The material structure described by Rb2MgH4 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a distorted rectangular see-saw-like geometry to four equivalent H(1) atoms. In the second Rb site, Rb(2) is bonded to two equivalent H(1) and four equivalent H(2) atoms to form distorted RbH6 pentagonal pyramids that share corners with four equivalent Mg(1)H4 tetrahedra, edges with two equivalent Rb(2)H6 pentagonal pyramids, and  an edgeedge with one Mg(1)H4 tetrahedra. Mg(1) is bonded to two equivalent H(1) and two equivalent H(2) atoms to form MgH4 tetrahedra that share corners with four equivalent Rb(2)H6 pentagonal pyramids and  an edgeedge with one Rb(2)H6 pentagonal pyramid. There are two inequivalent H sites. In the first H site, H(1) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Mg(1) atom. In the second H site, H(2) is bonded in a 3-coordinate geometry to two equivalent Rb(2) and one Mg(1) atom. is represented by the CIF card [CIF]
data_Rb2MgH4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.667
_cell_length_b   6.667
_cell_length_c   8.809
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   103.793
_symmetry_Int_Tables_number   1
_cell_volume   380.196
_cell_formula_units_Z   2
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  0.500  0.500  0.500  1.0
  Rb  Rb1  1  0.500  0.500  0.000  1.0
  Rb  Rb2  1  0.910  0.090  0.750  1.0
  Rb  Rb3  1  0.090  0.910  0.250  1.0
  Mg  Mg4  1  0.256  0.744  0.750  1.0
  Mg  Mg5  1  0.744  0.256  0.250  1.0
  H  H6  1  0.546  0.786  0.750  1.0
  H  H7  1  0.786  0.546  0.250  1.0
  H  H8  1  0.838  0.162  0.073  1.0
  H  H9  1  0.838  0.162  0.427  1.0
  H  H10  1  0.162  0.838  0.927  1.0
  H  H11  1  0.162  0.838  0.573  1.0
  H  H12  1  0.214  0.454  0.750  1.0
  H  H13  1  0.454  0.214  0.250  1.0
[/CIF]
.
The material structure described by Rb2MgH4 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a distorted rectangular see-saw-like geometry to four equivalent H(1) atoms. In the second Rb site, Rb(2) is bonded to two equivalent H(1) and four equivalent H(2) atoms to form distorted RbH6 pentagonal pyramids that share corners with four equivalent Mg(1)H4 tetrahedra, edges with two equivalent Rb(2)H6 pentagonal pyramids, and  an edgeedge with one Mg(1)H4 tetrahedra. Mg(1) is bonded to two equivalent H(1) and two equivalent H(2) atoms to form MgH4 tetrahedra that share corners with four equivalent Rb(2)H6 pentagonal pyramids and  an edgeedge with one Rb(2)H6 pentagonal pyramid. There are two inequivalent H sites. In the first H site, H(1) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Rb(1), and one Mg(1) atom. In the second H site, H(2) is bonded in a 3-coordinate geometry to two equivalent Rb(2) and one Mg(1) atom. is represented by the CIF card [CIF]
data_Rb2MgH4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.667
_cell_length_b   6.667
_cell_length_c   8.809
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   103.793
_symmetry_Int_Tables_number   1
_cell_volume   380.196
_cell_formula_units_Z   2
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  0.500  0.500  0.500  1.0
  Rb  Rb1  1  0.500  0.500  0.000  1.0
  Rb  Rb2  1  0.910  0.090  0.750  1.0
  Rb  Rb3  1  0.090  0.910  0.250  1.0
  Mg  Mg4  1  0.256  0.744  0.750  1.0
  Mg  Mg5  1  0.744  0.256  0.250  1.0
  H  H6  1  0.546  0.786  0.750  1.0
  H  H7  1  0.786  0.546  0.250  1.0
  H  H8  1  0.838  0.162  0.073  1.0
  H  H9  1  0.838  0.162  0.427  1.0
  H  H10  1  0.162  0.838  0.927  1.0
  H  H11  1  0.162  0.838  0.573  1.0
  H  H12  1  0.214  0.454  0.750  1.0
  H  H13  1  0.454  0.214  0.250  1.0
[/CIF]
.