data_RhC2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.99
_cell_length_b   4.99
_cell_length_c   4.31
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   150.1
_symmetry_Int_Tables_number   1
_chemical_formula_structural   RhC2
_chemical_formula_sum   'Rh2 C4'
_cell_volume   53.47
_cell_formula_units_Z   2
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
  Rh  Rh4  1  0.29  0.64  0.23  1.0
  Rh  Rh5  1  0.29  0.36  0.08  1.0
  C  C0  1  0.29  0.99  0.23  1.0
  C  C1  1  0.29  0.54  0.23  1.0
  C  C2  1  0.29  0.46  0.08  1.0
  C  C3  1  0.29  0.01  0.08  1.0

data_RhC2
_symmetry_space_group_name_H-M   P-1
_cell_length_a   2.57
_cell_length_b   4.31
_cell_length_c   4.99
_cell_angle_alpha   90.0
_cell_angle_beta   104.95
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   RhC2
_chemical_formula_sum   'Rh2 C4'
_cell_volume   53.47
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-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
  Rh  Rh0  2  0.36  0.58  0.86  1.0
  C  C1  2  0.01  0.58  0.51  1.0
  C  C2  2  0.46  0.58  0.96  1.0

Rh Rh C C C C
RhC2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one acetylene molecule and one RhC cluster. In the RhC cluster, Rh(1) is bonded in a single-bond geometry to one C(2) atom. The Rh(1)-C(2) bond length is 0.48 Å. C(2) is bonded in a bent 120 degrees geometry to one Rh(1) and one C(2) atom. The C(2)-C(2) bond length is 0.80 Å.