data_HfSi5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.02
_cell_length_b   5.02
_cell_length_c   5.02
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfSi5
_chemical_formula_sum   'Hf1 Si5'
_cell_volume   89.57
_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  0.33  0.33  0.33  1.0
  Si  Si1  1  0.0  0.0  0.0  1.0
  Si  Si2  1  0.66  0.66  0.66  1.0
  Si  Si3  1  0.44  0.66  0.44  1.0
  Si  Si4  1  0.44  0.44  0.66  1.0
  Si  Si5  1  0.66  0.44  0.44  1.0

data_HfSi5
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.02
_cell_length_b   5.02
_cell_length_c   12.3
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   HfSi5
_chemical_formula_sum   'Hf3 Si15'
_cell_volume   268.71
_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  0.67  1.0
  Si  Si1  9  0.07  0.15  0.49  1.0
  Si  Si2  3  0.0  0.0  0.0  1.0
  Si  Si3  3  0.0  0.0  0.34  1.0

Hf Si Si Si Si Si
HfSi5 crystallizes in the trigonal R3m space group. Hf(1) is bonded to three equivalent Si(1), three equivalent Si(2), and six equivalent Si(3) atoms to form a mixture of edge and corner-sharing HfSi12 cuboctahedra. All Hf(1)-Si(1) bond lengths are 2.90 Å. All Hf(1)-Si(2) bond lengths are 2.90 Å. There are three shorter (2.39 Å) and three longer (2.88 Å) Hf(1)-Si(3) bond lengths. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a trigonal planar geometry to three equivalent Hf(1) atoms. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to three equivalent Hf(1) and three equivalent Si(3) atoms. All Si(2)-Si(3) bond lengths are 1.93 Å. In the third Si site, Si(3) is bonded in a 5-coordinate geometry to two equivalent Hf(1), one Si(2), and two equivalent Si(3) atoms. Both Si(3)-Si(3) bond lengths are 1.11 Å.