data_HfMg2Cl
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.16
_cell_length_b   5.16
_cell_length_c   5.16
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfMg2Cl
_chemical_formula_sum   'Hf1 Mg2 Cl1'
_cell_volume   97.16
_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  Hf1  1  0.65  0.65  0.65  1.0
  Mg  Mg2  1  0.82  0.82  0.82  1.0
  Mg  Mg3  1  0.47  0.47  0.47  1.0
  Cl  Cl0  1  0.0  0.0  0.0  1.0

data_HfMg2Cl
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.16
_cell_length_b   5.16
_cell_length_c   12.64
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   HfMg2Cl
_chemical_formula_sum   'Hf3 Mg6 Cl3'
_cell_volume   291.48
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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  3  0.0  0.0  0.35  1.0
  Mg  Mg1  3  0.0  0.0  0.18  1.0
  Mg  Mg2  3  0.0  0.0  0.53  1.0
  Cl  Cl3  3  0.0  0.0  0.0  1.0

Hf Mg Mg Cl
Mg2HfCl crystallizes in the trigonal R3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted single-bond geometry to one Hf(1) and one Cl(1) atom. The Mg(1)-Hf(1) bond length is 2.22 Å. The Mg(1)-Cl(1) bond length is 2.22 Å. In the second Mg site, Mg(2) is bonded in a distorted single-bond geometry to one Hf(1) atom. The Mg(2)-Hf(1) bond length is 2.22 Å. Hf(1) is bonded to one Mg(1), one Mg(2), and three equivalent Cl(1) atoms to form HfMg2Cl3 trigonal bipyramids that share corners with six equivalent Hf(1)Mg2Cl3 trigonal bipyramids and  a cornercorner with one Cl(1)Hf3Mg trigonal pyramid. All Hf(1)-Cl(1) bond lengths are 2.99 Å. Cl(1) is bonded to one Mg(1) and three equivalent Hf(1) atoms to form distorted ClHf3Mg trigonal pyramids that share  a cornercorner with one Hf(1)Mg2Cl3 trigonal bipyramid and corners with six equivalent Cl(1)Hf3Mg trigonal pyramids.