The material described by NaMg2HSe2O7 crystallizes in the orthorhombic Pnma space group. Na(1) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form NaO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with three equivalent Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 63-79°. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Na(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Mg(2)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(1), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with three equivalent Na(1)O4 tetrahedra and edges with two equivalent Mg(1)O6 octahedra. H(1) is bonded in a single-bond geometry to one O(5) atom. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(1) and two equivalent O(2) atoms. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(4) and two equivalent O(3) atoms. There are five inequivalent O sites. In the first O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Mg(2), and one Se(2) atom. In the second O site, O(4) is bonded to one Na(1), two equivalent Mg(1), and one Se(2) atom to form distorted ONaMg2Se tetrahedra that share corners with two equivalent O(5)Mg3H tetrahedra, corners with two equivalent O(4)NaMg2Se tetrahedra, and  an edgeedge with one O(5)Mg3H tetrahedra. In the third O site, O(5) is bonded to one Mg(2), two equivalent Mg(1), and one H(1) atom to form distorted OMg3H tetrahedra that share corners with two equivalent O(5)Mg3H tetrahedra, corners with two equivalent O(4)NaMg2Se tetrahedra, and  an edgeedge with one O(4)NaMg2Se tetrahedra. In the fourth O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Mg(2), and one Se(1) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one Se(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_NaMg2HSe2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.178
_cell_length_b   8.378
_cell_length_c   13.533
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   700.421
_cell_formula_units_Z   4
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
  Na  Na0  1  0.750  0.869  0.751  1.0
  Na  Na1  1  0.750  0.631  0.251  1.0
  Na  Na2  1  0.250  0.131  0.249  1.0
  Na  Na3  1  0.250  0.369  0.749  1.0
  Mg  Mg4  1  0.000  0.500  0.000  1.0
  Mg  Mg5  1  0.500  0.000  0.500  1.0
  Mg  Mg6  1  0.500  0.500  0.000  1.0
  Mg  Mg7  1  0.000  0.000  0.500  1.0
  Mg  Mg8  1  0.750  0.214  0.888  1.0
  Mg  Mg9  1  0.750  0.286  0.388  1.0
  Mg  Mg10  1  0.250  0.786  0.112  1.0
  Mg  Mg11  1  0.250  0.714  0.612  1.0
  H  H12  1  0.750  0.528  0.845  1.0
  H  H13  1  0.750  0.972  0.345  1.0
  H  H14  1  0.250  0.472  0.155  1.0
  H  H15  1  0.250  0.028  0.655  1.0
  Se  Se16  1  0.250  0.120  0.973  1.0
  Se  Se17  1  0.250  0.380  0.473  1.0
  Se  Se18  1  0.750  0.880  0.027  1.0
  Se  Se19  1  0.750  0.620  0.527  1.0
  Se  Se20  1  0.750  0.226  0.673  1.0
  Se  Se21  1  0.750  0.274  0.173  1.0
  Se  Se22  1  0.250  0.774  0.327  1.0
  Se  Se23  1  0.250  0.726  0.827  1.0
  O  O24  1  0.250  0.031  0.087  1.0
  O  O25  1  0.250  0.469  0.587  1.0
  O  O26  1  0.750  0.969  0.913  1.0
  O  O27  1  0.750  0.531  0.413  1.0
  O  O28  1  0.031  0.249  0.981  1.0
  O  O29  1  0.469  0.251  0.481  1.0
  O  O30  1  0.531  0.751  0.019  1.0
  O  O31  1  0.969  0.749  0.519  1.0
  O  O32  1  0.969  0.751  0.019  1.0
  O  O33  1  0.531  0.749  0.519  1.0
  O  O34  1  0.469  0.249  0.981  1.0
  O  O35  1  0.031  0.251  0.481  1.0
  O  O36  1  0.956  0.198  0.757  1.0
  O  O37  1  0.544  0.302  0.257  1.0
  O  O38  1  0.456  0.802  0.243  1.0
  O  O39  1  0.044  0.698  0.743  1.0
  O  O40  1  0.044  0.802  0.243  1.0
  O  O41  1  0.456  0.698  0.743  1.0
  O  O42  1  0.544  0.198  0.757  1.0
  O  O43  1  0.956  0.302  0.257  1.0
  O  O44  1  0.750  0.043  0.610  1.0
  O  O45  1  0.750  0.457  0.110  1.0
  O  O46  1  0.250  0.957  0.390  1.0
  O  O47  1  0.250  0.543  0.890  1.0
  O  O48  1  0.750  0.463  0.904  1.0
  O  O49  1  0.750  0.037  0.404  1.0
  O  O50  1  0.250  0.537  0.096  1.0
  O  O51  1  0.250  0.963  0.596  1.0
[/CIF]
.
The material described by NaMg2HSe2O7 crystallizes in the orthorhombic Pnma space group. Na(1) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form NaO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with three equivalent Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 63-79°. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Na(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Mg(2)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(1), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with three equivalent Na(1)O4 tetrahedra and edges with two equivalent Mg(1)O6 octahedra. H(1) is bonded in a single-bond geometry to one O(5) atom. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(1) and two equivalent O(2) atoms. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(4) and two equivalent O(3) atoms. There are five inequivalent O sites. In the first O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Mg(2), and one Se(2) atom. In the second O site, O(4) is bonded to one Na(1), two equivalent Mg(1), and one Se(2) atom to form distorted ONaMg2Se tetrahedra that share corners with two equivalent O(5)Mg3H tetrahedra, corners with two equivalent O(4)NaMg2Se tetrahedra, and  an edgeedge with one O(5)Mg3H tetrahedra. In the third O site, O(5) is bonded to one Mg(2), two equivalent Mg(1), and one H(1) atom to form distorted OMg3H tetrahedra that share corners with two equivalent O(5)Mg3H tetrahedra, corners with two equivalent O(4)NaMg2Se tetrahedra, and  an edgeedge with one O(4)NaMg2Se tetrahedra. In the fourth O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Mg(2), and one Se(1) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one Se(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_NaMg2HSe2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.178
_cell_length_b   8.378
_cell_length_c   13.533
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   700.421
_cell_formula_units_Z   4
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
  Na  Na0  1  0.750  0.869  0.751  1.0
  Na  Na1  1  0.750  0.631  0.251  1.0
  Na  Na2  1  0.250  0.131  0.249  1.0
  Na  Na3  1  0.250  0.369  0.749  1.0
  Mg  Mg4  1  0.000  0.500  0.000  1.0
  Mg  Mg5  1  0.500  0.000  0.500  1.0
  Mg  Mg6  1  0.500  0.500  0.000  1.0
  Mg  Mg7  1  0.000  0.000  0.500  1.0
  Mg  Mg8  1  0.750  0.214  0.888  1.0
  Mg  Mg9  1  0.750  0.286  0.388  1.0
  Mg  Mg10  1  0.250  0.786  0.112  1.0
  Mg  Mg11  1  0.250  0.714  0.612  1.0
  H  H12  1  0.750  0.528  0.845  1.0
  H  H13  1  0.750  0.972  0.345  1.0
  H  H14  1  0.250  0.472  0.155  1.0
  H  H15  1  0.250  0.028  0.655  1.0
  Se  Se16  1  0.250  0.120  0.973  1.0
  Se  Se17  1  0.250  0.380  0.473  1.0
  Se  Se18  1  0.750  0.880  0.027  1.0
  Se  Se19  1  0.750  0.620  0.527  1.0
  Se  Se20  1  0.750  0.226  0.673  1.0
  Se  Se21  1  0.750  0.274  0.173  1.0
  Se  Se22  1  0.250  0.774  0.327  1.0
  Se  Se23  1  0.250  0.726  0.827  1.0
  O  O24  1  0.250  0.031  0.087  1.0
  O  O25  1  0.250  0.469  0.587  1.0
  O  O26  1  0.750  0.969  0.913  1.0
  O  O27  1  0.750  0.531  0.413  1.0
  O  O28  1  0.031  0.249  0.981  1.0
  O  O29  1  0.469  0.251  0.481  1.0
  O  O30  1  0.531  0.751  0.019  1.0
  O  O31  1  0.969  0.749  0.519  1.0
  O  O32  1  0.969  0.751  0.019  1.0
  O  O33  1  0.531  0.749  0.519  1.0
  O  O34  1  0.469  0.249  0.981  1.0
  O  O35  1  0.031  0.251  0.481  1.0
  O  O36  1  0.956  0.198  0.757  1.0
  O  O37  1  0.544  0.302  0.257  1.0
  O  O38  1  0.456  0.802  0.243  1.0
  O  O39  1  0.044  0.698  0.743  1.0
  O  O40  1  0.044  0.802  0.243  1.0
  O  O41  1  0.456  0.698  0.743  1.0
  O  O42  1  0.544  0.198  0.757  1.0
  O  O43  1  0.956  0.302  0.257  1.0
  O  O44  1  0.750  0.043  0.610  1.0
  O  O45  1  0.750  0.457  0.110  1.0
  O  O46  1  0.250  0.957  0.390  1.0
  O  O47  1  0.250  0.543  0.890  1.0
  O  O48  1  0.750  0.463  0.904  1.0
  O  O49  1  0.750  0.037  0.404  1.0
  O  O50  1  0.250  0.537  0.096  1.0
  O  O51  1  0.250  0.963  0.596  1.0
[/CIF]
.