The material described by Cs2MgO2 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Cs sites. In the first Cs site, Cs(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 Cs site, Cs(2) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted CsO4 trigonal pyramids that share  a cornercorner with one Mg(2)O4 tetrahedra, corners with two equivalent Cs(2)O4 trigonal pyramids, and  an edgeedge with one Mg(2)O4 tetrahedra. In the third Cs site, Cs(3) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(4) atoms. In the fourth Cs site, Cs(4) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) 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 Cs(2)O4 trigonal pyramid,  an edgeedge with one Mg(2)O4 tetrahedra, and  an edgeedge with one Cs(2)O4 trigonal pyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(3), one Cs(4), two equivalent Cs(2), and one Mg(1) atom. In the second O site, O(2) is bonded in a distorted L-shaped geometry to one Cs(1), one Cs(2), one Cs(3), two equivalent Cs(4), and two equivalent Mg(2) atoms. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Cs(1), one Cs(2), two equivalent Cs(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 Cs(1), one Cs(4), two equivalent Cs(3), one Mg(1), and one Mg(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Cs2MgO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.784
_cell_length_b   10.069
_cell_length_c   16.713
_cell_angle_alpha   63.103
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1018.118
_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
  Cs  Cs0  1  0.335  0.852  0.973  1.0
  Cs  Cs1  1  0.866  0.925  0.836  1.0
  Cs  Cs2  1  0.086  0.679  0.741  1.0
  Cs  Cs3  1  0.570  0.572  0.878  1.0
  Cs  Cs4  1  0.165  0.852  0.473  1.0
  Cs  Cs5  1  0.634  0.925  0.336  1.0
  Cs  Cs6  1  0.070  0.428  0.622  1.0
  Cs  Cs7  1  0.586  0.321  0.759  1.0
  Cs  Cs8  1  0.414  0.679  0.241  1.0
  Cs  Cs9  1  0.930  0.572  0.378  1.0
  Cs  Cs10  1  0.366  0.075  0.664  1.0
  Cs  Cs11  1  0.835  0.148  0.527  1.0
  Cs  Cs12  1  0.430  0.428  0.122  1.0
  Cs  Cs13  1  0.914  0.321  0.259  1.0
  Cs  Cs14  1  0.134  0.075  0.164  1.0
  Cs  Cs15  1  0.665  0.148  0.027  1.0
  Mg  Mg16  1  0.629  0.754  0.626  1.0
  Mg  Mg17  1  0.050  0.413  0.960  1.0
  Mg  Mg18  1  0.550  0.587  0.540  1.0
  Mg  Mg19  1  0.129  0.246  0.874  1.0
  Mg  Mg20  1  0.871  0.754  0.126  1.0
  Mg  Mg21  1  0.450  0.413  0.460  1.0
  Mg  Mg22  1  0.950  0.587  0.040  1.0
  Mg  Mg23  1  0.371  0.246  0.374  1.0
  O  O24  1  0.690  0.857  0.694  1.0
  O  O25  1  0.119  0.625  0.933  1.0
  O  O26  1  0.767  0.734  0.529  1.0
  O  O27  1  0.412  0.617  0.640  1.0
  O  O28  1  0.912  0.383  0.860  1.0
  O  O29  1  0.267  0.266  0.971  1.0
  O  O30  1  0.810  0.857  0.194  1.0
  O  O31  1  0.381  0.625  0.433  1.0
  O  O32  1  0.619  0.375  0.567  1.0
  O  O33  1  0.190  0.143  0.806  1.0
  O  O34  1  0.733  0.734  0.029  1.0
  O  O35  1  0.088  0.617  0.140  1.0
  O  O36  1  0.588  0.383  0.360  1.0
  O  O37  1  0.233  0.266  0.471  1.0
  O  O38  1  0.881  0.375  0.067  1.0
  O  O39  1  0.310  0.143  0.306  1.0
[/CIF]
.
The material described by Cs2MgO2 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Cs sites. In the first Cs site, Cs(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 Cs site, Cs(2) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted CsO4 trigonal pyramids that share  a cornercorner with one Mg(2)O4 tetrahedra, corners with two equivalent Cs(2)O4 trigonal pyramids, and  an edgeedge with one Mg(2)O4 tetrahedra. In the third Cs site, Cs(3) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(4) atoms. In the fourth Cs site, Cs(4) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) 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 Cs(2)O4 trigonal pyramid,  an edgeedge with one Mg(2)O4 tetrahedra, and  an edgeedge with one Cs(2)O4 trigonal pyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(3), one Cs(4), two equivalent Cs(2), and one Mg(1) atom. In the second O site, O(2) is bonded in a distorted L-shaped geometry to one Cs(1), one Cs(2), one Cs(3), two equivalent Cs(4), and two equivalent Mg(2) atoms. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Cs(1), one Cs(2), two equivalent Cs(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 Cs(1), one Cs(4), two equivalent Cs(3), one Mg(1), and one Mg(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Cs2MgO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.784
_cell_length_b   10.069
_cell_length_c   16.713
_cell_angle_alpha   63.103
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1018.118
_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
  Cs  Cs0  1  0.335  0.852  0.973  1.0
  Cs  Cs1  1  0.866  0.925  0.836  1.0
  Cs  Cs2  1  0.086  0.679  0.741  1.0
  Cs  Cs3  1  0.570  0.572  0.878  1.0
  Cs  Cs4  1  0.165  0.852  0.473  1.0
  Cs  Cs5  1  0.634  0.925  0.336  1.0
  Cs  Cs6  1  0.070  0.428  0.622  1.0
  Cs  Cs7  1  0.586  0.321  0.759  1.0
  Cs  Cs8  1  0.414  0.679  0.241  1.0
  Cs  Cs9  1  0.930  0.572  0.378  1.0
  Cs  Cs10  1  0.366  0.075  0.664  1.0
  Cs  Cs11  1  0.835  0.148  0.527  1.0
  Cs  Cs12  1  0.430  0.428  0.122  1.0
  Cs  Cs13  1  0.914  0.321  0.259  1.0
  Cs  Cs14  1  0.134  0.075  0.164  1.0
  Cs  Cs15  1  0.665  0.148  0.027  1.0
  Mg  Mg16  1  0.629  0.754  0.626  1.0
  Mg  Mg17  1  0.050  0.413  0.960  1.0
  Mg  Mg18  1  0.550  0.587  0.540  1.0
  Mg  Mg19  1  0.129  0.246  0.874  1.0
  Mg  Mg20  1  0.871  0.754  0.126  1.0
  Mg  Mg21  1  0.450  0.413  0.460  1.0
  Mg  Mg22  1  0.950  0.587  0.040  1.0
  Mg  Mg23  1  0.371  0.246  0.374  1.0
  O  O24  1  0.690  0.857  0.694  1.0
  O  O25  1  0.119  0.625  0.933  1.0
  O  O26  1  0.767  0.734  0.529  1.0
  O  O27  1  0.412  0.617  0.640  1.0
  O  O28  1  0.912  0.383  0.860  1.0
  O  O29  1  0.267  0.266  0.971  1.0
  O  O30  1  0.810  0.857  0.194  1.0
  O  O31  1  0.381  0.625  0.433  1.0
  O  O32  1  0.619  0.375  0.567  1.0
  O  O33  1  0.190  0.143  0.806  1.0
  O  O34  1  0.733  0.734  0.029  1.0
  O  O35  1  0.088  0.617  0.140  1.0
  O  O36  1  0.588  0.383  0.360  1.0
  O  O37  1  0.233  0.266  0.471  1.0
  O  O38  1  0.881  0.375  0.067  1.0
  O  O39  1  0.310  0.143  0.306  1.0
[/CIF]
.