Rb3Er7S12 crystallizes in the orthorhombic Pmn2_1 space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to one S(12), two equivalent S(5), two equivalent S(7), and two equivalent S(9) atoms. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one S(11), two equivalent S(10), two equivalent S(6), and two equivalent S(8) atoms. In the third Rb site, Rb(3) is bonded in a 6-coordinate geometry to one S(10), one S(6), two equivalent S(1), and two equivalent S(2) atoms. There are seven inequivalent Er sites. In the first Er site, Er(1) is bonded to one S(11), one S(9), two equivalent S(3), and two equivalent S(8) atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedral tilt angles range from 3-14°. In the second Er site, Er(2) is bonded to one S(10), one S(12), two equivalent S(4), and two equivalent S(7) atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedral tilt angles range from 2-13°. In the third Er site, Er(3) is bonded to one S(1), one S(7), two equivalent S(10), and two equivalent S(3) atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedral tilt angles are 3°. In the fourth Er site, Er(4) is bonded to one S(2), one S(8), two equivalent S(4), and two equivalent S(9) atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedral tilt angles are 2°. In the fifth Er site, Er(5) is bonded to one S(3), one S(5), two equivalent S(1), and two equivalent S(11) atoms to form edge-sharing ErS6 octahedra. In the sixth Er site, Er(6) is bonded to one S(4), one S(6), two equivalent S(12), and two equivalent S(2) atoms to form edge-sharing ErS6 octahedra. In the seventh Er site, Er(7) is bonded to one S(11), one S(12), two equivalent S(5), and two equivalent S(6) atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedral tilt angles range from 13-14°. There are twelve inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Rb(3), one Er(3), and two equivalent Er(5) atoms to form distorted SRb2Er3 square pyramids that share  a cornercorner with one S(7)Rb2Er3 trigonal bipyramid, corners with two equivalent S(5)Rb2Er3 trigonal bipyramids, corners with two equivalent S(11)RbEr4 trigonal bipyramids, edges with two equivalent S(3)Er5 square pyramids, edges with two equivalent S(1)Rb2Er3 square pyramids, and  an edgeedge with one S(11)RbEr4 trigonal bipyramid. In the second S site, S(2) is bonded in a 5-coordinate geometry to two equivalent Rb(3), one Er(4), and two equivalent Er(6) atoms. In the third S site, S(3) is bonded to one Er(5), two equivalent Er(1), and two equivalent Er(3) atoms to form SEr5 square pyramids that share  a cornercorner with one S(5)Rb2Er3 trigonal bipyramid, corners with two equivalent S(7)Rb2Er3 trigonal bipyramids, corners with two equivalent S(8)Rb2Er3 trigonal bipyramids, corners with two equivalent S(9)Rb2Er3 trigonal bipyramids, edges with two equivalent S(3)Er5 square pyramids, edges with two equivalent S(1)Rb2Er3 square pyramids,  an edgeedge with one S(8)Rb2Er3 trigonal bipyramid, and edges with two equivalent S(11)RbEr4 trigonal bipyramids. In the fourth S site, S(4) is bonded to one Er(6), two equivalent Er(2), and two equivalent Er(4) atoms to form SEr5 square pyramids that share corners with two equivalent S(7)Rb2Er3 trigonal bipyramids, corners with two equivalent S(8)Rb2Er3 trigonal bipyramids, corners with two equivalent S(9)Rb2Er3 trigonal bipyramids, edges with two equivalent S(4)Er5 square pyramids,  an edgeedge with one S(7)Rb2Er3 trigonal bipyramid,  an edgeedge with one S(9)Rb2Er3 trigonal bipyramid, and edges with two equivalent S(12)RbEr4 trigonal bipyramids. In the fifth S site, S(5) is bonded to two equivalent Rb(1), one Er(5), and two equivalent Er(7) atoms to form distorted SRb2Er3 trigonal bipyramids that share  a cornercorner with one S(3)Er5 square pyramid, corners with two equivalent S(1)Rb2Er3 square pyramids, corners with two equivalent S(7)Rb2Er3 trigonal bipyramids, corners with two equivalent S(9)Rb2Er3 trigonal bipyramids,  an edgeedge with one S(7)Rb2Er3 trigonal bipyramid,  an edgeedge with one S(9)Rb2Er3 trigonal bipyramid, edges with two equivalent S(5)Rb2Er3 trigonal bipyramids, edges with two equivalent S(11)RbEr4 trigonal bipyramids, and edges with two equivalent S(12)RbEr4 trigonal bipyramids. In the sixth S site, S(6) is bonded in a 6-coordinate geometry to one Rb(3), two equivalent Rb(2), one Er(6), and two equivalent Er(7) atoms. In the seventh S site, S(7) is bonded to two equivalent Rb(1), one Er(3), and two equivalent Er(2) atoms to form distorted SRb2Er3 trigonal bipyramids that share  a cornercorner with one S(1)Rb2Er3 square pyramid, corners with two equivalent S(3)Er5 square pyramids, corners with two equivalent S(4)Er5 square pyramids, corners with two equivalent S(5)Rb2Er3 trigonal bipyramids, corners with two equivalent S(9)Rb2Er3 trigonal bipyramids,  an edgeedge with one S(4)Er5 square pyramid,  an edgeedge with one S(5)Rb2Er3 trigonal bipyramid,  an edgeedge with one S(9)Rb2Er3 trigonal bipyramid, edges with two equivalent S(7)Rb2Er3 trigonal bipyramids, and edges with two equivalent S(12)RbEr4 trigonal bipyramids. In the eighth S site, S(8) is bonded to two equivalent Rb(2), one Er(4), and two equivalent Er(1) atoms to form distorted SRb2Er3 trigonal bipyramids that share corners with two equivalent S(3)Er5 square pyramids, corners with two equivalent S(4)Er5 square pyramids,  an edgeedge with one S(3)Er5 square pyramid, edges with two equivalent S(8)Rb2Er3 trigonal bipyramids, edges with two equivalent S(9)Rb2Er3 trigonal bipyramids, and edges with two equivalent S(11)RbEr4 trigonal bipyramids. In the ninth S site, S(9) is bonded to two equivalent Rb(1), one Er(1), and two equivalent Er(4) atoms to form distorted SRb2Er3 trigonal bipyramids that share corners with two equivalent S(3)Er5 square pyramids, corners with two equivalent S(4)Er5 square pyramids,  a cornercorner with one S(11)RbEr4 trigonal bipyramid, corners with two equivalent S(5)Rb2Er3 trigonal bipyramids, corners with two equivalent S(7)Rb2Er3 trigonal bipyramids, corners with two equivalent S(12)RbEr4 trigonal bipyramids,  an edgeedge with one S(4)Er5 square pyramid,  an edgeedge with one S(5)Rb2Er3 trigonal bipyramid,  an edgeedge with one S(7)Rb2Er3 trigonal bipyramid, edges with two equivalent S(8)Rb2Er3 trigonal bipyramids, and edges with two equivalent S(9)Rb2Er3 trigonal bipyramids. In the tenth S site, S(10) is bonded in a 6-coordinate geometry to one Rb(3), two equivalent Rb(2), one Er(2), and two equivalent Er(3) atoms. In the eleventh S site, S(11) is bonded to one Rb(2), one Er(1), one Er(7), and two equivalent Er(5) atoms to form distorted SRbEr4 trigonal bipyramids that share corners with two equivalent S(1)Rb2Er3 square pyramids,  a cornercorner with one S(9)Rb2Er3 trigonal bipyramid,  a cornercorner with one S(12)RbEr4 trigonal bipyramid, corners with two equivalent S(11)RbEr4 trigonal bipyramids,  an edgeedge with one S(1)Rb2Er3 square pyramid, edges with two equivalent S(3)Er5 square pyramids, edges with two equivalent S(5)Rb2Er3 trigonal bipyramids, and edges with two equivalent S(8)Rb2Er3 trigonal bipyramids. In the twelfth S site, S(12) is bonded to one Rb(1), one Er(2), one Er(7), and two equivalent Er(6) atoms to form distorted SRbEr4 trigonal bipyramids that share  a cornercorner with one S(11)RbEr4 trigonal bipyramid, corners with two equivalent S(9)Rb2Er3 trigonal bipyramids, corners with two equivalent S(12)RbEr4 trigonal bipyramids, edges with two equivalent S(4)Er5 square pyramids, edges with two equivalent S(5)Rb2Er3 trigonal bipyramids, and edges with two equivalent S(7)Rb2Er3 trigonal bipyramids.
Rb3Er7S12 crystallizes in the orthorhombic Pmn2_1 space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 7-coordinate geometry to one S(12), two equivalent S(5), two equivalent S(7), and two equivalent S(9) atoms. The Rb(1)-S(12) bond length is 3.52 Å. Both Rb(1)-S(5) bond lengths are 3.49 Å. Both Rb(1)-S(7) bond lengths are 3.44 Å. Both Rb(1)-S(9) bond lengths are 3.45 Å. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one S(11), two equivalent S(10), two equivalent S(6), and two equivalent S(8) atoms. The Rb(2)-S(11) bond length is 3.45 Å. Both Rb(2)-S(10) bond lengths are 3.45 Å. Both Rb(2)-S(6) bond lengths are 3.58 Å. Both Rb(2)-S(8) bond lengths are 3.30 Å. In the third Rb site, Rb(3) is bonded in a 6-coordinate geometry to one S(10), one S(6), two equivalent S(1), and two equivalent S(2) atoms. The Rb(3)-S(10) bond length is 3.84 Å. The Rb(3)-S(6) bond length is 3.45 Å. Both Rb(3)-S(1) bond lengths are 3.23 Å. Both Rb(3)-S(2) bond lengths are 3.35 Å. There are seven inequivalent Er sites. In the first Er site, Er(1) is bonded to one S(11), one S(9), two equivalent S(3), and two equivalent S(8) atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedral tilt angles range from 3-14°. The Er(1)-S(11) bond length is 2.71 Å. The Er(1)-S(9) bond length is 2.70 Å. Both Er(1)-S(3) bond lengths are 2.81 Å. Both Er(1)-S(8) bond lengths are 2.64 Å. In the second Er site, Er(2) is bonded to one S(10), one S(12), two equivalent S(4), and two equivalent S(7) atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedral tilt angles range from 2-13°. The Er(2)-S(10) bond length is 2.75 Å. The Er(2)-S(12) bond length is 2.70 Å. Both Er(2)-S(4) bond lengths are 2.82 Å. Both Er(2)-S(7) bond lengths are 2.64 Å. In the third Er site, Er(3) is bonded to one S(1), one S(7), two equivalent S(10), and two equivalent S(3) atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedral tilt angles are 3°. The Er(3)-S(1) bond length is 2.69 Å. The Er(3)-S(7) bond length is 2.65 Å. Both Er(3)-S(10) bond lengths are 2.68 Å. Both Er(3)-S(3) bond lengths are 2.83 Å. In the fourth Er site, Er(4) is bonded to one S(2), one S(8), two equivalent S(4), and two equivalent S(9) atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedral tilt angles are 2°. The Er(4)-S(2) bond length is 2.67 Å. The Er(4)-S(8) bond length is 2.65 Å. Both Er(4)-S(4) bond lengths are 2.87 Å. Both Er(4)-S(9) bond lengths are 2.66 Å. In the fifth Er site, Er(5) is bonded to one S(3), one S(5), two equivalent S(1), and two equivalent S(11) atoms to form edge-sharing ErS6 octahedra. The Er(5)-S(3) bond length is 2.85 Å. The Er(5)-S(5) bond length is 2.63 Å. Both Er(5)-S(1) bond lengths are 2.69 Å. Both Er(5)-S(11) bond lengths are 2.72 Å. In the sixth Er site, Er(6) is bonded to one S(4), one S(6), two equivalent S(12), and two equivalent S(2) atoms to form edge-sharing ErS6 octahedra. The Er(6)-S(4) bond length is 2.80 Å. The Er(6)-S(6) bond length is 2.67 Å. Both Er(6)-S(12) bond lengths are 2.71 Å. Both Er(6)-S(2) bond lengths are 2.70 Å. In the seventh Er site, Er(7) is bonded to one S(11), one S(12), two equivalent S(5), and two equivalent S(6) atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedral tilt angles range from 13-14°. The Er(7)-S(11) bond length is 2.69 Å. The Er(7)-S(12) bond length is 2.70 Å. Both Er(7)-S(5) bond lengths are 2.71 Å. Both Er(7)-S(6) bond lengths are 2.75 Å. There are twelve inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Rb(3), one Er(3), and two equivalent Er(5) atoms to form distorted SRb2Er3 square pyramids that share  a cornercorner with one S(7)Rb2Er3 trigonal bipyramid, corners with two equivalent S(5)Rb2Er3 trigonal bipyramids, corners with two equivalent S(11)RbEr4 trigonal bipyramids, edges with two equivalent S(3)Er5 square pyramids, edges with two equivalent S(1)Rb2Er3 square pyramids, and  an edgeedge with one S(11)RbEr4 trigonal bipyramid. In the second S site, S(2) is bonded in a 5-coordinate geometry to two equivalent Rb(3), one Er(4), and two equivalent Er(6) atoms. In the third S site, S(3) is bonded to one Er(5), two equivalent Er(1), and two equivalent Er(3) atoms to form SEr5 square pyramids that share  a cornercorner with one S(5)Rb2Er3 trigonal bipyramid, corners with two equivalent S(7)Rb2Er3 trigonal bipyramids, corners with two equivalent S(8)Rb2Er3 trigonal bipyramids, corners with two equivalent S(9)Rb2Er3 trigonal bipyramids, edges with two equivalent S(3)Er5 square pyramids, edges with two equivalent S(1)Rb2Er3 square pyramids,  an edgeedge with one S(8)Rb2Er3 trigonal bipyramid, and edges with two equivalent S(11)RbEr4 trigonal bipyramids. In the fourth S site, S(4) is bonded to one Er(6), two equivalent Er(2), and two equivalent Er(4) atoms to form SEr5 square pyramids that share corners with two equivalent S(7)Rb2Er3 trigonal bipyramids, corners with two equivalent S(8)Rb2Er3 trigonal bipyramids, corners with two equivalent S(9)Rb2Er3 trigonal bipyramids, edges with two equivalent S(4)Er5 square pyramids,  an edgeedge with one S(7)Rb2Er3 trigonal bipyramid,  an edgeedge with one S(9)Rb2Er3 trigonal bipyramid, and edges with two equivalent S(12)RbEr4 trigonal bipyramids. In the fifth S site, S(5) is bonded to two equivalent Rb(1), one Er(5), and two equivalent Er(7) atoms to form distorted SRb2Er3 trigonal bipyramids that share  a cornercorner with one S(3)Er5 square pyramid, corners with two equivalent S(1)Rb2Er3 square pyramids, corners with two equivalent S(7)Rb2Er3 trigonal bipyramids, corners with two equivalent S(9)Rb2Er3 trigonal bipyramids,  an edgeedge with one S(7)Rb2Er3 trigonal bipyramid,  an edgeedge with one S(9)Rb2Er3 trigonal bipyramid, edges with two equivalent S(5)Rb2Er3 trigonal bipyramids, edges with two equivalent S(11)RbEr4 trigonal bipyramids, and edges with two equivalent S(12)RbEr4 trigonal bipyramids. In the sixth S site, S(6) is bonded in a 6-coordinate geometry to one Rb(3), two equivalent Rb(2), one Er(6), and two equivalent Er(7) atoms. In the seventh S site, S(7) is bonded to two equivalent Rb(1), one Er(3), and two equivalent Er(2) atoms to form distorted SRb2Er3 trigonal bipyramids that share  a cornercorner with one S(1)Rb2Er3 square pyramid, corners with two equivalent S(3)Er5 square pyramids, corners with two equivalent S(4)Er5 square pyramids, corners with two equivalent S(5)Rb2Er3 trigonal bipyramids, corners with two equivalent S(9)Rb2Er3 trigonal bipyramids,  an edgeedge with one S(4)Er5 square pyramid,  an edgeedge with one S(5)Rb2Er3 trigonal bipyramid,  an edgeedge with one S(9)Rb2Er3 trigonal bipyramid, edges with two equivalent S(7)Rb2Er3 trigonal bipyramids, and edges with two equivalent S(12)RbEr4 trigonal bipyramids. In the eighth S site, S(8) is bonded to two equivalent Rb(2), one Er(4), and two equivalent Er(1) atoms to form distorted SRb2Er3 trigonal bipyramids that share corners with two equivalent S(3)Er5 square pyramids, corners with two equivalent S(4)Er5 square pyramids,  an edgeedge with one S(3)Er5 square pyramid, edges with two equivalent S(8)Rb2Er3 trigonal bipyramids, edges with two equivalent S(9)Rb2Er3 trigonal bipyramids, and edges with two equivalent S(11)RbEr4 trigonal bipyramids. In the ninth S site, S(9) is bonded to two equivalent Rb(1), one Er(1), and two equivalent Er(4) atoms to form distorted SRb2Er3 trigonal bipyramids that share corners with two equivalent S(3)Er5 square pyramids, corners with two equivalent S(4)Er5 square pyramids,  a cornercorner with one S(11)RbEr4 trigonal bipyramid, corners with two equivalent S(5)Rb2Er3 trigonal bipyramids, corners with two equivalent S(7)Rb2Er3 trigonal bipyramids, corners with two equivalent S(12)RbEr4 trigonal bipyramids,  an edgeedge with one S(4)Er5 square pyramid,  an edgeedge with one S(5)Rb2Er3 trigonal bipyramid,  an edgeedge with one S(7)Rb2Er3 trigonal bipyramid, edges with two equivalent S(8)Rb2Er3 trigonal bipyramids, and edges with two equivalent S(9)Rb2Er3 trigonal bipyramids. In the tenth S site, S(10) is bonded in a 6-coordinate geometry to one Rb(3), two equivalent Rb(2), one Er(2), and two equivalent Er(3) atoms. In the eleventh S site, S(11) is bonded to one Rb(2), one Er(1), one Er(7), and two equivalent Er(5) atoms to form distorted SRbEr4 trigonal bipyramids that share corners with two equivalent S(1)Rb2Er3 square pyramids,  a cornercorner with one S(9)Rb2Er3 trigonal bipyramid,  a cornercorner with one S(12)RbEr4 trigonal bipyramid, corners with two equivalent S(11)RbEr4 trigonal bipyramids,  an edgeedge with one S(1)Rb2Er3 square pyramid, edges with two equivalent S(3)Er5 square pyramids, edges with two equivalent S(5)Rb2Er3 trigonal bipyramids, and edges with two equivalent S(8)Rb2Er3 trigonal bipyramids. In the twelfth S site, S(12) is bonded to one Rb(1), one Er(2), one Er(7), and two equivalent Er(6) atoms to form distorted SRbEr4 trigonal bipyramids that share  a cornercorner with one S(11)RbEr4 trigonal bipyramid, corners with two equivalent S(9)Rb2Er3 trigonal bipyramids, corners with two equivalent S(12)RbEr4 trigonal bipyramids, edges with two equivalent S(4)Er5 square pyramids, edges with two equivalent S(5)Rb2Er3 trigonal bipyramids, and edges with two equivalent S(7)Rb2Er3 trigonal bipyramids.