The structure described by Mg(AlH4)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one H(1), one H(2), one H(3), one H(6), one H(7), and one H(8) atom to form MgH6 octahedra that share corners with three equivalent Al(1)H5 trigonal bipyramids and corners with three equivalent Al(2)H5 trigonal bipyramids. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one H(1), one H(2), one H(3), one H(4), and one H(5) atom to form distorted AlH5 trigonal bipyramids that share corners with three equivalent Mg(1)H6 octahedra and  an edgeedge with one Al(2)H5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 44-47°. In the second Al site, Al(2) is bonded to one H(4), one H(5), one H(6), one H(7), and one H(8) atom to form distorted AlH5 trigonal bipyramids that share corners with three equivalent Mg(1)H6 octahedra and  an edgeedge with one Al(1)H5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 45-48°. There are eight 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 distorted bent 120 degrees geometry to one Mg(1) and one Al(1) atom. In the third H site, H(3) is bonded in a bent 120 degrees geometry to one Mg(1) and one Al(1) atom. In the fourth H site, H(4) is bonded in a water-like geometry to one Al(1) and one Al(2) atom. In the fifth H site, H(5) is bonded in a water-like geometry to one Al(1) and one Al(2) atom. In the sixth H site, H(6) is bonded in a bent 120 degrees geometry to one Mg(1) and one Al(2) atom. In the seventh H site, H(7) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Al(2) atom. In the eighth H site, H(8) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one Al(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg(AlH4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.796
_cell_length_b   4.907
_cell_length_c   6.465
_cell_angle_alpha   94.778
_cell_angle_beta   98.921
_cell_angle_gamma   123.169
_symmetry_Int_Tables_number   1
_cell_volume   123.204
_cell_formula_units_Z   1
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  0.993  0.993  0.005  1.0
  Al  Al1  1  0.787  0.418  0.296  1.0
  Al  Al2  1  0.199  0.568  0.713  1.0
  H  H3  1  0.421  0.358  0.164  1.0
  H  H4  1  0.748  0.079  0.192  1.0
  H  H5  1  0.058  0.746  0.207  1.0
  H  H6  1  0.246  0.534  0.470  1.0
  H  H7  1  0.742  0.454  0.540  1.0
  H  H8  1  0.927  0.237  0.800  1.0
  H  H9  1  0.238  0.906  0.818  1.0
  H  H10  1  0.563  0.626  0.846  1.0
[/CIF]
.
The structure described by Mg(AlH4)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one H(1), one H(2), one H(3), one H(6), one H(7), and one H(8) atom to form MgH6 octahedra that share corners with three equivalent Al(1)H5 trigonal bipyramids and corners with three equivalent Al(2)H5 trigonal bipyramids. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one H(1), one H(2), one H(3), one H(4), and one H(5) atom to form distorted AlH5 trigonal bipyramids that share corners with three equivalent Mg(1)H6 octahedra and  an edgeedge with one Al(2)H5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 44-47°. In the second Al site, Al(2) is bonded to one H(4), one H(5), one H(6), one H(7), and one H(8) atom to form distorted AlH5 trigonal bipyramids that share corners with three equivalent Mg(1)H6 octahedra and  an edgeedge with one Al(1)H5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 45-48°. There are eight 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 distorted bent 120 degrees geometry to one Mg(1) and one Al(1) atom. In the third H site, H(3) is bonded in a bent 120 degrees geometry to one Mg(1) and one Al(1) atom. In the fourth H site, H(4) is bonded in a water-like geometry to one Al(1) and one Al(2) atom. In the fifth H site, H(5) is bonded in a water-like geometry to one Al(1) and one Al(2) atom. In the sixth H site, H(6) is bonded in a bent 120 degrees geometry to one Mg(1) and one Al(2) atom. In the seventh H site, H(7) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Al(2) atom. In the eighth H site, H(8) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one Al(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg(AlH4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.796
_cell_length_b   4.907
_cell_length_c   6.465
_cell_angle_alpha   94.778
_cell_angle_beta   98.921
_cell_angle_gamma   123.169
_symmetry_Int_Tables_number   1
_cell_volume   123.204
_cell_formula_units_Z   1
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  0.993  0.993  0.005  1.0
  Al  Al1  1  0.787  0.418  0.296  1.0
  Al  Al2  1  0.199  0.568  0.713  1.0
  H  H3  1  0.421  0.358  0.164  1.0
  H  H4  1  0.748  0.079  0.192  1.0
  H  H5  1  0.058  0.746  0.207  1.0
  H  H6  1  0.246  0.534  0.470  1.0
  H  H7  1  0.742  0.454  0.540  1.0
  H  H8  1  0.927  0.237  0.800  1.0
  H  H9  1  0.238  0.906  0.818  1.0
  H  H10  1  0.563  0.626  0.846  1.0
[/CIF]
.