data_HgC5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.91
_cell_length_b   2.91
_cell_length_c   6.7
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HgC5
_chemical_formula_sum   'Hg1 C5'
_cell_volume   56.57
_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
  Hg  Hg5  1  0.45  0.45  0.35  1.0
  C  C0  1  0.0  0.0  0.11  1.0
  C  C1  1  0.0  0.0  0.59  1.0
  C  C2  1  0.45  0.45  0.97  1.0
  C  C3  1  0.45  0.45  0.73  1.0
  C  C4  1  0.0  0.0  0.0  1.0

data_HgC5
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.11
_cell_length_b   4.11
_cell_length_c   6.7
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   HgC5
_chemical_formula_sum   'Hg2 C10'
_cell_volume   113.15
_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
  Hg  Hg0  2  0.45  0.0  0.35  1.0
  C  C1  2  0.0  0.0  0.0  1.0
  C  C2  2  0.0  0.0  0.11  1.0
  C  C3  2  0.0  0.0  0.59  1.0
  C  C4  2  0.45  0.0  0.73  1.0
  C  C5  2  0.45  0.0  0.97  1.0

Hg C C C C C
Hg C C C C C 0 5 o o o 0 1 o o o 0 1 o + o 0 1 + o o 0 1 + + o 0 2 o o o 0 2 o + o 0 2 + o o 0 2 + + o 0 0 + o o 0 0 o + o 0 3 o o - 0 4 o o o 1 5 o o o 1 3 o o - 2 4 - - o 2 4 - o o 2 4 o - o 2 4 o o o 2 5 o o + 3 5 o o + 3 5 o + + 3 5 + o + 3 4 o o o 
HgC5 crystallizes in the monoclinic Cm space group. Hg(1) is bonded in a 8-coordinate geometry to one C(3), one C(4), three equivalent C(1), and three equivalent C(2) atoms. The Hg(1)-C(3) bond length is 2.55 Å. The Hg(1)-C(4) bond length is 2.55 Å. There is one shorter (2.46 Å) and two longer (2.62 Å) Hg(1)-C(1) bond lengths. There is one shorter (2.46 Å) and two longer (2.62 Å) Hg(1)-C(2) bond lengths. There are five inequivalent C sites. In the first C site, C(1) is bonded in a single-bond geometry to three equivalent Hg(1) and one C(5) atom. The C(1)-C(5) bond length is 0.74 Å. In the second C site, C(2) is bonded in a 4-coordinate geometry to three equivalent Hg(1) and one C(4) atom. The C(2)-C(4) bond length is 2.09 Å. In the third C site, C(3) is bonded in a 5-coordinate geometry to one Hg(1), one C(4), and three equivalent C(5) atoms. The C(3)-C(4) bond length is 1.60 Å. There is one shorter (1.87 Å) and two longer (2.07 Å) C(3)-C(5) bond lengths. In the fourth C site, C(4) is bonded in a distorted trigonal planar geometry to one Hg(1), one C(2), and one C(3) atom. In the fifth C site, C(5) is bonded in a single-bond geometry to one C(1) and three equivalent C(3) atoms.