The crystal structure described by Rb4Mg(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 6-coordinate geometry to one O(4), one O(5), 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. Mg(1) is bonded in a 5-coordinate geometry to one O(8), two equivalent O(1), and two equivalent O(6) atoms. 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 corner-sharing SeO4 tetrahedra. 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 corner-sharing SeO4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Rb(2), one Mg(1), and one Se(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(2) atom. 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 distorted single-bond 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 3-coordinate geometry to one Rb(1), one Rb(2), and one Se(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Rb(2), one Mg(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 one Mg(1) and two equivalent Se(2) atoms. is represented by the CIF file [CIF]
data_Rb4Mg(Se2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.256
_cell_length_b   8.256
_cell_length_c   8.127
_cell_angle_alpha   95.515
_cell_angle_beta   95.515
_cell_angle_gamma   59.423
_symmetry_Int_Tables_number   1
_cell_volume   473.999
_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  0.173  0.525  0.347  1.0
  Rb  Rb1  1  0.475  0.827  0.153  1.0
  Rb  Rb2  1  0.780  0.524  0.554  1.0
  Rb  Rb3  1  0.476  0.220  0.946  1.0
  Mg  Mg4  1  0.891  0.109  0.750  1.0
  Se  Se5  1  0.719  0.069  0.392  1.0
  Se  Se6  1  0.931  0.281  0.108  1.0
  Se  Se7  1  0.298  0.910  0.639  1.0
  Se  Se8  1  0.090  0.702  0.861  1.0
  O  O9  1  0.687  0.201  0.582  1.0
  O  O10  1  0.799  0.313  0.918  1.0
  O  O11  1  0.360  0.767  0.472  1.0
  O  O12  1  0.233  0.640  0.028  1.0
  O  O13  1  0.497  0.150  0.306  1.0
  O  O14  1  0.850  0.503  0.194  1.0
  O  O15  1  0.476  0.879  0.767  1.0
  O  O16  1  0.121  0.524  0.733  1.0
  O  O17  1  0.802  0.845  0.447  1.0
  O  O18  1  0.155  0.198  0.053  1.0
  O  O19  1  0.121  0.129  0.617  1.0
  O  O20  1  0.871  0.879  0.883  1.0
  O  O21  1  0.854  0.146  0.250  1.0
  O  O22  1  0.143  0.857  0.750  1.0
[/CIF]
.
The crystal structure described by Rb4Mg(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 6-coordinate geometry to one O(4), one O(5), 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. Mg(1) is bonded in a 5-coordinate geometry to one O(8), two equivalent O(1), and two equivalent O(6) atoms. 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 corner-sharing SeO4 tetrahedra. 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 corner-sharing SeO4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Rb(2), one Mg(1), and one Se(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Se(2) atom. 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 distorted single-bond 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 3-coordinate geometry to one Rb(1), one Rb(2), and one Se(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Rb(2), one Mg(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 one Mg(1) and two equivalent Se(2) atoms. is represented by the CIF file [CIF]
data_Rb4Mg(Se2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.256
_cell_length_b   8.256
_cell_length_c   8.127
_cell_angle_alpha   95.515
_cell_angle_beta   95.515
_cell_angle_gamma   59.423
_symmetry_Int_Tables_number   1
_cell_volume   473.999
_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  0.173  0.525  0.347  1.0
  Rb  Rb1  1  0.475  0.827  0.153  1.0
  Rb  Rb2  1  0.780  0.524  0.554  1.0
  Rb  Rb3  1  0.476  0.220  0.946  1.0
  Mg  Mg4  1  0.891  0.109  0.750  1.0
  Se  Se5  1  0.719  0.069  0.392  1.0
  Se  Se6  1  0.931  0.281  0.108  1.0
  Se  Se7  1  0.298  0.910  0.639  1.0
  Se  Se8  1  0.090  0.702  0.861  1.0
  O  O9  1  0.687  0.201  0.582  1.0
  O  O10  1  0.799  0.313  0.918  1.0
  O  O11  1  0.360  0.767  0.472  1.0
  O  O12  1  0.233  0.640  0.028  1.0
  O  O13  1  0.497  0.150  0.306  1.0
  O  O14  1  0.850  0.503  0.194  1.0
  O  O15  1  0.476  0.879  0.767  1.0
  O  O16  1  0.121  0.524  0.733  1.0
  O  O17  1  0.802  0.845  0.447  1.0
  O  O18  1  0.155  0.198  0.053  1.0
  O  O19  1  0.121  0.129  0.617  1.0
  O  O20  1  0.871  0.879  0.883  1.0
  O  O21  1  0.854  0.146  0.250  1.0
  O  O22  1  0.143  0.857  0.750  1.0
[/CIF]
.