The material described by Sm2Fe17C2 crystallizes in the monoclinic C2/m space group. Sm(1) is bonded in a distorted bent 120 degrees geometry to one Fe(3), one Fe(4), two equivalent Fe(5), two equivalent Fe(6), three equivalent Fe(1), and two equivalent C(1) atoms. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent Sm(1), one Fe(3), two equivalent Fe(2), two equivalent Fe(5), two equivalent Fe(6), and two equivalent Fe(7) atoms to form distorted FeSm3Fe9 cuboctahedra that share corners with two equivalent Fe(5)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(6)Sm2Fe10 cuboctahedra, corners with three equivalent Fe(4)Sm2Fe10 cuboctahedra, corners with four equivalent Fe(1)Sm3Fe9 cuboctahedra, corners with four equivalent C(1)Sm2Fe4 octahedra,  an edgeedge with one Fe(4)Sm2Fe10 cuboctahedra,  an edgeedge with one Fe(1)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(5)Sm2Fe10 cuboctahedra,  a faceface with one Fe(4)Sm2Fe10 cuboctahedra,  a faceface with one Fe(1)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(5)Sm2Fe10 cuboctahedra, faces with four equivalent Fe(6)Sm2Fe10 cuboctahedra, and faces with two equivalent C(1)Sm2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 63-69°. In the second Fe site, Fe(2) is bonded in a single-bond geometry to one Fe(1), one Fe(3), one Fe(4), one Fe(5), one Fe(6), and one C(1) atom. In the third Fe site, Fe(3) is bonded in a 14-coordinate geometry to one Sm(1), one Fe(1), one Fe(3), one Fe(4), two equivalent Fe(2), two equivalent Fe(5), two equivalent Fe(6), and four equivalent Fe(7) atoms. In the fourth Fe site, Fe(4) is bonded to two equivalent Sm(1), two equivalent Fe(3), four equivalent Fe(2), and four equivalent Fe(7) atoms to form distorted FeSm2Fe10 cuboctahedra that share corners with four equivalent Fe(5)Sm2Fe10 cuboctahedra, corners with four equivalent Fe(6)Sm2Fe10 cuboctahedra, corners with six equivalent Fe(1)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(1)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(1)Sm3Fe9 cuboctahedra, faces with four equivalent Fe(5)Sm2Fe10 cuboctahedra, faces with four equivalent Fe(6)Sm2Fe10 cuboctahedra, and faces with four equivalent C(1)Sm2Fe4 octahedra. In the fifth Fe site, Fe(5) is bonded to two equivalent Sm(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(6), and two equivalent Fe(7) atoms to form FeSm2Fe10 cuboctahedra that share corners with two equivalent Fe(4)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(5)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(6)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(1)Sm3Fe9 cuboctahedra, corners with two equivalent C(1)Sm2Fe4 octahedra, edges with two equivalent Fe(6)Sm2Fe10 cuboctahedra, edges with two equivalent Fe(1)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(4)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(5)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(6)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(1)Sm3Fe9 cuboctahedra, and faces with two equivalent C(1)Sm2Fe4 octahedra. The corner-sharing octahedral tilt angles are 44°. In the sixth Fe site, Fe(6) is bonded to two equivalent Sm(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(5), and two equivalent Fe(7) atoms to form distorted FeSm2Fe10 cuboctahedra that share corners with two equivalent Fe(4)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(5)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(6)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(1)Sm3Fe9 cuboctahedra, corners with four equivalent C(1)Sm2Fe4 octahedra,  an edgeedge with one Fe(6)Sm2Fe10 cuboctahedra, edges with two equivalent Fe(5)Sm2Fe10 cuboctahedra, edges with two equivalent C(1)Sm2Fe4 octahedra,  a faceface with one Fe(6)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(4)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(5)Sm2Fe10 cuboctahedra, and faces with four equivalent Fe(1)Sm3Fe9 cuboctahedra. The corner-sharing octahedral tilt angles range from 22-29°. In the seventh Fe site, Fe(7) is bonded in a single-bond geometry to one Fe(1), one Fe(4), one Fe(5), one Fe(6), two equivalent Fe(3), and one C(1) atom. C(1) is bonded to two equivalent Sm(1), two equivalent Fe(2), and two equivalent Fe(7) atoms to form CSm2Fe4 octahedra that share corners with two equivalent Fe(5)Sm2Fe10 cuboctahedra, corners with four equivalent Fe(6)Sm2Fe10 cuboctahedra, corners with four equivalent Fe(1)Sm3Fe9 cuboctahedra, corners with two equivalent C(1)Sm2Fe4 octahedra, edges with two equivalent Fe(6)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(4)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(5)Sm2Fe10 cuboctahedra, and faces with two equivalent Fe(1)Sm3Fe9 cuboctahedra. The corner-sharing octahedral tilt angles are 63°. is represented by the CIF card [CIF]
data_Sm2Fe17C2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.492
_cell_length_b   6.492
_cell_length_c   6.501
_cell_angle_alpha   83.726
_cell_angle_beta   83.726
_cell_angle_gamma   83.677
_symmetry_Int_Tables_number   1
_cell_volume   269.399
_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  0.347  0.347  0.333  1.0
  Sm  Sm1  1  0.653  0.653  0.667  1.0
  Fe  Fe2  1  0.658  0.658  0.147  1.0
  Fe  Fe3  1  0.656  0.146  0.659  1.0
  Fe  Fe4  1  0.146  0.656  0.659  1.0
  Fe  Fe5  1  0.342  0.342  0.853  1.0
  Fe  Fe6  1  0.344  0.854  0.341  1.0
  Fe  Fe7  1  0.854  0.344  0.341  1.0
  Fe  Fe8  1  0.096  0.096  0.096  1.0
  Fe  Fe9  1  0.904  0.904  0.904  1.0
  Fe  Fe10  1  0.000  0.000  0.500  1.0
  Fe  Fe11  1  0.000  0.500  0.000  1.0
  Fe  Fe12  1  0.500  0.000  0.000  1.0
  Fe  Fe13  1  0.714  0.286  0.000  1.0
  Fe  Fe14  1  0.286  0.001  0.714  1.0
  Fe  Fe15  1  0.999  0.714  0.286  1.0
  Fe  Fe16  1  0.714  0.999  0.286  1.0
  Fe  Fe17  1  0.001  0.286  0.714  1.0
  Fe  Fe18  1  0.286  0.714  0.000  1.0
  C  C19  1  0.500  0.000  0.500  1.0
  C  C20  1  0.000  0.500  0.500  1.0
[/CIF]
.
The material described by Sm2Fe17C2 crystallizes in the monoclinic C2/m space group. Sm(1) is bonded in a distorted bent 120 degrees geometry to one Fe(3), one Fe(4), two equivalent Fe(5), two equivalent Fe(6), three equivalent Fe(1), and two equivalent C(1) atoms. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent Sm(1), one Fe(3), two equivalent Fe(2), two equivalent Fe(5), two equivalent Fe(6), and two equivalent Fe(7) atoms to form distorted FeSm3Fe9 cuboctahedra that share corners with two equivalent Fe(5)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(6)Sm2Fe10 cuboctahedra, corners with three equivalent Fe(4)Sm2Fe10 cuboctahedra, corners with four equivalent Fe(1)Sm3Fe9 cuboctahedra, corners with four equivalent C(1)Sm2Fe4 octahedra,  an edgeedge with one Fe(4)Sm2Fe10 cuboctahedra,  an edgeedge with one Fe(1)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(5)Sm2Fe10 cuboctahedra,  a faceface with one Fe(4)Sm2Fe10 cuboctahedra,  a faceface with one Fe(1)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(5)Sm2Fe10 cuboctahedra, faces with four equivalent Fe(6)Sm2Fe10 cuboctahedra, and faces with two equivalent C(1)Sm2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 63-69°. In the second Fe site, Fe(2) is bonded in a single-bond geometry to one Fe(1), one Fe(3), one Fe(4), one Fe(5), one Fe(6), and one C(1) atom. In the third Fe site, Fe(3) is bonded in a 14-coordinate geometry to one Sm(1), one Fe(1), one Fe(3), one Fe(4), two equivalent Fe(2), two equivalent Fe(5), two equivalent Fe(6), and four equivalent Fe(7) atoms. In the fourth Fe site, Fe(4) is bonded to two equivalent Sm(1), two equivalent Fe(3), four equivalent Fe(2), and four equivalent Fe(7) atoms to form distorted FeSm2Fe10 cuboctahedra that share corners with four equivalent Fe(5)Sm2Fe10 cuboctahedra, corners with four equivalent Fe(6)Sm2Fe10 cuboctahedra, corners with six equivalent Fe(1)Sm3Fe9 cuboctahedra, edges with two equivalent Fe(1)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(1)Sm3Fe9 cuboctahedra, faces with four equivalent Fe(5)Sm2Fe10 cuboctahedra, faces with four equivalent Fe(6)Sm2Fe10 cuboctahedra, and faces with four equivalent C(1)Sm2Fe4 octahedra. In the fifth Fe site, Fe(5) is bonded to two equivalent Sm(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(6), and two equivalent Fe(7) atoms to form FeSm2Fe10 cuboctahedra that share corners with two equivalent Fe(4)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(5)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(6)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(1)Sm3Fe9 cuboctahedra, corners with two equivalent C(1)Sm2Fe4 octahedra, edges with two equivalent Fe(6)Sm2Fe10 cuboctahedra, edges with two equivalent Fe(1)Sm3Fe9 cuboctahedra, faces with two equivalent Fe(4)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(5)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(6)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(1)Sm3Fe9 cuboctahedra, and faces with two equivalent C(1)Sm2Fe4 octahedra. The corner-sharing octahedral tilt angles are 44°. In the sixth Fe site, Fe(6) is bonded to two equivalent Sm(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(5), and two equivalent Fe(7) atoms to form distorted FeSm2Fe10 cuboctahedra that share corners with two equivalent Fe(4)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(5)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(6)Sm2Fe10 cuboctahedra, corners with two equivalent Fe(1)Sm3Fe9 cuboctahedra, corners with four equivalent C(1)Sm2Fe4 octahedra,  an edgeedge with one Fe(6)Sm2Fe10 cuboctahedra, edges with two equivalent Fe(5)Sm2Fe10 cuboctahedra, edges with two equivalent C(1)Sm2Fe4 octahedra,  a faceface with one Fe(6)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(4)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(5)Sm2Fe10 cuboctahedra, and faces with four equivalent Fe(1)Sm3Fe9 cuboctahedra. The corner-sharing octahedral tilt angles range from 22-29°. In the seventh Fe site, Fe(7) is bonded in a single-bond geometry to one Fe(1), one Fe(4), one Fe(5), one Fe(6), two equivalent Fe(3), and one C(1) atom. C(1) is bonded to two equivalent Sm(1), two equivalent Fe(2), and two equivalent Fe(7) atoms to form CSm2Fe4 octahedra that share corners with two equivalent Fe(5)Sm2Fe10 cuboctahedra, corners with four equivalent Fe(6)Sm2Fe10 cuboctahedra, corners with four equivalent Fe(1)Sm3Fe9 cuboctahedra, corners with two equivalent C(1)Sm2Fe4 octahedra, edges with two equivalent Fe(6)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(4)Sm2Fe10 cuboctahedra, faces with two equivalent Fe(5)Sm2Fe10 cuboctahedra, and faces with two equivalent Fe(1)Sm3Fe9 cuboctahedra. The corner-sharing octahedral tilt angles are 63°. is represented by the CIF card [CIF]
data_Sm2Fe17C2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.492
_cell_length_b   6.492
_cell_length_c   6.501
_cell_angle_alpha   83.726
_cell_angle_beta   83.726
_cell_angle_gamma   83.677
_symmetry_Int_Tables_number   1
_cell_volume   269.399
_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  0.347  0.347  0.333  1.0
  Sm  Sm1  1  0.653  0.653  0.667  1.0
  Fe  Fe2  1  0.658  0.658  0.147  1.0
  Fe  Fe3  1  0.656  0.146  0.659  1.0
  Fe  Fe4  1  0.146  0.656  0.659  1.0
  Fe  Fe5  1  0.342  0.342  0.853  1.0
  Fe  Fe6  1  0.344  0.854  0.341  1.0
  Fe  Fe7  1  0.854  0.344  0.341  1.0
  Fe  Fe8  1  0.096  0.096  0.096  1.0
  Fe  Fe9  1  0.904  0.904  0.904  1.0
  Fe  Fe10  1  0.000  0.000  0.500  1.0
  Fe  Fe11  1  0.000  0.500  0.000  1.0
  Fe  Fe12  1  0.500  0.000  0.000  1.0
  Fe  Fe13  1  0.714  0.286  0.000  1.0
  Fe  Fe14  1  0.286  0.001  0.714  1.0
  Fe  Fe15  1  0.999  0.714  0.286  1.0
  Fe  Fe16  1  0.714  0.999  0.286  1.0
  Fe  Fe17  1  0.001  0.286  0.714  1.0
  Fe  Fe18  1  0.286  0.714  0.000  1.0
  C  C19  1  0.500  0.000  0.500  1.0
  C  C20  1  0.000  0.500  0.500  1.0
[/CIF]
.