La(ErS2)3 crystallizes in the monoclinic P2_1/m space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded to one S(2), one S(5), two equivalent S(4), and three equivalent S(3) atoms to form distorted ErS7 pentagonal bipyramids that share  a cornercorner with one Er(2)S6 octahedra, corners with two equivalent Er(3)S6 octahedra, edges with two equivalent Er(2)S6 octahedra, and edges with four equivalent Er(1)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-51°. In the second Er site, Er(2) is bonded to one S(3), two equivalent S(5), and three equivalent S(1) atoms to form ErS6 octahedra that share corners with three equivalent Er(3)S6 octahedra,  a cornercorner with one Er(1)S7 pentagonal bipyramid, edges with four equivalent Er(2)S6 octahedra, and edges with two equivalent Er(1)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 53-63°. In the third Er site, Er(3) is bonded to one S(1), two equivalent S(2), and three equivalent S(6) atoms to form ErS6 octahedra that share corners with three equivalent Er(2)S6 octahedra, corners with two equivalent Er(1)S7 pentagonal bipyramids, and edges with four equivalent Er(3)S6 octahedra. The corner-sharing octahedral tilt angles range from 53-63°. La(1) is bonded in a 8-coordinate geometry to one S(2), two equivalent S(5), two equivalent S(6), and three equivalent S(4) atoms. There are six inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Er(3) and three equivalent Er(2) atoms. In the second S site, S(2) is bonded to one Er(1), two equivalent Er(3), and one La(1) atom to form distorted SLaEr3 trigonal pyramids that share corners with two equivalent S(6)La2Er3 square pyramids, corners with three equivalent S(3)Er4 tetrahedra,  a cornercorner with one S(4)La3Er2 trigonal bipyramid, corners with three equivalent S(5)La2Er3 trigonal bipyramids, corners with two equivalent S(2)LaEr3 trigonal pyramids, edges with three equivalent S(6)La2Er3 square pyramids, and edges with two equivalent S(4)La3Er2 trigonal bipyramids. In the third S site, S(3) is bonded to one Er(2) and three equivalent Er(1) atoms to form distorted SEr4 tetrahedra that share corners with two equivalent S(3)Er4 tetrahedra,  a cornercorner with one S(5)La2Er3 trigonal bipyramid, corners with four equivalent S(4)La3Er2 trigonal bipyramids, corners with three equivalent S(2)LaEr3 trigonal pyramids, edges with two equivalent S(3)Er4 tetrahedra,  an edgeedge with one S(4)La3Er2 trigonal bipyramid, and edges with two equivalent S(5)La2Er3 trigonal bipyramids. In the fourth S site, S(4) is bonded to two equivalent Er(1) and three equivalent La(1) atoms to form distorted SLa3Er2 trigonal bipyramids that share corners with four equivalent S(6)La2Er3 square pyramids, corners with four equivalent S(3)Er4 tetrahedra, corners with two equivalent S(5)La2Er3 trigonal bipyramids,  a cornercorner with one S(2)LaEr3 trigonal pyramid,  an edgeedge with one S(6)La2Er3 square pyramid,  an edgeedge with one S(3)Er4 tetrahedra, edges with three equivalent S(5)La2Er3 trigonal bipyramids, edges with four equivalent S(4)La3Er2 trigonal bipyramids, and edges with two equivalent S(2)LaEr3 trigonal pyramids. In the fifth S site, S(5) is bonded to one Er(1), two equivalent Er(2), and two equivalent La(1) atoms to form distorted SLa2Er3 trigonal bipyramids that share corners with two equivalent S(6)La2Er3 square pyramids,  a cornercorner with one S(3)Er4 tetrahedra, corners with two equivalent S(4)La3Er2 trigonal bipyramids, corners with three equivalent S(2)LaEr3 trigonal pyramids,  an edgeedge with one S(6)La2Er3 square pyramid, edges with two equivalent S(3)Er4 tetrahedra, edges with two equivalent S(5)La2Er3 trigonal bipyramids, and edges with three equivalent S(4)La3Er2 trigonal bipyramids. In the sixth S site, S(6) is bonded to three equivalent Er(3) and two equivalent La(1) atoms to form SLa2Er3 square pyramids that share corners with two equivalent S(5)La2Er3 trigonal bipyramids, corners with four equivalent S(4)La3Er2 trigonal bipyramids, corners with two equivalent S(2)LaEr3 trigonal pyramids, edges with four equivalent S(6)La2Er3 square pyramids,  an edgeedge with one S(5)La2Er3 trigonal bipyramid,  an edgeedge with one S(4)La3Er2 trigonal bipyramid, and edges with three equivalent S(2)LaEr3 trigonal pyramids.
La(ErS2)3 crystallizes in the monoclinic P2_1/m space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded to one S(2), one S(5), two equivalent S(4), and three equivalent S(3) atoms to form distorted ErS7 pentagonal bipyramids that share  a cornercorner with one Er(2)S6 octahedra, corners with two equivalent Er(3)S6 octahedra, edges with two equivalent Er(2)S6 octahedra, and edges with four equivalent Er(1)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-51°. The Er(1)-S(2) bond length is 2.71 Å. The Er(1)-S(5) bond length is 2.84 Å. Both Er(1)-S(4) bond lengths are 2.90 Å. There are two shorter (2.67 Å) and one longer (2.87 Å) Er(1)-S(3) bond length. In the second Er site, Er(2) is bonded to one S(3), two equivalent S(5), and three equivalent S(1) atoms to form ErS6 octahedra that share corners with three equivalent Er(3)S6 octahedra,  a cornercorner with one Er(1)S7 pentagonal bipyramid, edges with four equivalent Er(2)S6 octahedra, and edges with two equivalent Er(1)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 53-63°. The Er(2)-S(3) bond length is 2.65 Å. Both Er(2)-S(5) bond lengths are 2.75 Å. There are two shorter (2.70 Å) and one longer (2.76 Å) Er(2)-S(1) bond length. In the third Er site, Er(3) is bonded to one S(1), two equivalent S(2), and three equivalent S(6) atoms to form ErS6 octahedra that share corners with three equivalent Er(2)S6 octahedra, corners with two equivalent Er(1)S7 pentagonal bipyramids, and edges with four equivalent Er(3)S6 octahedra. The corner-sharing octahedral tilt angles range from 53-63°. The Er(3)-S(1) bond length is 2.69 Å. Both Er(3)-S(2) bond lengths are 2.63 Å. There is one shorter (2.69 Å) and two longer (2.77 Å) Er(3)-S(6) bond lengths. La(1) is bonded in a 8-coordinate geometry to one S(2), two equivalent S(5), two equivalent S(6), and three equivalent S(4) atoms. The La(1)-S(2) bond length is 3.02 Å. Both La(1)-S(5) bond lengths are 3.06 Å. Both La(1)-S(6) bond lengths are 3.06 Å. There are two shorter (2.93 Å) and one longer (2.97 Å) La(1)-S(4) bond length. There are six inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Er(3) and three equivalent Er(2) atoms. In the second S site, S(2) is bonded to one Er(1), two equivalent Er(3), and one La(1) atom to form distorted SLaEr3 trigonal pyramids that share corners with two equivalent S(6)La2Er3 square pyramids, corners with three equivalent S(3)Er4 tetrahedra,  a cornercorner with one S(4)La3Er2 trigonal bipyramid, corners with three equivalent S(5)La2Er3 trigonal bipyramids, corners with two equivalent S(2)LaEr3 trigonal pyramids, edges with three equivalent S(6)La2Er3 square pyramids, and edges with two equivalent S(4)La3Er2 trigonal bipyramids. In the third S site, S(3) is bonded to one Er(2) and three equivalent Er(1) atoms to form distorted SEr4 tetrahedra that share corners with two equivalent S(3)Er4 tetrahedra,  a cornercorner with one S(5)La2Er3 trigonal bipyramid, corners with four equivalent S(4)La3Er2 trigonal bipyramids, corners with three equivalent S(2)LaEr3 trigonal pyramids, edges with two equivalent S(3)Er4 tetrahedra,  an edgeedge with one S(4)La3Er2 trigonal bipyramid, and edges with two equivalent S(5)La2Er3 trigonal bipyramids. In the fourth S site, S(4) is bonded to two equivalent Er(1) and three equivalent La(1) atoms to form distorted SLa3Er2 trigonal bipyramids that share corners with four equivalent S(6)La2Er3 square pyramids, corners with four equivalent S(3)Er4 tetrahedra, corners with two equivalent S(5)La2Er3 trigonal bipyramids,  a cornercorner with one S(2)LaEr3 trigonal pyramid,  an edgeedge with one S(6)La2Er3 square pyramid,  an edgeedge with one S(3)Er4 tetrahedra, edges with three equivalent S(5)La2Er3 trigonal bipyramids, edges with four equivalent S(4)La3Er2 trigonal bipyramids, and edges with two equivalent S(2)LaEr3 trigonal pyramids. In the fifth S site, S(5) is bonded to one Er(1), two equivalent Er(2), and two equivalent La(1) atoms to form distorted SLa2Er3 trigonal bipyramids that share corners with two equivalent S(6)La2Er3 square pyramids,  a cornercorner with one S(3)Er4 tetrahedra, corners with two equivalent S(4)La3Er2 trigonal bipyramids, corners with three equivalent S(2)LaEr3 trigonal pyramids,  an edgeedge with one S(6)La2Er3 square pyramid, edges with two equivalent S(3)Er4 tetrahedra, edges with two equivalent S(5)La2Er3 trigonal bipyramids, and edges with three equivalent S(4)La3Er2 trigonal bipyramids. In the sixth S site, S(6) is bonded to three equivalent Er(3) and two equivalent La(1) atoms to form SLa2Er3 square pyramids that share corners with two equivalent S(5)La2Er3 trigonal bipyramids, corners with four equivalent S(4)La3Er2 trigonal bipyramids, corners with two equivalent S(2)LaEr3 trigonal pyramids, edges with four equivalent S(6)La2Er3 square pyramids,  an edgeedge with one S(5)La2Er3 trigonal bipyramid,  an edgeedge with one S(4)La3Er2 trigonal bipyramid, and edges with three equivalent S(2)LaEr3 trigonal pyramids.