data_Si5C4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.11
_cell_length_b   5.11
_cell_length_c   5.11
_cell_angle_alpha   106.53
_cell_angle_beta   106.53
_cell_angle_gamma   115.53
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si5C4
_chemical_formula_sum   'Si5 C4'
_cell_volume   102.13
_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
  Si  Si4  1  0.0  0.0  0.0  1.0
  Si  Si5  1  0.86  0.14  0.73  1.0
  Si  Si6  1  0.14  0.86  0.73  1.0
  Si  Si7  1  0.92  0.92  0.0  1.0
  Si  Si8  1  0.14  0.14  0.73  1.0
  C  C0  1  0.0  0.82  0.0  1.0
  C  C1  1  0.0  0.29  0.0  1.0
  C  C2  1  0.29  0.0  0.0  1.0
  C  C3  1  0.82  0.0  0.0  1.0

data_Si5C4
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.46
_cell_length_b   8.65
_cell_length_c   5.11
_cell_angle_alpha   90.0
_cell_angle_beta   122.23
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Si5C4
_chemical_formula_sum   'Si10 C8'
_cell_volume   204.27
_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
  Si  Si0  4  0.27  0.14  0.27  1.0
  Si  Si1  2  -0.0  0.0  0.0  1.0
  Si  Si2  2  0.41  0.0  0.27  1.0
  Si  Si3  2  0.42  0.5  -0.0  1.0
  C  C4  4  0.15  0.15  -0.0  1.0
  C  C5  4  0.41  0.41  -0.0  1.0

Si Si Si Si Si C C C C
Si Si Si Si Si C C C C 0 3 - - o 0 5 o - o 0 8 - o o 1 6 + o + 1 4 + o o 2 7 o + + 2 4 o + o 3 5 + o o 3 8 o + o 5 7 o + o 6 8 - o o 
Si5C4 is Indium-like structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two Si5C4 clusters. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 1-coordinate geometry to one Si(3), one Si(4), and two equivalent C(1) atoms. The Si(1)-Si(3) bond length is 0.44 Å. The Si(1)-Si(4) bond length is 1.91 Å. Both Si(1)-C(1) bond lengths are 0.90 Å. In the second Si site, Si(2) is bonded in a single-bond geometry to one Si(4) and one C(2) atom. The Si(2)-Si(4) bond length is 1.44 Å. The Si(2)-C(2) bond length is 1.18 Å. In the third Si site, Si(3) is bonded in a T-shaped geometry to one Si(1) and two equivalent C(1) atoms. Both Si(3)-C(1) bond lengths are 0.76 Å. In the fourth Si site, Si(4) is bonded in a 5-coordinate geometry to one Si(1), two equivalent Si(2), and two equivalent C(2) atoms. Both Si(4)-C(2) bond lengths are 1.87 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a 2-coordinate geometry to one Si(1) and one Si(3) atom. In the second C site, C(2) is bonded in a distorted single-bond geometry to one Si(2) and one Si(4) atom.