The material structure described by Sm2Fe15Si2C crystallizes in the monoclinic C2/m space group. Sm(1) is bonded in a distorted single-bond geometry to one Fe(5), two equivalent Fe(6), four equivalent Fe(4), six equivalent Fe(2), one Si(1), and one C(1) atom. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a single-bond geometry to two equivalent Fe(2), two equivalent Fe(4), two equivalent Fe(6), one Si(1), and one C(1) atom. In the second Fe site, Fe(2) is bonded to three equivalent Sm(1), one Fe(1), one Fe(2), one Fe(3), one Fe(5), one Fe(6), three equivalent Fe(4), and one Si(1) atom to form FeSm3Fe8Si cuboctahedra that share  a cornercorner with one Fe(5)Sm2Fe8Si2 cuboctahedra, corners with four equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, corners with five equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, corners with seven equivalent Fe(2)Sm3Fe8Si cuboctahedra, corners with two equivalent C(1)Sm2Fe4 octahedra,  an edgeedge with one Fe(4)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(5)Sm2Fe8Si2 cuboctahedra, edges with two equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, edges with three equivalent Fe(2)Sm3Fe8Si cuboctahedra,  a faceface with one Fe(5)Sm2Fe8Si2 cuboctahedra, faces with two equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, faces with four equivalent Fe(2)Sm3Fe8Si cuboctahedra, faces with seven equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, and  a faceface with one C(1)Sm2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 65-72°. In the third Fe site, Fe(3) is bonded in a single-bond geometry to two equivalent Fe(2), two equivalent Fe(4), two equivalent Fe(6), two equivalent Si(1), and one C(1) atom. In the fourth Fe site, Fe(4) is bonded to two equivalent Sm(1), one Fe(1), one Fe(3), one Fe(4), one Fe(5), one Fe(6), three equivalent Fe(2), and two equivalent Si(1) atoms to form distorted FeSm2Fe8Si2 cuboctahedra that share  a cornercorner with one Fe(5)Sm2Fe8Si2 cuboctahedra, corners with three equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, corners with five equivalent Fe(2)Sm3Fe8Si cuboctahedra, corners with seven equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, corners with two equivalent C(1)Sm2Fe4 octahedra,  an edgeedge with one Fe(4)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(5)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(6)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(2)Sm3Fe8Si cuboctahedra,  an edgeedge with one C(1)Sm2Fe4 octahedra,  a faceface with one Fe(5)Sm2Fe8Si2 cuboctahedra, faces with three equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, faces with four equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, and faces with seven equivalent Fe(2)Sm3Fe8Si cuboctahedra. The corner-sharing octahedral tilt angles range from 25-29°. In the fifth Fe site, Fe(5) is bonded to two equivalent Sm(1), four equivalent Fe(2), four equivalent Fe(4), and two equivalent Si(1) atoms to form distorted FeSm2Fe8Si2 cuboctahedra that share corners with four equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, corners with four equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, corners with four equivalent Fe(2)Sm3Fe8Si cuboctahedra, corners with two equivalent C(1)Sm2Fe4 octahedra, edges with four equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, edges with four equivalent Fe(2)Sm3Fe8Si cuboctahedra, faces with four equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, faces with four equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, and faces with four equivalent Fe(2)Sm3Fe8Si cuboctahedra. The corner-sharing octahedral tilt angles are 47°. 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(4), and two equivalent Si(1) atoms to form distorted FeSm2Fe8Si2 cuboctahedra that share corners with two equivalent Fe(5)Sm2Fe8Si2 cuboctahedra, corners with two equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, corners with six equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, corners with eight equivalent Fe(2)Sm3Fe8Si cuboctahedra, edges with two equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, edges with four equivalent Fe(2)Sm3Fe8Si cuboctahedra, faces with two equivalent Fe(5)Sm2Fe8Si2 cuboctahedra, faces with two equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, faces with four equivalent Fe(2)Sm3Fe8Si cuboctahedra, faces with six equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, and faces with two equivalent C(1)Sm2Fe4 octahedra. Si(1) is bonded in a 14-coordinate geometry to one Sm(1), one Fe(1), one Fe(5), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(6), four equivalent Fe(4), and one Si(1) atom. C(1) is bonded to two equivalent Sm(1), two equivalent Fe(1), and two equivalent Fe(3) atoms to form CSm2Fe4 octahedra that share corners with two equivalent Fe(5)Sm2Fe8Si2 cuboctahedra, corners with eight equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, corners with eight equivalent Fe(2)Sm3Fe8Si cuboctahedra, edges with four equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, faces with four equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, and faces with four equivalent Fe(2)Sm3Fe8Si cuboctahedra. is represented by the CIF file [CIF]
data_Sm2Fe15Si2C
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.471
_cell_length_b   6.471
_cell_length_c   6.475
_cell_angle_alpha   82.564
_cell_angle_beta   82.564
_cell_angle_gamma   82.281
_symmetry_Int_Tables_number   1
_cell_volume   264.663
_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  0.341  0.341  0.356  1.0
  Sm  Sm1  1  0.659  0.659  0.644  1.0
  Fe  Fe2  1  0.656  0.656  0.147  1.0
  Fe  Fe3  1  0.661  0.152  0.659  1.0
  Fe  Fe4  1  0.152  0.661  0.659  1.0
  Fe  Fe5  1  0.344  0.344  0.853  1.0
  Fe  Fe6  1  0.339  0.848  0.341  1.0
  Fe  Fe7  1  0.848  0.339  0.341  1.0
  Fe  Fe8  1  0.718  0.282  0.000  1.0
  Fe  Fe9  1  0.289  0.000  0.712  1.0
  Fe  Fe10  1  1.000  0.711  0.288  1.0
  Fe  Fe11  1  0.711  1.000  0.288  1.0
  Fe  Fe12  1  0.000  0.289  0.712  1.0
  Fe  Fe13  1  0.282  0.718  0.000  1.0
  Fe  Fe14  1  0.000  0.000  0.500  1.0
  Fe  Fe15  1  0.000  0.500  0.000  1.0
  Fe  Fe16  1  0.500  0.000  0.000  1.0
  Si  Si17  1  0.101  0.101  0.101  1.0
  Si  Si18  1  0.899  0.899  0.899  1.0
  C  C19  1  0.500  0.500  0.000  1.0
[/CIF]
.
The material structure described by Sm2Fe15Si2C crystallizes in the monoclinic C2/m space group. Sm(1) is bonded in a distorted single-bond geometry to one Fe(5), two equivalent Fe(6), four equivalent Fe(4), six equivalent Fe(2), one Si(1), and one C(1) atom. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a single-bond geometry to two equivalent Fe(2), two equivalent Fe(4), two equivalent Fe(6), one Si(1), and one C(1) atom. In the second Fe site, Fe(2) is bonded to three equivalent Sm(1), one Fe(1), one Fe(2), one Fe(3), one Fe(5), one Fe(6), three equivalent Fe(4), and one Si(1) atom to form FeSm3Fe8Si cuboctahedra that share  a cornercorner with one Fe(5)Sm2Fe8Si2 cuboctahedra, corners with four equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, corners with five equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, corners with seven equivalent Fe(2)Sm3Fe8Si cuboctahedra, corners with two equivalent C(1)Sm2Fe4 octahedra,  an edgeedge with one Fe(4)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(5)Sm2Fe8Si2 cuboctahedra, edges with two equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, edges with three equivalent Fe(2)Sm3Fe8Si cuboctahedra,  a faceface with one Fe(5)Sm2Fe8Si2 cuboctahedra, faces with two equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, faces with four equivalent Fe(2)Sm3Fe8Si cuboctahedra, faces with seven equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, and  a faceface with one C(1)Sm2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 65-72°. In the third Fe site, Fe(3) is bonded in a single-bond geometry to two equivalent Fe(2), two equivalent Fe(4), two equivalent Fe(6), two equivalent Si(1), and one C(1) atom. In the fourth Fe site, Fe(4) is bonded to two equivalent Sm(1), one Fe(1), one Fe(3), one Fe(4), one Fe(5), one Fe(6), three equivalent Fe(2), and two equivalent Si(1) atoms to form distorted FeSm2Fe8Si2 cuboctahedra that share  a cornercorner with one Fe(5)Sm2Fe8Si2 cuboctahedra, corners with three equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, corners with five equivalent Fe(2)Sm3Fe8Si cuboctahedra, corners with seven equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, corners with two equivalent C(1)Sm2Fe4 octahedra,  an edgeedge with one Fe(4)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(5)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(6)Sm2Fe8Si2 cuboctahedra,  an edgeedge with one Fe(2)Sm3Fe8Si cuboctahedra,  an edgeedge with one C(1)Sm2Fe4 octahedra,  a faceface with one Fe(5)Sm2Fe8Si2 cuboctahedra, faces with three equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, faces with four equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, and faces with seven equivalent Fe(2)Sm3Fe8Si cuboctahedra. The corner-sharing octahedral tilt angles range from 25-29°. In the fifth Fe site, Fe(5) is bonded to two equivalent Sm(1), four equivalent Fe(2), four equivalent Fe(4), and two equivalent Si(1) atoms to form distorted FeSm2Fe8Si2 cuboctahedra that share corners with four equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, corners with four equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, corners with four equivalent Fe(2)Sm3Fe8Si cuboctahedra, corners with two equivalent C(1)Sm2Fe4 octahedra, edges with four equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, edges with four equivalent Fe(2)Sm3Fe8Si cuboctahedra, faces with four equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, faces with four equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, and faces with four equivalent Fe(2)Sm3Fe8Si cuboctahedra. The corner-sharing octahedral tilt angles are 47°. 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(4), and two equivalent Si(1) atoms to form distorted FeSm2Fe8Si2 cuboctahedra that share corners with two equivalent Fe(5)Sm2Fe8Si2 cuboctahedra, corners with two equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, corners with six equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, corners with eight equivalent Fe(2)Sm3Fe8Si cuboctahedra, edges with two equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, edges with four equivalent Fe(2)Sm3Fe8Si cuboctahedra, faces with two equivalent Fe(5)Sm2Fe8Si2 cuboctahedra, faces with two equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, faces with four equivalent Fe(2)Sm3Fe8Si cuboctahedra, faces with six equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, and faces with two equivalent C(1)Sm2Fe4 octahedra. Si(1) is bonded in a 14-coordinate geometry to one Sm(1), one Fe(1), one Fe(5), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(6), four equivalent Fe(4), and one Si(1) atom. C(1) is bonded to two equivalent Sm(1), two equivalent Fe(1), and two equivalent Fe(3) atoms to form CSm2Fe4 octahedra that share corners with two equivalent Fe(5)Sm2Fe8Si2 cuboctahedra, corners with eight equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, corners with eight equivalent Fe(2)Sm3Fe8Si cuboctahedra, edges with four equivalent Fe(4)Sm2Fe8Si2 cuboctahedra, faces with four equivalent Fe(6)Sm2Fe8Si2 cuboctahedra, and faces with four equivalent Fe(2)Sm3Fe8Si cuboctahedra. is represented by the CIF file [CIF]
data_Sm2Fe15Si2C
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.471
_cell_length_b   6.471
_cell_length_c   6.475
_cell_angle_alpha   82.564
_cell_angle_beta   82.564
_cell_angle_gamma   82.281
_symmetry_Int_Tables_number   1
_cell_volume   264.663
_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  0.341  0.341  0.356  1.0
  Sm  Sm1  1  0.659  0.659  0.644  1.0
  Fe  Fe2  1  0.656  0.656  0.147  1.0
  Fe  Fe3  1  0.661  0.152  0.659  1.0
  Fe  Fe4  1  0.152  0.661  0.659  1.0
  Fe  Fe5  1  0.344  0.344  0.853  1.0
  Fe  Fe6  1  0.339  0.848  0.341  1.0
  Fe  Fe7  1  0.848  0.339  0.341  1.0
  Fe  Fe8  1  0.718  0.282  0.000  1.0
  Fe  Fe9  1  0.289  0.000  0.712  1.0
  Fe  Fe10  1  1.000  0.711  0.288  1.0
  Fe  Fe11  1  0.711  1.000  0.288  1.0
  Fe  Fe12  1  0.000  0.289  0.712  1.0
  Fe  Fe13  1  0.282  0.718  0.000  1.0
  Fe  Fe14  1  0.000  0.000  0.500  1.0
  Fe  Fe15  1  0.000  0.500  0.000  1.0
  Fe  Fe16  1  0.500  0.000  0.000  1.0
  Si  Si17  1  0.101  0.101  0.101  1.0
  Si  Si18  1  0.899  0.899  0.899  1.0
  C  C19  1  0.500  0.500  0.000  1.0
[/CIF]
.