Er3CrS6 crystallizes in the orthorhombic Pnnm space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 8-coordinate geometry to one S(2), one S(3), two equivalent S(1), two equivalent S(4), and two equivalent S(5) atoms. In the second Er site, Er(2) is bonded to one S(2), one S(4), one S(6), two equivalent S(1), and two equivalent S(3) atoms to form distorted ErS7 pentagonal bipyramids that share  a cornercorner with one Cr(1)S6 octahedra, edges with two equivalent Cr(2)S6 octahedra, and edges with two equivalent Er(2)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 35°. In the third Er site, Er(3) is bonded in a 8-coordinate geometry to one S(2), one S(5), two equivalent S(3), two equivalent S(4), and two equivalent S(6) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent S(6) and four equivalent S(5) atoms to form CrS6 octahedra that share corners with two equivalent Er(2)S7 pentagonal bipyramids and edges with two equivalent Cr(1)S6 octahedra. In the second Cr site, Cr(2) is bonded to two equivalent S(1) and four equivalent S(2) atoms to form CrS6 octahedra that share edges with two equivalent Cr(2)S6 octahedra and edges with four equivalent Er(2)S7 pentagonal bipyramids. There are six inequivalent S sites. In the first S site, S(5) is bonded to one Er(3), two equivalent Er(1), and two equivalent Cr(1) atoms to form distorted SEr3Cr2 trigonal bipyramids that share corners with two equivalent S(1)Er4Cr square pyramids, corners with two equivalent S(5)Er3Cr2 trigonal bipyramids, corners with three equivalent S(2)Er3Cr2 trigonal bipyramids, corners with four equivalent S(4)Er5 trigonal bipyramids, corners with two equivalent S(6)Er3Cr trigonal pyramids,  an edgeedge with one S(1)Er4Cr square pyramid,  an edgeedge with one S(4)Er5 trigonal bipyramid, edges with two equivalent S(3)Er5 trigonal bipyramids, edges with three equivalent S(5)Er3Cr2 trigonal bipyramids, and edges with two equivalent S(6)Er3Cr trigonal pyramids. In the second S site, S(6) is bonded to one Er(2), two equivalent Er(3), and one Cr(1) atom to form distorted SEr3Cr trigonal pyramids that share corners with two equivalent S(1)Er4Cr square pyramids, corners with two equivalent S(5)Er3Cr2 trigonal bipyramids, corners with two equivalent S(4)Er5 trigonal bipyramids, corners with three equivalent S(2)Er3Cr2 trigonal bipyramids, corners with four equivalent S(3)Er5 trigonal bipyramids, corners with three equivalent S(6)Er3Cr trigonal pyramids,  an edgeedge with one S(3)Er5 trigonal bipyramid, edges with two equivalent S(5)Er3Cr2 trigonal bipyramids, and  a faceface with one S(4)Er5 trigonal bipyramid. In the third S site, S(1) is bonded to two equivalent Er(1), two equivalent Er(2), and one Cr(2) atom to form distorted SEr4Cr square pyramids that share  a cornercorner with one S(1)Er4Cr square pyramid, corners with two equivalent S(5)Er3Cr2 trigonal bipyramids, corners with four equivalent S(3)Er5 trigonal bipyramids, corners with four equivalent S(4)Er5 trigonal bipyramids, corners with two equivalent S(6)Er3Cr trigonal pyramids, edges with two equivalent S(1)Er4Cr square pyramids,  an edgeedge with one S(5)Er3Cr2 trigonal bipyramid,  an edgeedge with one S(3)Er5 trigonal bipyramid,  an edgeedge with one S(4)Er5 trigonal bipyramid, and edges with four equivalent S(2)Er3Cr2 trigonal bipyramids. In the fourth S site, S(2) is bonded to one Er(1), one Er(2), one Er(3), and two equivalent Cr(2) atoms to form distorted SEr3Cr2 trigonal bipyramids that share  a cornercorner with one S(3)Er5 trigonal bipyramid,  a cornercorner with one S(4)Er5 trigonal bipyramid, corners with three equivalent S(5)Er3Cr2 trigonal bipyramids, corners with four equivalent S(2)Er3Cr2 trigonal bipyramids, corners with three equivalent S(6)Er3Cr trigonal pyramids, edges with four equivalent S(1)Er4Cr square pyramids,  an edgeedge with one S(2)Er3Cr2 trigonal bipyramid, edges with two equivalent S(3)Er5 trigonal bipyramids, and edges with two equivalent S(4)Er5 trigonal bipyramids. In the fifth S site, S(3) is bonded to one Er(1), two equivalent Er(2), and two equivalent Er(3) atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent S(1)Er4Cr square pyramids,  a cornercorner with one S(2)Er3Cr2 trigonal bipyramid, corners with two equivalent S(4)Er5 trigonal bipyramids, corners with four equivalent S(6)Er3Cr trigonal pyramids,  an edgeedge with one S(1)Er4Cr square pyramid, edges with two equivalent S(2)Er3Cr2 trigonal bipyramids, edges with two equivalent S(5)Er3Cr2 trigonal bipyramids, edges with two equivalent S(3)Er5 trigonal bipyramids, edges with three equivalent S(4)Er5 trigonal bipyramids, and  an edgeedge with one S(6)Er3Cr trigonal pyramid. In the sixth S site, S(4) is bonded to one Er(2), two equivalent Er(1), and two equivalent Er(3) atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent S(1)Er4Cr square pyramids,  a cornercorner with one S(2)Er3Cr2 trigonal bipyramid, corners with two equivalent S(3)Er5 trigonal bipyramids, corners with four equivalent S(5)Er3Cr2 trigonal bipyramids, corners with two equivalent S(6)Er3Cr trigonal pyramids,  an edgeedge with one S(1)Er4Cr square pyramid,  an edgeedge with one S(5)Er3Cr2 trigonal bipyramid, edges with two equivalent S(2)Er3Cr2 trigonal bipyramids, edges with two equivalent S(4)Er5 trigonal bipyramids, edges with three equivalent S(3)Er5 trigonal bipyramids, and  a faceface with one S(6)Er3Cr trigonal pyramid.
Er3CrS6 crystallizes in the orthorhombic Pnnm space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 8-coordinate geometry to one S(2), one S(3), two equivalent S(1), two equivalent S(4), and two equivalent S(5) atoms. The Er(1)-S(2) bond length is 3.10 Å. The Er(1)-S(3) bond length is 2.98 Å. Both Er(1)-S(1) bond lengths are 2.83 Å. Both Er(1)-S(4) bond lengths are 2.71 Å. Both Er(1)-S(5) bond lengths are 2.84 Å. In the second Er site, Er(2) is bonded to one S(2), one S(4), one S(6), two equivalent S(1), and two equivalent S(3) atoms to form distorted ErS7 pentagonal bipyramids that share  a cornercorner with one Cr(1)S6 octahedra, edges with two equivalent Cr(2)S6 octahedra, and edges with two equivalent Er(2)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 35°. The Er(2)-S(2) bond length is 2.79 Å. The Er(2)-S(4) bond length is 2.83 Å. The Er(2)-S(6) bond length is 2.69 Å. Both Er(2)-S(1) bond lengths are 2.75 Å. Both Er(2)-S(3) bond lengths are 2.70 Å. In the third Er site, Er(3) is bonded in a 8-coordinate geometry to one S(2), one S(5), two equivalent S(3), two equivalent S(4), and two equivalent S(6) atoms. The Er(3)-S(2) bond length is 2.88 Å. The Er(3)-S(5) bond length is 2.89 Å. Both Er(3)-S(3) bond lengths are 2.78 Å. Both Er(3)-S(4) bond lengths are 2.83 Å. Both Er(3)-S(6) bond lengths are 2.73 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent S(6) and four equivalent S(5) atoms to form CrS6 octahedra that share corners with two equivalent Er(2)S7 pentagonal bipyramids and edges with two equivalent Cr(1)S6 octahedra. Both Cr(1)-S(6) bond lengths are 2.35 Å. All Cr(1)-S(5) bond lengths are 2.48 Å. In the second Cr site, Cr(2) is bonded to two equivalent S(1) and four equivalent S(2) atoms to form CrS6 octahedra that share edges with two equivalent Cr(2)S6 octahedra and edges with four equivalent Er(2)S7 pentagonal bipyramids. Both Cr(2)-S(1) bond lengths are 2.42 Å. All Cr(2)-S(2) bond lengths are 2.45 Å. There are six inequivalent S sites. In the first S site, S(5) is bonded to one Er(3), two equivalent Er(1), and two equivalent Cr(1) atoms to form distorted SEr3Cr2 trigonal bipyramids that share corners with two equivalent S(1)Er4Cr square pyramids, corners with two equivalent S(5)Er3Cr2 trigonal bipyramids, corners with three equivalent S(2)Er3Cr2 trigonal bipyramids, corners with four equivalent S(4)Er5 trigonal bipyramids, corners with two equivalent S(6)Er3Cr trigonal pyramids,  an edgeedge with one S(1)Er4Cr square pyramid,  an edgeedge with one S(4)Er5 trigonal bipyramid, edges with two equivalent S(3)Er5 trigonal bipyramids, edges with three equivalent S(5)Er3Cr2 trigonal bipyramids, and edges with two equivalent S(6)Er3Cr trigonal pyramids. In the second S site, S(6) is bonded to one Er(2), two equivalent Er(3), and one Cr(1) atom to form distorted SEr3Cr trigonal pyramids that share corners with two equivalent S(1)Er4Cr square pyramids, corners with two equivalent S(5)Er3Cr2 trigonal bipyramids, corners with two equivalent S(4)Er5 trigonal bipyramids, corners with three equivalent S(2)Er3Cr2 trigonal bipyramids, corners with four equivalent S(3)Er5 trigonal bipyramids, corners with three equivalent S(6)Er3Cr trigonal pyramids,  an edgeedge with one S(3)Er5 trigonal bipyramid, edges with two equivalent S(5)Er3Cr2 trigonal bipyramids, and  a faceface with one S(4)Er5 trigonal bipyramid. In the third S site, S(1) is bonded to two equivalent Er(1), two equivalent Er(2), and one Cr(2) atom to form distorted SEr4Cr square pyramids that share  a cornercorner with one S(1)Er4Cr square pyramid, corners with two equivalent S(5)Er3Cr2 trigonal bipyramids, corners with four equivalent S(3)Er5 trigonal bipyramids, corners with four equivalent S(4)Er5 trigonal bipyramids, corners with two equivalent S(6)Er3Cr trigonal pyramids, edges with two equivalent S(1)Er4Cr square pyramids,  an edgeedge with one S(5)Er3Cr2 trigonal bipyramid,  an edgeedge with one S(3)Er5 trigonal bipyramid,  an edgeedge with one S(4)Er5 trigonal bipyramid, and edges with four equivalent S(2)Er3Cr2 trigonal bipyramids. In the fourth S site, S(2) is bonded to one Er(1), one Er(2), one Er(3), and two equivalent Cr(2) atoms to form distorted SEr3Cr2 trigonal bipyramids that share  a cornercorner with one S(3)Er5 trigonal bipyramid,  a cornercorner with one S(4)Er5 trigonal bipyramid, corners with three equivalent S(5)Er3Cr2 trigonal bipyramids, corners with four equivalent S(2)Er3Cr2 trigonal bipyramids, corners with three equivalent S(6)Er3Cr trigonal pyramids, edges with four equivalent S(1)Er4Cr square pyramids,  an edgeedge with one S(2)Er3Cr2 trigonal bipyramid, edges with two equivalent S(3)Er5 trigonal bipyramids, and edges with two equivalent S(4)Er5 trigonal bipyramids. In the fifth S site, S(3) is bonded to one Er(1), two equivalent Er(2), and two equivalent Er(3) atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent S(1)Er4Cr square pyramids,  a cornercorner with one S(2)Er3Cr2 trigonal bipyramid, corners with two equivalent S(4)Er5 trigonal bipyramids, corners with four equivalent S(6)Er3Cr trigonal pyramids,  an edgeedge with one S(1)Er4Cr square pyramid, edges with two equivalent S(2)Er3Cr2 trigonal bipyramids, edges with two equivalent S(5)Er3Cr2 trigonal bipyramids, edges with two equivalent S(3)Er5 trigonal bipyramids, edges with three equivalent S(4)Er5 trigonal bipyramids, and  an edgeedge with one S(6)Er3Cr trigonal pyramid. In the sixth S site, S(4) is bonded to one Er(2), two equivalent Er(1), and two equivalent Er(3) atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent S(1)Er4Cr square pyramids,  a cornercorner with one S(2)Er3Cr2 trigonal bipyramid, corners with two equivalent S(3)Er5 trigonal bipyramids, corners with four equivalent S(5)Er3Cr2 trigonal bipyramids, corners with two equivalent S(6)Er3Cr trigonal pyramids,  an edgeedge with one S(1)Er4Cr square pyramid,  an edgeedge with one S(5)Er3Cr2 trigonal bipyramid, edges with two equivalent S(2)Er3Cr2 trigonal bipyramids, edges with two equivalent S(4)Er5 trigonal bipyramids, edges with three equivalent S(3)Er5 trigonal bipyramids, and  a faceface with one S(6)Er3Cr trigonal pyramid.