data_HfMg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.71
_cell_length_b   4.71
_cell_length_c   5.6
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfMg
_chemical_formula_sum   'Hf2 Mg2'
_cell_volume   107.69
_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
  Hf  Hf0  1  0.0  0.0  0.8  1.0
  Hf  Hf1  1  0.0  0.0  0.0  1.0
  Mg  Mg2  1  0.36  0.36  0.2  1.0
  Mg  Mg3  1  0.0  0.72  0.4  1.0

data_HfMg
_symmetry_space_group_name_H-M   P1
_cell_length_a   4.71
_cell_length_b   4.71
_cell_length_c   5.6
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfMg
_chemical_formula_sum   'Hf2 Mg2'
_cell_volume   107.69
_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
  Hf  Hf0  1  0.0  0.0  0.0  1.0
  Hf  Hf1  1  0.0  0.0  0.8  1.0
  Mg  Mg2  1  0.0  0.72  0.4  1.0
  Mg  Mg3  1  0.36  0.36  0.2  1.0

Hf Hf Mg Mg
Hf Hf Mg Mg 0 1 o o + 0 3 o - o 1 2 o o o 1 3 o - o 2 3 + o o 2 3 o o o 2 3 o - o 
Mg(Hf) crystallizes in the triclinic P1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted single-bond geometry to three equivalent Mg(2) and one Hf(2) atom. There are a spread of Mg(1)-Mg(2) bond distances ranging from 2.84-3.13 Å. The Mg(1)-Hf(2) bond length is 2.03 Å. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to three equivalent Mg(1), one Hf(1), and one Hf(2) atom. The Mg(2)-Hf(1) bond length is 2.60 Å. The Mg(2)-Hf(2) bond length is 2.60 Å. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a distorted bent 150 degrees geometry to one Mg(2) and one Hf(2) atom. The Hf(1)-Hf(2) bond length is 1.12 Å. In the second Hf site, Hf(2) is bonded in a 2-coordinate geometry to one Mg(1), one Mg(2), and one Hf(1) atom.