The structure described by Sm2Co18Si4C3 crystallizes in the monoclinic C2/m space group. Sm(1) is bonded in a 3-coordinate geometry to two equivalent Co(5), four equivalent Co(3), one C(2), and two equivalent C(1) atoms. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded in a single-bond geometry to one Co(3), one Co(5), one Si(2), one Si(3), and one C(2) atom. In the second Co site, Co(2) is bonded in a single-bond geometry to one Co(5), two equivalent Co(3), one Si(1), one Si(2), and one C(1) atom. In the third Co site, Co(3) is bonded to two equivalent Sm(1), one Co(1), one Co(5), two equivalent Co(2), two equivalent Co(3), two equivalent Co(4), one Si(1), and one Si(2) atom to form distorted CoSm2Co8Si2 cuboctahedra that share corners with two equivalent Co(3)Sm2Co8Si2 cuboctahedra, corners with three equivalent C(1)Sm2Co4 octahedra, corners with three equivalent C(2)Sm2Co4 octahedra,  an edgeedge with one C(1)Sm2Co4 octahedra, faces with four equivalent Co(3)Sm2Co8Si2 cuboctahedra, and  a faceface with one C(1)Sm2Co4 octahedra. The corner-sharing octahedral tilt angles range from 24-70°. In the fourth Co site, Co(4) is bonded in a single-bond geometry to one Co(5), two equivalent Co(3), one Si(2), one Si(3), and one C(1) atom. In the fifth Co site, Co(5) is bonded in a 14-coordinate geometry to two equivalent Sm(1), two equivalent Co(1), two equivalent Co(2), two equivalent Co(3), two equivalent Co(4), one Si(1), one Si(3), and two equivalent Si(2) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 10-coordinate geometry to two equivalent Co(5), four equivalent Co(2), and four equivalent Co(3) atoms. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to two equivalent Co(1), two equivalent Co(2), two equivalent Co(3), two equivalent Co(4), and two equivalent Co(5) atoms. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to two equivalent Co(5), four equivalent Co(1), and four equivalent Co(4) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded to two equivalent Sm(1), two equivalent Co(2), and two equivalent Co(4) atoms to form CSm2Co4 octahedra that share corners with six equivalent Co(3)Sm2Co8Si2 cuboctahedra, corners with two equivalent C(1)Sm2Co4 octahedra, corners with two equivalent C(2)Sm2Co4 octahedra, edges with two equivalent Co(3)Sm2Co8Si2 cuboctahedra, and faces with two equivalent Co(3)Sm2Co8Si2 cuboctahedra. The corner-sharing octahedral tilt angles range from 37-86°. In the second C site, C(2) is bonded to two equivalent Sm(1) and four equivalent Co(1) atoms to form CSm2Co4 octahedra that share corners with twelve equivalent Co(3)Sm2Co8Si2 cuboctahedra and corners with four equivalent C(1)Sm2Co4 octahedra. The corner-sharing octahedral tilt angles are 86°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Sm2Co18Si4C3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.671
_cell_length_b   7.671
_cell_length_c   6.397
_cell_angle_alpha   65.577
_cell_angle_beta   65.577
_cell_angle_gamma   80.147
_symmetry_Int_Tables_number   1
_cell_volume   312.092
_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
  Sm  Sm0  1  0.755  0.755  0.867  1.0
  Sm  Sm1  1  0.245  0.245  0.133  1.0
  Co  Co2  1  0.420  0.673  0.758  1.0
  Co  Co3  1  0.673  0.420  0.758  1.0
  Co  Co4  1  0.922  0.325  0.931  1.0
  Co  Co5  1  0.325  0.922  0.931  1.0
  Co  Co6  1  0.834  0.076  0.357  1.0
  Co  Co7  1  0.076  0.834  0.357  1.0
  Co  Co8  1  0.169  0.585  0.677  1.0
  Co  Co9  1  0.585  0.169  0.677  1.0
  Co  Co10  1  0.580  0.327  0.242  1.0
  Co  Co11  1  0.327  0.580  0.242  1.0
  Co  Co12  1  0.078  0.675  0.069  1.0
  Co  Co13  1  0.675  0.078  0.069  1.0
  Co  Co14  1  0.166  0.924  0.643  1.0
  Co  Co15  1  0.924  0.166  0.643  1.0
  Co  Co16  1  0.831  0.415  0.323  1.0
  Co  Co17  1  0.415  0.831  0.323  1.0
  Co  Co18  1  0.752  0.752  0.381  1.0
  Co  Co19  1  0.248  0.248  0.619  1.0
  Si  Si20  1  0.000  0.000  0.000  1.0
  Si  Si21  1  0.500  0.000  0.500  1.0
  Si  Si22  1  0.000  0.500  0.500  1.0
  Si  Si23  1  0.500  0.500  0.500  1.0
  C  C24  1  0.500  0.000  0.000  1.0
  C  C25  1  0.000  0.500  0.000  1.0
  C  C26  1  0.500  0.500  0.000  1.0
[/CIF]
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The structure described by Sm2Co18Si4C3 crystallizes in the monoclinic C2/m space group. Sm(1) is bonded in a 3-coordinate geometry to two equivalent Co(5), four equivalent Co(3), one C(2), and two equivalent C(1) atoms. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded in a single-bond geometry to one Co(3), one Co(5), one Si(2), one Si(3), and one C(2) atom. In the second Co site, Co(2) is bonded in a single-bond geometry to one Co(5), two equivalent Co(3), one Si(1), one Si(2), and one C(1) atom. In the third Co site, Co(3) is bonded to two equivalent Sm(1), one Co(1), one Co(5), two equivalent Co(2), two equivalent Co(3), two equivalent Co(4), one Si(1), and one Si(2) atom to form distorted CoSm2Co8Si2 cuboctahedra that share corners with two equivalent Co(3)Sm2Co8Si2 cuboctahedra, corners with three equivalent C(1)Sm2Co4 octahedra, corners with three equivalent C(2)Sm2Co4 octahedra,  an edgeedge with one C(1)Sm2Co4 octahedra, faces with four equivalent Co(3)Sm2Co8Si2 cuboctahedra, and  a faceface with one C(1)Sm2Co4 octahedra. The corner-sharing octahedral tilt angles range from 24-70°. In the fourth Co site, Co(4) is bonded in a single-bond geometry to one Co(5), two equivalent Co(3), one Si(2), one Si(3), and one C(1) atom. In the fifth Co site, Co(5) is bonded in a 14-coordinate geometry to two equivalent Sm(1), two equivalent Co(1), two equivalent Co(2), two equivalent Co(3), two equivalent Co(4), one Si(1), one Si(3), and two equivalent Si(2) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 10-coordinate geometry to two equivalent Co(5), four equivalent Co(2), and four equivalent Co(3) atoms. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to two equivalent Co(1), two equivalent Co(2), two equivalent Co(3), two equivalent Co(4), and two equivalent Co(5) atoms. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to two equivalent Co(5), four equivalent Co(1), and four equivalent Co(4) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded to two equivalent Sm(1), two equivalent Co(2), and two equivalent Co(4) atoms to form CSm2Co4 octahedra that share corners with six equivalent Co(3)Sm2Co8Si2 cuboctahedra, corners with two equivalent C(1)Sm2Co4 octahedra, corners with two equivalent C(2)Sm2Co4 octahedra, edges with two equivalent Co(3)Sm2Co8Si2 cuboctahedra, and faces with two equivalent Co(3)Sm2Co8Si2 cuboctahedra. The corner-sharing octahedral tilt angles range from 37-86°. In the second C site, C(2) is bonded to two equivalent Sm(1) and four equivalent Co(1) atoms to form CSm2Co4 octahedra that share corners with twelve equivalent Co(3)Sm2Co8Si2 cuboctahedra and corners with four equivalent C(1)Sm2Co4 octahedra. The corner-sharing octahedral tilt angles are 86°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Sm2Co18Si4C3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.671
_cell_length_b   7.671
_cell_length_c   6.397
_cell_angle_alpha   65.577
_cell_angle_beta   65.577
_cell_angle_gamma   80.147
_symmetry_Int_Tables_number   1
_cell_volume   312.092
_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
  Sm  Sm0  1  0.755  0.755  0.867  1.0
  Sm  Sm1  1  0.245  0.245  0.133  1.0
  Co  Co2  1  0.420  0.673  0.758  1.0
  Co  Co3  1  0.673  0.420  0.758  1.0
  Co  Co4  1  0.922  0.325  0.931  1.0
  Co  Co5  1  0.325  0.922  0.931  1.0
  Co  Co6  1  0.834  0.076  0.357  1.0
  Co  Co7  1  0.076  0.834  0.357  1.0
  Co  Co8  1  0.169  0.585  0.677  1.0
  Co  Co9  1  0.585  0.169  0.677  1.0
  Co  Co10  1  0.580  0.327  0.242  1.0
  Co  Co11  1  0.327  0.580  0.242  1.0
  Co  Co12  1  0.078  0.675  0.069  1.0
  Co  Co13  1  0.675  0.078  0.069  1.0
  Co  Co14  1  0.166  0.924  0.643  1.0
  Co  Co15  1  0.924  0.166  0.643  1.0
  Co  Co16  1  0.831  0.415  0.323  1.0
  Co  Co17  1  0.415  0.831  0.323  1.0
  Co  Co18  1  0.752  0.752  0.381  1.0
  Co  Co19  1  0.248  0.248  0.619  1.0
  Si  Si20  1  0.000  0.000  0.000  1.0
  Si  Si21  1  0.500  0.000  0.500  1.0
  Si  Si22  1  0.000  0.500  0.500  1.0
  Si  Si23  1  0.500  0.500  0.500  1.0
  C  C24  1  0.500  0.000  0.000  1.0
  C  C25  1  0.000  0.500  0.000  1.0
  C  C26  1  0.500  0.500  0.000  1.0
[/CIF]
.