The material described by Mg(BH4)2 crystallizes in the tetragonal I4_1/amd space group. The structure consists of a Mg(BH4)2 framework. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to four equivalent H(2) and four equivalent H(3) atoms to form MgH8 hexagonal bipyramids that share edges with four equivalent B(1)H4 tetrahedra. In the second Mg site, Mg(2) is bonded in a body-centered cubic geometry to eight equivalent H(1) atoms. B(1) is bonded to one H(2), one H(3), and two equivalent H(1) atoms to form BH4 tetrahedra that share  an edgeedge with one Mg(1)H8 hexagonal bipyramid. There are three inequivalent H sites. In the first H site, H(2) is bonded in a distorted L-shaped geometry to one Mg(1) and one B(1) atom. In the second H site, H(3) is bonded in an L-shaped geometry to one Mg(1) and one B(1) atom. In the third H site, H(1) is bonded in a distorted L-shaped geometry to one Mg(2) and one B(1) atom. is represented by the CIF card [CIF]
data_Mg(BH4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.971
_cell_length_b   7.971
_cell_length_c   7.971
_cell_angle_alpha   116.580
_cell_angle_beta   116.580
_cell_angle_gamma   96.033
_symmetry_Int_Tables_number   1
_cell_volume   374.445
_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
  Mg  Mg0  1  0.750  0.250  0.500  1.0
  Mg  Mg1  1  0.000  0.000  0.000  1.0
  Mg  Mg2  1  0.500  0.500  0.000  1.0
  Mg  Mg3  1  0.250  0.750  0.500  1.0
  B  B4  1  0.644  0.410  0.765  1.0
  B  B5  1  0.160  0.894  0.265  1.0
  B  B6  1  0.629  0.894  0.735  1.0
  B  B7  1  0.644  0.879  0.235  1.0
  B  B8  1  0.106  0.840  0.735  1.0
  B  B9  1  0.590  0.356  0.235  1.0
  B  B10  1  0.121  0.356  0.765  1.0
  B  B11  1  0.106  0.371  0.265  1.0
  H  H12  1  0.738  0.451  0.958  1.0
  H  H13  1  0.492  0.451  0.713  1.0
  H  H14  1  0.201  0.988  0.458  1.0
  H  H15  1  0.530  0.988  0.787  1.0
  H  H16  1  0.738  0.780  0.287  1.0
  H  H17  1  0.492  0.780  0.042  1.0
  H  H18  1  0.201  0.742  0.213  1.0
  H  H19  1  0.530  0.742  0.542  1.0
  H  H20  1  0.012  0.799  0.542  1.0
  H  H21  1  0.258  0.799  0.787  1.0
  H  H22  1  0.549  0.262  0.042  1.0
  H  H23  1  0.220  0.262  0.713  1.0
  H  H24  1  0.012  0.470  0.213  1.0
  H  H25  1  0.258  0.470  0.458  1.0
  H  H26  1  0.549  0.508  0.287  1.0
  H  H27  1  0.220  0.508  0.958  1.0
  H  H28  1  0.588  0.951  0.363  1.0
  H  H29  1  0.701  0.838  0.863  1.0
  H  H30  1  0.975  0.838  0.137  1.0
  H  H31  1  0.588  0.225  0.637  1.0
  H  H32  1  0.162  0.299  0.137  1.0
  H  H33  1  0.049  0.412  0.637  1.0
  H  H34  1  0.775  0.412  0.363  1.0
  H  H35  1  0.162  0.025  0.863  1.0
  H  H36  1  0.758  0.511  0.753  1.0
  H  H37  1  0.261  0.008  0.253  1.0
  H  H38  1  0.756  0.008  0.747  1.0
  H  H39  1  0.758  0.006  0.247  1.0
  H  H40  1  0.992  0.739  0.747  1.0
  H  H41  1  0.489  0.242  0.247  1.0
  H  H42  1  0.994  0.242  0.753  1.0
  H  H43  1  0.992  0.244  0.253  1.0
[/CIF]
.
The material described by Mg(BH4)2 crystallizes in the tetragonal I4_1/amd space group. The structure consists of a Mg(BH4)2 framework. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to four equivalent H(2) and four equivalent H(3) atoms to form MgH8 hexagonal bipyramids that share edges with four equivalent B(1)H4 tetrahedra. In the second Mg site, Mg(2) is bonded in a body-centered cubic geometry to eight equivalent H(1) atoms. B(1) is bonded to one H(2), one H(3), and two equivalent H(1) atoms to form BH4 tetrahedra that share  an edgeedge with one Mg(1)H8 hexagonal bipyramid. There are three inequivalent H sites. In the first H site, H(2) is bonded in a distorted L-shaped geometry to one Mg(1) and one B(1) atom. In the second H site, H(3) is bonded in an L-shaped geometry to one Mg(1) and one B(1) atom. In the third H site, H(1) is bonded in a distorted L-shaped geometry to one Mg(2) and one B(1) atom. is represented by the CIF card [CIF]
data_Mg(BH4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.971
_cell_length_b   7.971
_cell_length_c   7.971
_cell_angle_alpha   116.580
_cell_angle_beta   116.580
_cell_angle_gamma   96.033
_symmetry_Int_Tables_number   1
_cell_volume   374.445
_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
  Mg  Mg0  1  0.750  0.250  0.500  1.0
  Mg  Mg1  1  0.000  0.000  0.000  1.0
  Mg  Mg2  1  0.500  0.500  0.000  1.0
  Mg  Mg3  1  0.250  0.750  0.500  1.0
  B  B4  1  0.644  0.410  0.765  1.0
  B  B5  1  0.160  0.894  0.265  1.0
  B  B6  1  0.629  0.894  0.735  1.0
  B  B7  1  0.644  0.879  0.235  1.0
  B  B8  1  0.106  0.840  0.735  1.0
  B  B9  1  0.590  0.356  0.235  1.0
  B  B10  1  0.121  0.356  0.765  1.0
  B  B11  1  0.106  0.371  0.265  1.0
  H  H12  1  0.738  0.451  0.958  1.0
  H  H13  1  0.492  0.451  0.713  1.0
  H  H14  1  0.201  0.988  0.458  1.0
  H  H15  1  0.530  0.988  0.787  1.0
  H  H16  1  0.738  0.780  0.287  1.0
  H  H17  1  0.492  0.780  0.042  1.0
  H  H18  1  0.201  0.742  0.213  1.0
  H  H19  1  0.530  0.742  0.542  1.0
  H  H20  1  0.012  0.799  0.542  1.0
  H  H21  1  0.258  0.799  0.787  1.0
  H  H22  1  0.549  0.262  0.042  1.0
  H  H23  1  0.220  0.262  0.713  1.0
  H  H24  1  0.012  0.470  0.213  1.0
  H  H25  1  0.258  0.470  0.458  1.0
  H  H26  1  0.549  0.508  0.287  1.0
  H  H27  1  0.220  0.508  0.958  1.0
  H  H28  1  0.588  0.951  0.363  1.0
  H  H29  1  0.701  0.838  0.863  1.0
  H  H30  1  0.975  0.838  0.137  1.0
  H  H31  1  0.588  0.225  0.637  1.0
  H  H32  1  0.162  0.299  0.137  1.0
  H  H33  1  0.049  0.412  0.637  1.0
  H  H34  1  0.775  0.412  0.363  1.0
  H  H35  1  0.162  0.025  0.863  1.0
  H  H36  1  0.758  0.511  0.753  1.0
  H  H37  1  0.261  0.008  0.253  1.0
  H  H38  1  0.756  0.008  0.747  1.0
  H  H39  1  0.758  0.006  0.247  1.0
  H  H40  1  0.992  0.739  0.747  1.0
  H  H41  1  0.489  0.242  0.247  1.0
  H  H42  1  0.994  0.242  0.753  1.0
  H  H43  1  0.992  0.244  0.253  1.0
[/CIF]
.