data_HfMg3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.48
_cell_length_b   5.48
_cell_length_c   5.48
_cell_angle_alpha   132.05
_cell_angle_beta   132.05
_cell_angle_gamma   70.14
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfMg3
_chemical_formula_sum   'Hf1 Mg3'
_cell_volume   88.91
_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
  Hf  Hf0  1  0.0  0.0  0.48  1.0
  Mg  Mg1  1  0.0  0.0  0.0  1.0
  Mg  Mg2  1  0.0  0.23  0.24  1.0
  Mg  Mg3  1  0.23  0.0  0.24  1.0

data_HfMg3
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.3
_cell_length_b   6.3
_cell_length_c   5.48
_cell_angle_alpha   90.0
_cell_angle_beta   125.07
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   HfMg3
_chemical_formula_sum   'Hf2 Mg6'
_cell_volume   177.83
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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
  Hf  Hf0  2  0.0  0.0  0.48  1.0
  Mg  Mg1  4  0.39  0.39  0.02  1.0
  Mg  Mg2  2  0.0  0.0  0.0  1.0

Hf Mg Mg Mg
Mg3Hf crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted L-shaped geometry to two equivalent Mg(2) and one Hf(1) atom. Both Mg(1)-Mg(2) bond lengths are 1.05 Å. The Mg(1)-Hf(1) bond length is 2.82 Å. In the second Mg site, Mg(2) is bonded in a distorted single-bond geometry to one Mg(1) and two equivalent Hf(1) atoms. There is one shorter (2.35 Å) and one longer (3.49 Å) Mg(2)-Hf(1) bond length. Hf(1) is bonded in a 5-coordinate geometry to one Mg(1) and four equivalent Mg(2) atoms.