The compound described by Er4FeS7 crystallizes in the monoclinic Cm space group. There are four inequivalent Er sites. In the first Er site, Er(1) is bonded in a 7-coordinate geometry to one S(4), two equivalent S(1), two equivalent S(3), and two equivalent S(6) atoms. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one S(3), two equivalent S(2), two equivalent S(4), and two equivalent S(5) atoms. In the third Er site, Er(3) is bonded to one S(2), one S(6), two equivalent S(5), and two equivalent S(7) atoms to form ErS6 octahedra that share  a cornercorner with one Er(4)S6 octahedra, corners with two equivalent Fe(1)S6 octahedra, edges with two equivalent Er(3)S6 octahedra, and edges with three equivalent Fe(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 4-51°. In the fourth Er site, Er(4) is bonded to one S(1), one S(2), two equivalent S(3), and two equivalent S(4) atoms to form ErS6 octahedra that share  a cornercorner with one Er(3)S6 octahedra,  a cornercorner with one Fe(1)S6 octahedra, and edges with two equivalent Er(4)S6 octahedra. The corner-sharing octahedral tilt angles range from 51-53°. Fe(1) is bonded to one S(1), one S(5), two equivalent S(6), and two equivalent S(7) atoms to form FeS6 octahedra that share  a cornercorner with one Er(4)S6 octahedra, corners with two equivalent Er(3)S6 octahedra, edges with two equivalent Fe(1)S6 octahedra, and edges with three equivalent Er(3)S6 octahedra. The corner-sharing octahedral tilt angles range from 4-53°. There are seven inequivalent S sites. In the first S site, S(1) is bonded to one Er(4), two equivalent Er(1), and one Fe(1) atom to form distorted SEr3Fe tetrahedra that share  a cornercorner with one S(2)Er4 tetrahedra, corners with two equivalent S(1)Er3Fe tetrahedra,  a cornercorner with one S(5)Er4Fe trigonal bipyramid, corners with four equivalent S(6)Er3Fe2 trigonal bipyramids, corners with four equivalent S(3)Er5 trigonal bipyramids,  an edgeedge with one S(6)Er3Fe2 trigonal bipyramid,  an edgeedge with one S(3)Er5 trigonal bipyramid, and edges with two equivalent S(4)Er5 trigonal bipyramids. In the second S site, S(2) is bonded to one Er(3), one Er(4), and two equivalent Er(2) atoms to form SEr4 tetrahedra that share  a cornercorner with one S(1)Er3Fe tetrahedra, corners with two equivalent S(2)Er4 tetrahedra,  a cornercorner with one S(6)Er3Fe2 trigonal bipyramid, corners with four equivalent S(5)Er4Fe trigonal bipyramids, corners with four equivalent S(4)Er5 trigonal bipyramids,  an edgeedge with one S(5)Er4Fe trigonal bipyramid,  an edgeedge with one S(4)Er5 trigonal bipyramid, and edges with two equivalent S(3)Er5 trigonal bipyramids. In the third S site, S(3) is bonded to one Er(2), two equivalent Er(1), and two equivalent Er(4) atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent S(1)Er3Fe tetrahedra, corners with two equivalent S(6)Er3Fe2 trigonal bipyramids, corners with two equivalent S(5)Er4Fe trigonal bipyramids, corners with two equivalent S(4)Er5 trigonal bipyramids,  an edgeedge with one S(1)Er3Fe tetrahedra, edges with two equivalent S(2)Er4 tetrahedra,  an edgeedge with one S(6)Er3Fe2 trigonal bipyramid, edges with two equivalent S(3)Er5 trigonal bipyramids, and edges with three equivalent S(4)Er5 trigonal bipyramids. In the fourth S site, S(4) is bonded to one Er(1), two equivalent Er(2), and two equivalent Er(4) atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent S(2)Er4 tetrahedra, corners with two equivalent S(6)Er3Fe2 trigonal bipyramids, corners with two equivalent S(5)Er4Fe trigonal bipyramids, corners with two equivalent S(3)Er5 trigonal bipyramids,  an edgeedge with one S(2)Er4 tetrahedra, edges with two equivalent S(1)Er3Fe tetrahedra,  an edgeedge with one S(5)Er4Fe trigonal bipyramid, edges with two equivalent S(4)Er5 trigonal bipyramids, and edges with three equivalent S(3)Er5 trigonal bipyramids. In the fifth S site, S(5) is bonded to two equivalent Er(2), two equivalent Er(3), and one Fe(1) atom to form SEr4Fe trigonal bipyramids that share  a cornercorner with one S(1)Er3Fe tetrahedra, corners with four equivalent S(2)Er4 tetrahedra, corners with two equivalent S(3)Er5 trigonal bipyramids, corners with two equivalent S(4)Er5 trigonal bipyramids,  an edgeedge with one S(2)Er4 tetrahedra,  an edgeedge with one S(4)Er5 trigonal bipyramid, edges with two equivalent S(6)Er3Fe2 trigonal bipyramids, and edges with two equivalent S(5)Er4Fe trigonal bipyramids. In the sixth S site, S(6) is bonded to one Er(3), two equivalent Er(1), and two equivalent Fe(1) atoms to form SEr3Fe2 trigonal bipyramids that share  a cornercorner with one S(2)Er4 tetrahedra, corners with four equivalent S(1)Er3Fe tetrahedra, corners with two equivalent S(3)Er5 trigonal bipyramids, corners with two equivalent S(4)Er5 trigonal bipyramids,  an edgeedge with one S(1)Er3Fe tetrahedra,  an edgeedge with one S(3)Er5 trigonal bipyramid, edges with two equivalent S(6)Er3Fe2 trigonal bipyramids, and edges with two equivalent S(5)Er4Fe trigonal bipyramids. In the seventh S site, S(7) is bonded in a rectangular see-saw-like geometry to two equivalent Er(3) and two equivalent Fe(1) atoms. is represented by the CIF card [CIF]
data_Er4FeS7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.462
_cell_length_b   6.462
_cell_length_c   11.365
_cell_angle_alpha   76.209
_cell_angle_beta   76.209
_cell_angle_gamma   33.858
_symmetry_Int_Tables_number   1
_cell_volume   256.079
_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
  Er  Er0  1  0.695  0.695  0.206  1.0
  Er  Er1  1  0.305  0.305  0.802  1.0
  Er  Er2  1  0.112  0.112  0.565  1.0
  Er  Er3  1  0.999  0.999  0.006  1.0
  Fe  Fe4  1  0.889  0.889  0.423  1.0
  S  S5  1  0.033  0.033  0.227  1.0
  S  S6  1  0.963  0.963  0.784  1.0
  S  S7  1  0.338  0.338  0.052  1.0
  S  S8  1  0.660  0.660  0.949  1.0
  S  S9  1  0.745  0.745  0.639  1.0
  S  S10  1  0.269  0.269  0.354  1.0
  S  S11  1  0.491  0.491  0.494  1.0
[/CIF]
.
The compound described by Er4FeS7 crystallizes in the monoclinic Cm space group. There are four inequivalent Er sites. In the first Er site, Er(1) is bonded in a 7-coordinate geometry to one S(4), two equivalent S(1), two equivalent S(3), and two equivalent S(6) atoms. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one S(3), two equivalent S(2), two equivalent S(4), and two equivalent S(5) atoms. In the third Er site, Er(3) is bonded to one S(2), one S(6), two equivalent S(5), and two equivalent S(7) atoms to form ErS6 octahedra that share  a cornercorner with one Er(4)S6 octahedra, corners with two equivalent Fe(1)S6 octahedra, edges with two equivalent Er(3)S6 octahedra, and edges with three equivalent Fe(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 4-51°. In the fourth Er site, Er(4) is bonded to one S(1), one S(2), two equivalent S(3), and two equivalent S(4) atoms to form ErS6 octahedra that share  a cornercorner with one Er(3)S6 octahedra,  a cornercorner with one Fe(1)S6 octahedra, and edges with two equivalent Er(4)S6 octahedra. The corner-sharing octahedral tilt angles range from 51-53°. Fe(1) is bonded to one S(1), one S(5), two equivalent S(6), and two equivalent S(7) atoms to form FeS6 octahedra that share  a cornercorner with one Er(4)S6 octahedra, corners with two equivalent Er(3)S6 octahedra, edges with two equivalent Fe(1)S6 octahedra, and edges with three equivalent Er(3)S6 octahedra. The corner-sharing octahedral tilt angles range from 4-53°. There are seven inequivalent S sites. In the first S site, S(1) is bonded to one Er(4), two equivalent Er(1), and one Fe(1) atom to form distorted SEr3Fe tetrahedra that share  a cornercorner with one S(2)Er4 tetrahedra, corners with two equivalent S(1)Er3Fe tetrahedra,  a cornercorner with one S(5)Er4Fe trigonal bipyramid, corners with four equivalent S(6)Er3Fe2 trigonal bipyramids, corners with four equivalent S(3)Er5 trigonal bipyramids,  an edgeedge with one S(6)Er3Fe2 trigonal bipyramid,  an edgeedge with one S(3)Er5 trigonal bipyramid, and edges with two equivalent S(4)Er5 trigonal bipyramids. In the second S site, S(2) is bonded to one Er(3), one Er(4), and two equivalent Er(2) atoms to form SEr4 tetrahedra that share  a cornercorner with one S(1)Er3Fe tetrahedra, corners with two equivalent S(2)Er4 tetrahedra,  a cornercorner with one S(6)Er3Fe2 trigonal bipyramid, corners with four equivalent S(5)Er4Fe trigonal bipyramids, corners with four equivalent S(4)Er5 trigonal bipyramids,  an edgeedge with one S(5)Er4Fe trigonal bipyramid,  an edgeedge with one S(4)Er5 trigonal bipyramid, and edges with two equivalent S(3)Er5 trigonal bipyramids. In the third S site, S(3) is bonded to one Er(2), two equivalent Er(1), and two equivalent Er(4) atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent S(1)Er3Fe tetrahedra, corners with two equivalent S(6)Er3Fe2 trigonal bipyramids, corners with two equivalent S(5)Er4Fe trigonal bipyramids, corners with two equivalent S(4)Er5 trigonal bipyramids,  an edgeedge with one S(1)Er3Fe tetrahedra, edges with two equivalent S(2)Er4 tetrahedra,  an edgeedge with one S(6)Er3Fe2 trigonal bipyramid, edges with two equivalent S(3)Er5 trigonal bipyramids, and edges with three equivalent S(4)Er5 trigonal bipyramids. In the fourth S site, S(4) is bonded to one Er(1), two equivalent Er(2), and two equivalent Er(4) atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent S(2)Er4 tetrahedra, corners with two equivalent S(6)Er3Fe2 trigonal bipyramids, corners with two equivalent S(5)Er4Fe trigonal bipyramids, corners with two equivalent S(3)Er5 trigonal bipyramids,  an edgeedge with one S(2)Er4 tetrahedra, edges with two equivalent S(1)Er3Fe tetrahedra,  an edgeedge with one S(5)Er4Fe trigonal bipyramid, edges with two equivalent S(4)Er5 trigonal bipyramids, and edges with three equivalent S(3)Er5 trigonal bipyramids. In the fifth S site, S(5) is bonded to two equivalent Er(2), two equivalent Er(3), and one Fe(1) atom to form SEr4Fe trigonal bipyramids that share  a cornercorner with one S(1)Er3Fe tetrahedra, corners with four equivalent S(2)Er4 tetrahedra, corners with two equivalent S(3)Er5 trigonal bipyramids, corners with two equivalent S(4)Er5 trigonal bipyramids,  an edgeedge with one S(2)Er4 tetrahedra,  an edgeedge with one S(4)Er5 trigonal bipyramid, edges with two equivalent S(6)Er3Fe2 trigonal bipyramids, and edges with two equivalent S(5)Er4Fe trigonal bipyramids. In the sixth S site, S(6) is bonded to one Er(3), two equivalent Er(1), and two equivalent Fe(1) atoms to form SEr3Fe2 trigonal bipyramids that share  a cornercorner with one S(2)Er4 tetrahedra, corners with four equivalent S(1)Er3Fe tetrahedra, corners with two equivalent S(3)Er5 trigonal bipyramids, corners with two equivalent S(4)Er5 trigonal bipyramids,  an edgeedge with one S(1)Er3Fe tetrahedra,  an edgeedge with one S(3)Er5 trigonal bipyramid, edges with two equivalent S(6)Er3Fe2 trigonal bipyramids, and edges with two equivalent S(5)Er4Fe trigonal bipyramids. In the seventh S site, S(7) is bonded in a rectangular see-saw-like geometry to two equivalent Er(3) and two equivalent Fe(1) atoms. is represented by the CIF card [CIF]
data_Er4FeS7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.462
_cell_length_b   6.462
_cell_length_c   11.365
_cell_angle_alpha   76.209
_cell_angle_beta   76.209
_cell_angle_gamma   33.858
_symmetry_Int_Tables_number   1
_cell_volume   256.079
_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
  Er  Er0  1  0.695  0.695  0.206  1.0
  Er  Er1  1  0.305  0.305  0.802  1.0
  Er  Er2  1  0.112  0.112  0.565  1.0
  Er  Er3  1  0.999  0.999  0.006  1.0
  Fe  Fe4  1  0.889  0.889  0.423  1.0
  S  S5  1  0.033  0.033  0.227  1.0
  S  S6  1  0.963  0.963  0.784  1.0
  S  S7  1  0.338  0.338  0.052  1.0
  S  S8  1  0.660  0.660  0.949  1.0
  S  S9  1  0.745  0.745  0.639  1.0
  S  S10  1  0.269  0.269  0.354  1.0
  S  S11  1  0.491  0.491  0.494  1.0
[/CIF]
.