data_Cr2C
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.65
_cell_length_b   4.65
_cell_length_c   2.83
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Cr2C
_chemical_formula_sum   'Cr4 C2'
_cell_volume   61.19
_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
  Cr  Cr2  1  0.38  0.38  0.0  1.0
  Cr  Cr3  1  0.27  0.27  0.0  1.0
  Cr  Cr4  1  0.94  0.71  0.42  1.0
  Cr  Cr5  1  0.71  0.94  0.42  1.0
  C  C0  1  0.0  0.0  0.0  1.0
  C  C1  1  0.32  0.32  0.42  1.0

data_Cr2C
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.58
_cell_length_b   6.58
_cell_length_c   2.83
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Cr2C
_chemical_formula_sum   'Cr8 C4'
_cell_volume   122.39
_cell_formula_units_Z   4
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
  Cr  Cr0  4  0.32  0.38  0.42  1.0
  Cr  Cr1  2  0.27  0.0  0.0  1.0
  Cr  Cr2  2  0.38  0.0  0.0  1.0
  C  C3  2  0.0  0.0  0.0  1.0
  C  C4  2  0.32  0.0  0.42  1.0

Cr Cr Cr Cr C C
Cr Cr Cr Cr C C 0 1 o o o 0 5 o o o 1 4 o o o 1 5 o o o 2 3 o o o 2 4 + + o 3 4 + + o 
Cr2C crystallizes in the monoclinic Cm space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 3-coordinate geometry to one Cr(2) and two equivalent C(2) atoms. The Cr(1)-Cr(2) bond length is 0.78 Å. There is one shorter (1.24 Å) and one longer (1.70 Å) Cr(1)-C(2) bond length. In the second Cr site, Cr(2) is bonded in a 4-coordinate geometry to one Cr(1), one C(1), and two equivalent C(2) atoms. The Cr(2)-C(1) bond length is 1.75 Å. There is one shorter (1.24 Å) and one longer (1.70 Å) Cr(2)-C(2) bond length. In the third Cr site, Cr(3) is bonded in a 4-coordinate geometry to one Cr(3), one C(2), and two equivalent C(1) atoms. The Cr(3)-Cr(3) bond length is 1.53 Å. The Cr(3)-C(2) bond length is 2.52 Å. There is one shorter (1.81 Å) and one longer (2.16 Å) Cr(3)-C(1) bond length. There are two inequivalent C sites. In the first C site, C(1) is bonded in a 5-coordinate geometry to one Cr(2) and four equivalent Cr(3) atoms. In the second C site, C(2) is bonded in a 6-coordinate geometry to two equivalent Cr(1), two equivalent Cr(2), and two equivalent Cr(3) atoms.