data_HfMgCr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.61
_cell_length_b   4.61
_cell_length_c   4.61
_cell_angle_alpha   120.77
_cell_angle_beta   120.77
_cell_angle_gamma   88.67
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfMgCr2
_chemical_formula_sum   'Hf1 Mg1 Cr2'
_cell_volume   68.64
_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  Hf2  1  0.0  0.0  0.3  1.0
  Mg  Mg3  1  0.0  0.0  0.0  1.0
  Cr  Cr0  1  0.28  0.0  0.65  1.0
  Cr  Cr1  1  0.0  0.28  0.65  1.0

data_HfMgCr2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.45
_cell_length_b   6.45
_cell_length_c   4.61
_cell_angle_alpha   90.0
_cell_angle_beta   134.34
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   HfMgCr2
_chemical_formula_sum   'Hf2 Mg2 Cr4'
_cell_volume   137.28
_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  0.2  0.5  0.7  1.0
  Mg  Mg1  2  0.0  0.0  0.0  1.0
  Cr  Cr2  4  0.49  0.14  0.63  1.0

Hf Mg Cr Cr
MgHfCr2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded in a 5-coordinate geometry to one Hf(1) and four equivalent Cr(1) atoms. The Mg(1)-Hf(1) bond length is 1.39 Å. There are two shorter (2.53 Å) and two longer (2.85 Å) Mg(1)-Cr(1) bond lengths. Hf(1) is bonded in a 3-coordinate geometry to one Mg(1) and two equivalent Cr(1) atoms. Both Hf(1)-Cr(1) bond lengths are 1.46 Å. Cr(1) is bonded in a distorted single-bond geometry to two equivalent Mg(1) and one Hf(1) atom.