data_MgAl3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.51
_cell_length_b   6.51
_cell_length_c   5.05
_cell_angle_alpha   104.96
_cell_angle_beta   104.96
_cell_angle_gamma   126.87
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgAl3
_chemical_formula_sum   'Mg2 Al6'
_cell_volume   139.87
_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  Mg6  1  0.73  0.82  0.09  1.0
  Mg  Mg7  1  0.18  0.18  0.03  1.0
  Al  Al0  1  0.73  0.9  0.09  1.0
  Al  Al1  1  0.18  0.27  0.03  1.0
  Al  Al2  1  0.73  0.64  0.09  1.0
  Al  Al3  1  0.18  0.36  0.03  1.0
  Al  Al4  1  0.73  0.73  0.09  1.0
  Al  Al5  1  0.18  0.1  0.03  1.0

data_MgAl3
_symmetry_space_group_name_H-M   P-1
_cell_length_a   5.05
_cell_length_b   5.05
_cell_length_c   6.51
_cell_angle_alpha   104.96
_cell_angle_beta   104.96
_cell_angle_gamma   109.47
_symmetry_Int_Tables_number   2
_chemical_formula_structural   MgAl3
_chemical_formula_sum   'Mg2 Al6'
_cell_volume   139.87
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-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  2  0.21  0.18  0.46  1.0
  Al  Al1  2  0.13  0.1  0.37  1.0
  Al  Al2  2  0.3  0.27  0.54  1.0
  Al  Al3  2  0.39  0.36  0.63  1.0

Mg Mg Al Al Al Al Al Al
Al3Mg is Cyanogen Chloride-derived structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two Al3Mg clusters. Mg(1) is bonded in a linear geometry to one Al(1) and one Al(2) atom. The Mg(1)-Al(1) bond length is 0.56 Å. The Mg(1)-Al(2) bond length is 0.56 Å. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded in a single-bond geometry to one Mg(1) atom. In the second Al site, Al(2) is bonded in a distorted linear geometry to one Mg(1) and one Al(3) atom. The Al(2)-Al(3) bond length is 0.56 Å. In the third Al site, Al(3) is bonded in a single-bond geometry to one Al(2) atom.