data_SiC3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.19
_cell_length_b   3.19
_cell_length_c   3.19
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SiC3
_chemical_formula_sum   'Si1 C3'
_cell_volume   32.49
_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  Si3  1  0.0  0.0  0.0  1.0
  C  C0  1  0.6  0.6  0.0  1.0
  C  C1  1  0.6  0.0  0.6  1.0
  C  C2  1  0.0  0.6  0.6  1.0

data_SiC3
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.51
_cell_length_b   4.51
_cell_length_c   5.53
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   SiC3
_chemical_formula_sum   'Si3 C9'
_cell_volume   97.47
_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
  Si  Si0  3  0.0  0.0  0.0  1.0
  C  C1  9  0.2  0.4  0.4  1.0

Si C C C
Si C C C 0 1 - - o 0 2 - o - 0 3 o - - 1 3 + o - 1 2 o + - 2 3 + - o 
SiC3 is Uranium Silicide structured and crystallizes in the trigonal R3m space group. Si(1) is bonded in a 9-coordinate geometry to nine equivalent C(1) atoms. There are three shorter (1.83 Å) and six longer (2.30 Å) Si(1)-C(1) bond lengths. C(1) is bonded in a 5-coordinate geometry to three equivalent Si(1) and two equivalent C(1) atoms. Both C(1)-C(1) bond lengths are 1.83 Å.