The structure described by ErSmFe17C2 crystallizes in the monoclinic Cm space group. Er(1) is bonded in a distorted bent 120 degrees geometry to one Fe(1), one Fe(11), one Fe(7), two equivalent Fe(10), two equivalent Fe(5), two equivalent Fe(9), and two equivalent C(1) atoms. Sm(1) is bonded in a distorted bent 120 degrees geometry to one Fe(11), one Fe(2), one Fe(9), two equivalent Fe(10), two equivalent Fe(5), two equivalent Fe(7), and two equivalent C(1) atoms. There are eleven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 14-coordinate geometry to one Er(1), one Fe(11), one Fe(2), one Fe(9), two equivalent Fe(10), two equivalent Fe(3), two equivalent Fe(4), two equivalent Fe(5), and two equivalent Fe(8) atoms. In the second Fe site, Fe(2) is bonded in a 14-coordinate geometry to one Sm(1), one Fe(1), one Fe(11), one Fe(7), two equivalent Fe(10), two equivalent Fe(3), two equivalent Fe(4), two equivalent Fe(5), and two equivalent Fe(6) atoms. In the third Fe site, Fe(3) is bonded in a single-bond geometry to one Fe(1), one Fe(10), one Fe(11), one Fe(2), one Fe(5), one Fe(9), and one C(1) atom. In the fourth Fe site, Fe(4) is bonded in a single-bond geometry to one Fe(1), one Fe(10), one Fe(11), one Fe(2), one Fe(5), one Fe(7), and one C(1) atom. In the fifth Fe site, Fe(5) is bonded in a 12-coordinate geometry to one Er(1), one Sm(1), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(6), one Fe(7), one Fe(8), one Fe(9), and two equivalent Fe(10) atoms. In the sixth Fe site, Fe(6) is bonded in a single-bond geometry to one Fe(10), one Fe(11), one Fe(2), one Fe(5), one Fe(9), and one C(1) atom. In the seventh Fe site, Fe(7) is bonded to one Er(1), two equivalent Sm(1), one Fe(2), two equivalent Fe(10), two equivalent Fe(4), two equivalent Fe(5), and two equivalent Fe(8) atoms to form FeSm2ErFe9 cuboctahedra that share corners with two equivalent Fe(7)Sm2ErFe9 cuboctahedra, corners with two equivalent Fe(9)SmEr2Fe9 cuboctahedra, corners with two equivalent Fe(10)SmErFe10 cuboctahedra, corners with three equivalent Fe(11)SmErFe10 cuboctahedra, corners with four equivalent C(1)SmErFe4 octahedra,  an edgeedge with one Fe(9)SmEr2Fe9 cuboctahedra,  an edgeedge with one Fe(11)SmErFe10 cuboctahedra, edges with two equivalent Fe(10)SmErFe10 cuboctahedra,  a faceface with one Fe(9)SmEr2Fe9 cuboctahedra,  a faceface with one Fe(11)SmErFe10 cuboctahedra, faces with two equivalent Fe(10)SmErFe10 cuboctahedra, and faces with two equivalent C(1)SmErFe4 octahedra. The corner-sharing octahedral tilt angles range from 64-68°. In the eighth Fe site, Fe(8) is bonded in a single-bond geometry to one Fe(1), one Fe(10), one Fe(11), one Fe(5), one Fe(7), and one C(1) atom. In the ninth Fe site, Fe(9) is bonded to two equivalent Er(1), one Sm(1), one Fe(1), two equivalent Fe(10), two equivalent Fe(3), two equivalent Fe(5), and two equivalent Fe(6) atoms to form distorted FeSmEr2Fe9 cuboctahedra that share corners with two equivalent Fe(7)Sm2ErFe9 cuboctahedra, corners with two equivalent Fe(9)SmEr2Fe9 cuboctahedra, corners with two equivalent Fe(10)SmErFe10 cuboctahedra, corners with three equivalent Fe(11)SmErFe10 cuboctahedra, corners with four equivalent C(1)SmErFe4 octahedra,  an edgeedge with one Fe(7)Sm2ErFe9 cuboctahedra,  an edgeedge with one Fe(11)SmErFe10 cuboctahedra, edges with two equivalent Fe(10)SmErFe10 cuboctahedra,  a faceface with one Fe(7)Sm2ErFe9 cuboctahedra,  a faceface with one Fe(11)SmErFe10 cuboctahedra, faces with two equivalent Fe(10)SmErFe10 cuboctahedra, and faces with two equivalent C(1)SmErFe4 octahedra. The corner-sharing octahedral tilt angles range from 64-68°. In the tenth Fe site, Fe(10) is bonded to one Er(1), one Sm(1), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(6), one Fe(7), one Fe(8), one Fe(9), and two equivalent Fe(5) atoms to form FeSmErFe10 cuboctahedra that share  a cornercorner with one Fe(7)Sm2ErFe9 cuboctahedra,  a cornercorner with one Fe(9)SmEr2Fe9 cuboctahedra, corners with two equivalent Fe(10)SmErFe10 cuboctahedra, corners with two equivalent Fe(11)SmErFe10 cuboctahedra, corners with two equivalent C(1)SmErFe4 octahedra,  an edgeedge with one Fe(7)Sm2ErFe9 cuboctahedra,  an edgeedge with one Fe(9)SmEr2Fe9 cuboctahedra,  a faceface with one Fe(7)Sm2ErFe9 cuboctahedra,  a faceface with one Fe(9)SmEr2Fe9 cuboctahedra, faces with two equivalent Fe(10)SmErFe10 cuboctahedra, faces with two equivalent Fe(11)SmErFe10 cuboctahedra, and faces with two equivalent C(1)SmErFe4 octahedra. The corner-sharing octahedral tilt angles range from 43-44°. In the eleventh Fe site, Fe(11) is bonded to one Er(1), one Sm(1), one Fe(1), one Fe(2), two equivalent Fe(3), two equivalent Fe(4), two equivalent Fe(6), and two equivalent Fe(8) atoms to form distorted FeSmErFe10 cuboctahedra that share corners with three equivalent Fe(7)Sm2ErFe9 cuboctahedra, corners with three equivalent Fe(9)SmEr2Fe9 cuboctahedra, corners with four equivalent Fe(10)SmErFe10 cuboctahedra,  an edgeedge with one Fe(7)Sm2ErFe9 cuboctahedra,  an edgeedge with one Fe(9)SmEr2Fe9 cuboctahedra,  a faceface with one Fe(7)Sm2ErFe9 cuboctahedra,  a faceface with one Fe(9)SmEr2Fe9 cuboctahedra, faces with four equivalent Fe(10)SmErFe10 cuboctahedra, and faces with four equivalent C(1)SmErFe4 octahedra. C(1) is bonded to one Er(1), one Sm(1), one Fe(3), one Fe(4), one Fe(6), and one Fe(8) atom to form CSmErFe4 octahedra that share corners with two equivalent Fe(7)Sm2ErFe9 cuboctahedra, corners with two equivalent Fe(9)SmEr2Fe9 cuboctahedra, corners with two equivalent Fe(10)SmErFe10 cuboctahedra, corners with two equivalent C(1)SmErFe4 octahedra,  a faceface with one Fe(7)Sm2ErFe9 cuboctahedra,  a faceface with one Fe(9)SmEr2Fe9 cuboctahedra, faces with two equivalent Fe(10)SmErFe10 cuboctahedra, and faces with two equivalent Fe(11)SmErFe10 cuboctahedra. The corner-sharing octahedral tilt angles are 63°. is represented by the CIF file [CIF]
data_SmErFe17C2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.475
_cell_length_b   6.475
_cell_length_c   6.509
_cell_angle_alpha   83.552
_cell_angle_beta   83.552
_cell_angle_gamma   82.970
_symmetry_Int_Tables_number   1
_cell_volume   267.797
_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  0.345  0.345  0.333  1.0
  Er  Er1  1  0.657  0.657  0.669  1.0
  Fe  Fe2  1  0.904  0.904  0.903  1.0
  Fe  Fe3  1  0.094  0.094  0.095  1.0
  Fe  Fe4  1  0.715  0.999  0.285  1.0
  Fe  Fe5  1  0.999  0.286  0.716  1.0
  Fe  Fe6  1  0.292  0.709  0.998  1.0
  Fe  Fe7  1  0.999  0.715  0.285  1.0
  Fe  Fe8  1  0.709  0.292  0.998  1.0
  Fe  Fe9  1  0.286  0.999  0.716  1.0
  Fe  Fe10  1  0.346  0.851  0.343  1.0
  Fe  Fe11  1  0.851  0.346  0.343  1.0
  Fe  Fe12  1  0.344  0.344  0.849  1.0
  Fe  Fe13  1  0.656  0.147  0.658  1.0
  Fe  Fe14  1  0.147  0.656  0.658  1.0
  Fe  Fe15  1  0.657  0.657  0.148  1.0
  Fe  Fe16  1  1.000  0.500  0.999  1.0
  Fe  Fe17  1  0.500  1.000  0.999  1.0
  Fe  Fe18  1  0.000  0.000  0.500  1.0
  C  C19  1  0.503  0.994  0.502  1.0
  C  C20  1  0.994  0.503  0.502  1.0
[/CIF]
.
The structure described by ErSmFe17C2 crystallizes in the monoclinic Cm space group. Er(1) is bonded in a distorted bent 120 degrees geometry to one Fe(1), one Fe(11), one Fe(7), two equivalent Fe(10), two equivalent Fe(5), two equivalent Fe(9), and two equivalent C(1) atoms. Sm(1) is bonded in a distorted bent 120 degrees geometry to one Fe(11), one Fe(2), one Fe(9), two equivalent Fe(10), two equivalent Fe(5), two equivalent Fe(7), and two equivalent C(1) atoms. There are eleven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 14-coordinate geometry to one Er(1), one Fe(11), one Fe(2), one Fe(9), two equivalent Fe(10), two equivalent Fe(3), two equivalent Fe(4), two equivalent Fe(5), and two equivalent Fe(8) atoms. In the second Fe site, Fe(2) is bonded in a 14-coordinate geometry to one Sm(1), one Fe(1), one Fe(11), one Fe(7), two equivalent Fe(10), two equivalent Fe(3), two equivalent Fe(4), two equivalent Fe(5), and two equivalent Fe(6) atoms. In the third Fe site, Fe(3) is bonded in a single-bond geometry to one Fe(1), one Fe(10), one Fe(11), one Fe(2), one Fe(5), one Fe(9), and one C(1) atom. In the fourth Fe site, Fe(4) is bonded in a single-bond geometry to one Fe(1), one Fe(10), one Fe(11), one Fe(2), one Fe(5), one Fe(7), and one C(1) atom. In the fifth Fe site, Fe(5) is bonded in a 12-coordinate geometry to one Er(1), one Sm(1), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(6), one Fe(7), one Fe(8), one Fe(9), and two equivalent Fe(10) atoms. In the sixth Fe site, Fe(6) is bonded in a single-bond geometry to one Fe(10), one Fe(11), one Fe(2), one Fe(5), one Fe(9), and one C(1) atom. In the seventh Fe site, Fe(7) is bonded to one Er(1), two equivalent Sm(1), one Fe(2), two equivalent Fe(10), two equivalent Fe(4), two equivalent Fe(5), and two equivalent Fe(8) atoms to form FeSm2ErFe9 cuboctahedra that share corners with two equivalent Fe(7)Sm2ErFe9 cuboctahedra, corners with two equivalent Fe(9)SmEr2Fe9 cuboctahedra, corners with two equivalent Fe(10)SmErFe10 cuboctahedra, corners with three equivalent Fe(11)SmErFe10 cuboctahedra, corners with four equivalent C(1)SmErFe4 octahedra,  an edgeedge with one Fe(9)SmEr2Fe9 cuboctahedra,  an edgeedge with one Fe(11)SmErFe10 cuboctahedra, edges with two equivalent Fe(10)SmErFe10 cuboctahedra,  a faceface with one Fe(9)SmEr2Fe9 cuboctahedra,  a faceface with one Fe(11)SmErFe10 cuboctahedra, faces with two equivalent Fe(10)SmErFe10 cuboctahedra, and faces with two equivalent C(1)SmErFe4 octahedra. The corner-sharing octahedral tilt angles range from 64-68°. In the eighth Fe site, Fe(8) is bonded in a single-bond geometry to one Fe(1), one Fe(10), one Fe(11), one Fe(5), one Fe(7), and one C(1) atom. In the ninth Fe site, Fe(9) is bonded to two equivalent Er(1), one Sm(1), one Fe(1), two equivalent Fe(10), two equivalent Fe(3), two equivalent Fe(5), and two equivalent Fe(6) atoms to form distorted FeSmEr2Fe9 cuboctahedra that share corners with two equivalent Fe(7)Sm2ErFe9 cuboctahedra, corners with two equivalent Fe(9)SmEr2Fe9 cuboctahedra, corners with two equivalent Fe(10)SmErFe10 cuboctahedra, corners with three equivalent Fe(11)SmErFe10 cuboctahedra, corners with four equivalent C(1)SmErFe4 octahedra,  an edgeedge with one Fe(7)Sm2ErFe9 cuboctahedra,  an edgeedge with one Fe(11)SmErFe10 cuboctahedra, edges with two equivalent Fe(10)SmErFe10 cuboctahedra,  a faceface with one Fe(7)Sm2ErFe9 cuboctahedra,  a faceface with one Fe(11)SmErFe10 cuboctahedra, faces with two equivalent Fe(10)SmErFe10 cuboctahedra, and faces with two equivalent C(1)SmErFe4 octahedra. The corner-sharing octahedral tilt angles range from 64-68°. In the tenth Fe site, Fe(10) is bonded to one Er(1), one Sm(1), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(6), one Fe(7), one Fe(8), one Fe(9), and two equivalent Fe(5) atoms to form FeSmErFe10 cuboctahedra that share  a cornercorner with one Fe(7)Sm2ErFe9 cuboctahedra,  a cornercorner with one Fe(9)SmEr2Fe9 cuboctahedra, corners with two equivalent Fe(10)SmErFe10 cuboctahedra, corners with two equivalent Fe(11)SmErFe10 cuboctahedra, corners with two equivalent C(1)SmErFe4 octahedra,  an edgeedge with one Fe(7)Sm2ErFe9 cuboctahedra,  an edgeedge with one Fe(9)SmEr2Fe9 cuboctahedra,  a faceface with one Fe(7)Sm2ErFe9 cuboctahedra,  a faceface with one Fe(9)SmEr2Fe9 cuboctahedra, faces with two equivalent Fe(10)SmErFe10 cuboctahedra, faces with two equivalent Fe(11)SmErFe10 cuboctahedra, and faces with two equivalent C(1)SmErFe4 octahedra. The corner-sharing octahedral tilt angles range from 43-44°. In the eleventh Fe site, Fe(11) is bonded to one Er(1), one Sm(1), one Fe(1), one Fe(2), two equivalent Fe(3), two equivalent Fe(4), two equivalent Fe(6), and two equivalent Fe(8) atoms to form distorted FeSmErFe10 cuboctahedra that share corners with three equivalent Fe(7)Sm2ErFe9 cuboctahedra, corners with three equivalent Fe(9)SmEr2Fe9 cuboctahedra, corners with four equivalent Fe(10)SmErFe10 cuboctahedra,  an edgeedge with one Fe(7)Sm2ErFe9 cuboctahedra,  an edgeedge with one Fe(9)SmEr2Fe9 cuboctahedra,  a faceface with one Fe(7)Sm2ErFe9 cuboctahedra,  a faceface with one Fe(9)SmEr2Fe9 cuboctahedra, faces with four equivalent Fe(10)SmErFe10 cuboctahedra, and faces with four equivalent C(1)SmErFe4 octahedra. C(1) is bonded to one Er(1), one Sm(1), one Fe(3), one Fe(4), one Fe(6), and one Fe(8) atom to form CSmErFe4 octahedra that share corners with two equivalent Fe(7)Sm2ErFe9 cuboctahedra, corners with two equivalent Fe(9)SmEr2Fe9 cuboctahedra, corners with two equivalent Fe(10)SmErFe10 cuboctahedra, corners with two equivalent C(1)SmErFe4 octahedra,  a faceface with one Fe(7)Sm2ErFe9 cuboctahedra,  a faceface with one Fe(9)SmEr2Fe9 cuboctahedra, faces with two equivalent Fe(10)SmErFe10 cuboctahedra, and faces with two equivalent Fe(11)SmErFe10 cuboctahedra. The corner-sharing octahedral tilt angles are 63°. is represented by the CIF file [CIF]
data_SmErFe17C2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.475
_cell_length_b   6.475
_cell_length_c   6.509
_cell_angle_alpha   83.552
_cell_angle_beta   83.552
_cell_angle_gamma   82.970
_symmetry_Int_Tables_number   1
_cell_volume   267.797
_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  0.345  0.345  0.333  1.0
  Er  Er1  1  0.657  0.657  0.669  1.0
  Fe  Fe2  1  0.904  0.904  0.903  1.0
  Fe  Fe3  1  0.094  0.094  0.095  1.0
  Fe  Fe4  1  0.715  0.999  0.285  1.0
  Fe  Fe5  1  0.999  0.286  0.716  1.0
  Fe  Fe6  1  0.292  0.709  0.998  1.0
  Fe  Fe7  1  0.999  0.715  0.285  1.0
  Fe  Fe8  1  0.709  0.292  0.998  1.0
  Fe  Fe9  1  0.286  0.999  0.716  1.0
  Fe  Fe10  1  0.346  0.851  0.343  1.0
  Fe  Fe11  1  0.851  0.346  0.343  1.0
  Fe  Fe12  1  0.344  0.344  0.849  1.0
  Fe  Fe13  1  0.656  0.147  0.658  1.0
  Fe  Fe14  1  0.147  0.656  0.658  1.0
  Fe  Fe15  1  0.657  0.657  0.148  1.0
  Fe  Fe16  1  1.000  0.500  0.999  1.0
  Fe  Fe17  1  0.500  1.000  0.999  1.0
  Fe  Fe18  1  0.000  0.000  0.500  1.0
  C  C19  1  0.503  0.994  0.502  1.0
  C  C20  1  0.994  0.503  0.502  1.0
[/CIF]
.