data_HfC2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.57
_cell_length_b   3.57
_cell_length_c   11.36
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfC2
_chemical_formula_sum   'Hf4 C8'
_cell_volume   125.39
_cell_formula_units_Z   4
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  Hf8  1  0.79  0.03  0.92  1.0
  Hf  Hf9  1  0.0  0.06  0.24  1.0
  Hf  Hf10  1  0.0  0.06  0.43  1.0
  Hf  Hf11  1  0.79  0.03  0.11  1.0
  C  C0  1  0.0  0.0  0.68  1.0
  C  C1  1  0.0  0.0  0.0  1.0
  C  C2  1  0.03  0.66  0.52  1.0
  C  C3  1  0.75  0.44  0.84  1.0
  C  C4  1  0.97  0.66  0.52  1.0
  C  C5  1  0.0  0.87  0.52  1.0
  C  C6  1  0.79  0.22  0.84  1.0
  C  C7  1  0.82  0.44  0.84  1.0

data_HfC2
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.57
_cell_length_b   3.57
_cell_length_c   11.36
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfC2
_chemical_formula_sum   'Hf4 C8'
_cell_volume   125.39
_cell_formula_units_Z   4
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  0.06  0.24  1.0
  Hf  Hf1  1  0.0  0.06  0.43  1.0
  Hf  Hf2  1  0.79  0.03  0.11  1.0
  Hf  Hf3  1  0.79  0.03  0.92  1.0
  C  C4  1  0.0  0.0  0.0  1.0
  C  C5  1  0.0  0.0  0.68  1.0
  C  C6  1  0.0  0.87  0.52  1.0
  C  C7  1  0.03  0.66  0.52  1.0
  C  C8  1  0.75  0.44  0.84  1.0
  C  C9  1  0.79  0.22  0.84  1.0
  C  C10  1  0.82  0.44  0.84  1.0
  C  C11  1  0.97  0.66  0.52  1.0

Hf Hf Hf Hf C C C C C C C C
HfC2 crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one HfC2 cluster. There are four inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a distorted bent 150 degrees geometry to one C(2) and one C(7) atom. The Hf(1)-C(2) bond length is 1.22 Å. The Hf(1)-C(7) bond length is 1.16 Å. In the second Hf site, Hf(2) is bonded in a distorted bent 150 degrees geometry to one Hf(3) and one Hf(4) atom. The Hf(2)-Hf(3) bond length is 2.16 Å. The Hf(2)-Hf(4) bond length is 1.66 Å. In the third Hf site, Hf(3) is bonded in a single-bond geometry to one Hf(2) and one C(6) atom. The Hf(3)-C(6) bond length is 1.16 Å. In the fourth Hf site, Hf(4) is bonded in a single-bond geometry to one Hf(2) and one C(2) atom. The Hf(4)-C(2) bond length is 1.51 Å. There are eight inequivalent C sites. In the first C site, C(1) is bonded in a single-bond geometry to one C(6) atom. The C(1)-C(6) bond length is 1.89 Å. In the second C site, C(2) is bonded in a water-like geometry to one Hf(1) and one Hf(4) atom. In the third C site, C(3) is bonded in a distorted single-bond geometry to one C(5) atom. The C(3)-C(5) bond length is 0.22 Å. In the fourth C site, C(4) is bonded in a single-bond geometry to one C(8) atom. The C(4)-C(8) bond length is 0.22 Å. In the fifth C site, C(5) is bonded in a distorted bent 120 degrees geometry to one C(3) and one C(6) atom. The C(5)-C(6) bond length is 0.72 Å. In the sixth C site, C(6) is bonded in a 2-coordinate geometry to one Hf(3), one C(1), and one C(5) atom. In the seventh C site, C(7) is bonded in a distorted single-bond geometry to one Hf(1) and one C(8) atom. The C(7)-C(8) bond length is 0.72 Å. In the eighth C site, C(8) is bonded in a distorted single-bond geometry to one C(4) and one C(7) atom.