(4) atom. is represented by the CIF file [CIF]
data_Rb4Ca(Se2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.099
_cell_length_b   8.479
_cell_length_c   8.103
_cell_angle_alpha   92.389
_cell_angle_beta   86.494
_cell_angle_gamma   58.192
_symmetry_Int_Tables_number   1
_cell_volume   470.207
_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  0.149  0.590  0.283  1.0
  Rb  Rb1  1  0.497  0.789  0.123  1.0
  Rb  Rb2  1  0.760  0.496  0.648  1.0
  Rb  Rb3  1  0.637  0.148  0.965  1.0
  Ca  Ca4  1  0.339  0.225  0.601  1.0
  Se  Se5  1  0.715  0.127  0.416  1.0
  Se  Se6  1  0.951  0.293  0.129  1.0
  Se  Se7  1  0.275  0.902  0.620  1.0
  Se  Se8  1  0.084  0.669  0.846  1.0
  O  O9  1  0.631  0.220  0.620  1.0
  O  O10  1  0.781  0.396  0.996  1.0
  O  O11  1  0.381  0.731  0.464  1.0
  O  O12  1  0.295  0.573  0.932  1.0
  O  O13  1  0.492  0.217  0.334  1.0
  O  O14  1  0.896  0.441  0.295  1.0
  O  O15  1  0.456  0.923  0.702  1.0
  O  O16  1  0.108  0.523  0.684  1.0
  O  O17  1  0.810  0.899  0.409  1.0
  O  O18  1  0.178  0.204  0.042  1.0
  O  O19  1  0.139  0.113  0.541  1.0
  O  O20  1  0.897  0.715  0.980  1.0
  O  O21  1  0.940  0.104  0.188  1.0
  O  O22  1  0.024  0.876  0.775  1.0
[/CIF]
.