The compound described by MgAlH5 crystallizes in the orthorhombic C222_1 space group. Mg(1) is bonded to two equivalent H(1) and four equivalent H(2) atoms to form MgH6 octahedra that share corners with four equivalent Mg(1)H6 octahedra, corners with four equivalent Al(1)H6 octahedra, and  an edgeedge with one Al(1)H6 octahedra. The corner-sharing octahedral tilt angles range from 41-57°. Al(1) is bonded to two equivalent H(1), two equivalent H(2), and two equivalent H(3) atoms to form AlH6 octahedra that share corners with two equivalent Al(1)H6 octahedra, corners with four equivalent Mg(1)H6 octahedra, and  an edgeedge with one Mg(1)H6 octahedra. The corner-sharing octahedral tilt angles range from 41-57°. There are three inequivalent H sites. In the first H site, H(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one Al(1) atom. In the second H site, H(2) is bonded in a trigonal planar geometry to two equivalent Mg(1) and one Al(1) atom. In the third H site, H(3) is bonded in a bent 120 degrees geometry to two equivalent Al(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgAlH5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.885
_cell_length_b   6.885
_cell_length_c   4.273
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   141.785
_symmetry_Int_Tables_number   1
_cell_volume   125.321
_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
  Mg  Mg0  1  0.679  0.321  0.750  1.0
  Mg  Mg1  1  0.321  0.679  0.250  1.0
  Al  Al2  1  0.091  0.909  0.250  1.0
  Al  Al3  1  0.909  0.091  0.750  1.0
  H  H4  1  0.217  0.401  0.530  1.0
  H  H5  1  0.599  0.783  0.970  1.0
  H  H6  1  0.783  0.599  0.030  1.0
  H  H7  1  0.401  0.217  0.470  1.0
  H  H8  1  0.961  0.350  0.971  1.0
  H  H9  1  0.650  0.039  0.529  1.0
  H  H10  1  0.039  0.650  0.471  1.0
  H  H11  1  0.350  0.961  0.029  1.0
  H  H12  1  0.164  0.164  0.000  1.0
  H  H13  1  0.836  0.836  0.500  1.0
[/CIF]
.
The compound described by MgAlH5 crystallizes in the orthorhombic C222_1 space group. Mg(1) is bonded to two equivalent H(1) and four equivalent H(2) atoms to form MgH6 octahedra that share corners with four equivalent Mg(1)H6 octahedra, corners with four equivalent Al(1)H6 octahedra, and  an edgeedge with one Al(1)H6 octahedra. The corner-sharing octahedral tilt angles range from 41-57°. Al(1) is bonded to two equivalent H(1), two equivalent H(2), and two equivalent H(3) atoms to form AlH6 octahedra that share corners with two equivalent Al(1)H6 octahedra, corners with four equivalent Mg(1)H6 octahedra, and  an edgeedge with one Mg(1)H6 octahedra. The corner-sharing octahedral tilt angles range from 41-57°. There are three inequivalent H sites. In the first H site, H(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one Al(1) atom. In the second H site, H(2) is bonded in a trigonal planar geometry to two equivalent Mg(1) and one Al(1) atom. In the third H site, H(3) is bonded in a bent 120 degrees geometry to two equivalent Al(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgAlH5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.885
_cell_length_b   6.885
_cell_length_c   4.273
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   141.785
_symmetry_Int_Tables_number   1
_cell_volume   125.321
_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
  Mg  Mg0  1  0.679  0.321  0.750  1.0
  Mg  Mg1  1  0.321  0.679  0.250  1.0
  Al  Al2  1  0.091  0.909  0.250  1.0
  Al  Al3  1  0.909  0.091  0.750  1.0
  H  H4  1  0.217  0.401  0.530  1.0
  H  H5  1  0.599  0.783  0.970  1.0
  H  H6  1  0.783  0.599  0.030  1.0
  H  H7  1  0.401  0.217  0.470  1.0
  H  H8  1  0.961  0.350  0.971  1.0
  H  H9  1  0.650  0.039  0.529  1.0
  H  H10  1  0.039  0.650  0.471  1.0
  H  H11  1  0.350  0.961  0.029  1.0
  H  H12  1  0.164  0.164  0.000  1.0
  H  H13  1  0.836  0.836  0.500  1.0
[/CIF]
.