The material described by Rb2MgO2 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second Rb site, Rb(2) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted RbO4 trigonal pyramids that share  a cornercorner with one Mg(2)O4 tetrahedra, corners with two equivalent Rb(2)O4 trigonal pyramids, and  an edgeedge with one Mg(2)O4 tetrahedra. In the third Rb site, Rb(3) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(4) atoms. In the fourth Rb site, Rb(4) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), and two equivalent O(2) atoms. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted trigonal planar geometry to one O(1), one O(3), and one O(4) atom. In the second Mg site, Mg(2) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form distorted MgO4 tetrahedra that share  a cornercorner with one Rb(2)O4 trigonal pyramid,  an edgeedge with one Mg(2)O4 tetrahedra, and  an edgeedge with one Rb(2)O4 trigonal pyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(3), one Rb(4), two equivalent Rb(2), and one Mg(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), two equivalent Rb(4), and two equivalent Mg(2) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Rb(1), one Rb(2), one Rb(4), one Mg(1), and one Mg(2) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(4), two equivalent Rb(3), one Mg(1), and one Mg(2) atom. is represented by the CIF card [CIF]
data_Rb2MgO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.489
_cell_length_b   9.780
_cell_length_c   16.209
_cell_angle_alpha   61.686
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   905.668
_cell_formula_units_Z   8
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  0.332  0.853  0.971  1.0
  Rb  Rb1  1  0.871  0.921  0.835  1.0
  Rb  Rb2  1  0.084  0.681  0.740  1.0
  Rb  Rb3  1  0.565  0.568  0.879  1.0
  Rb  Rb4  1  0.168  0.853  0.471  1.0
  Rb  Rb5  1  0.629  0.921  0.335  1.0
  Rb  Rb6  1  0.065  0.432  0.621  1.0
  Rb  Rb7  1  0.584  0.319  0.760  1.0
  Rb  Rb8  1  0.416  0.681  0.240  1.0
  Rb  Rb9  1  0.935  0.568  0.379  1.0
  Rb  Rb10  1  0.371  0.079  0.665  1.0
  Rb  Rb11  1  0.832  0.147  0.529  1.0
  Rb  Rb12  1  0.435  0.432  0.121  1.0
  Rb  Rb13  1  0.916  0.319  0.260  1.0
  Rb  Rb14  1  0.129  0.079  0.165  1.0
  Rb  Rb15  1  0.668  0.147  0.029  1.0
  Mg  Mg16  1  0.629  0.757  0.627  1.0
  Mg  Mg17  1  0.050  0.412  0.960  1.0
  Mg  Mg18  1  0.550  0.588  0.540  1.0
  Mg  Mg19  1  0.129  0.243  0.873  1.0
  Mg  Mg20  1  0.871  0.757  0.127  1.0
  Mg  Mg21  1  0.450  0.412  0.460  1.0
  Mg  Mg22  1  0.950  0.588  0.040  1.0
  Mg  Mg23  1  0.371  0.243  0.373  1.0
  O  O24  1  0.696  0.862  0.697  1.0
  O  O25  1  0.128  0.629  0.930  1.0
  O  O26  1  0.775  0.740  0.527  1.0
  O  O27  1  0.402  0.617  0.642  1.0
  O  O28  1  0.902  0.383  0.858  1.0
  O  O29  1  0.275  0.260  0.973  1.0
  O  O30  1  0.804  0.862  0.197  1.0
  O  O31  1  0.372  0.629  0.430  1.0
  O  O32  1  0.628  0.371  0.570  1.0
  O  O33  1  0.196  0.138  0.803  1.0
  O  O34  1  0.725  0.740  0.027  1.0
  O  O35  1  0.098  0.617  0.142  1.0
  O  O36  1  0.598  0.383  0.358  1.0
  O  O37  1  0.225  0.260  0.473  1.0
  O  O38  1  0.872  0.371  0.070  1.0
  O  O39  1  0.304  0.138  0.303  1.0
[/CIF]
.
The material described by Rb2MgO2 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second Rb site, Rb(2) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted RbO4 trigonal pyramids that share  a cornercorner with one Mg(2)O4 tetrahedra, corners with two equivalent Rb(2)O4 trigonal pyramids, and  an edgeedge with one Mg(2)O4 tetrahedra. In the third Rb site, Rb(3) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(4) atoms. In the fourth Rb site, Rb(4) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), and two equivalent O(2) atoms. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted trigonal planar geometry to one O(1), one O(3), and one O(4) atom. In the second Mg site, Mg(2) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form distorted MgO4 tetrahedra that share  a cornercorner with one Rb(2)O4 trigonal pyramid,  an edgeedge with one Mg(2)O4 tetrahedra, and  an edgeedge with one Rb(2)O4 trigonal pyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(3), one Rb(4), two equivalent Rb(2), and one Mg(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), two equivalent Rb(4), and two equivalent Mg(2) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Rb(1), one Rb(2), one Rb(4), one Mg(1), and one Mg(2) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Rb(1), one Rb(4), two equivalent Rb(3), one Mg(1), and one Mg(2) atom. is represented by the CIF card [CIF]
data_Rb2MgO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.489
_cell_length_b   9.780
_cell_length_c   16.209
_cell_angle_alpha   61.686
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   905.668
_cell_formula_units_Z   8
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  0.332  0.853  0.971  1.0
  Rb  Rb1  1  0.871  0.921  0.835  1.0
  Rb  Rb2  1  0.084  0.681  0.740  1.0
  Rb  Rb3  1  0.565  0.568  0.879  1.0
  Rb  Rb4  1  0.168  0.853  0.471  1.0
  Rb  Rb5  1  0.629  0.921  0.335  1.0
  Rb  Rb6  1  0.065  0.432  0.621  1.0
  Rb  Rb7  1  0.584  0.319  0.760  1.0
  Rb  Rb8  1  0.416  0.681  0.240  1.0
  Rb  Rb9  1  0.935  0.568  0.379  1.0
  Rb  Rb10  1  0.371  0.079  0.665  1.0
  Rb  Rb11  1  0.832  0.147  0.529  1.0
  Rb  Rb12  1  0.435  0.432  0.121  1.0
  Rb  Rb13  1  0.916  0.319  0.260  1.0
  Rb  Rb14  1  0.129  0.079  0.165  1.0
  Rb  Rb15  1  0.668  0.147  0.029  1.0
  Mg  Mg16  1  0.629  0.757  0.627  1.0
  Mg  Mg17  1  0.050  0.412  0.960  1.0
  Mg  Mg18  1  0.550  0.588  0.540  1.0
  Mg  Mg19  1  0.129  0.243  0.873  1.0
  Mg  Mg20  1  0.871  0.757  0.127  1.0
  Mg  Mg21  1  0.450  0.412  0.460  1.0
  Mg  Mg22  1  0.950  0.588  0.040  1.0
  Mg  Mg23  1  0.371  0.243  0.373  1.0
  O  O24  1  0.696  0.862  0.697  1.0
  O  O25  1  0.128  0.629  0.930  1.0
  O  O26  1  0.775  0.740  0.527  1.0
  O  O27  1  0.402  0.617  0.642  1.0
  O  O28  1  0.902  0.383  0.858  1.0
  O  O29  1  0.275  0.260  0.973  1.0
  O  O30  1  0.804  0.862  0.197  1.0
  O  O31  1  0.372  0.629  0.430  1.0
  O  O32  1  0.628  0.371  0.570  1.0
  O  O33  1  0.196  0.138  0.803  1.0
  O  O34  1  0.725  0.740  0.027  1.0
  O  O35  1  0.098  0.617  0.142  1.0
  O  O36  1  0.598  0.383  0.358  1.0
  O  O37  1  0.225  0.260  0.473  1.0
  O  O38  1  0.872  0.371  0.070  1.0
  O  O39  1  0.304  0.138  0.303  1.0
[/CIF]
.