Sm4Ti4S4O9 crystallizes in the monoclinic Cm space group. There are four inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 9-coordinate geometry to two equivalent S(1), two equivalent S(4), one O(6), one O(7), one O(9), and two equivalent O(5) atoms. In the second Sm site, Sm(2) is bonded in a 8-coordinate geometry to two equivalent S(2), two equivalent S(3), one O(5), one O(8), and two equivalent O(6) atoms. In the third Sm site, Sm(3) is bonded in a 9-coordinate geometry to one S(1), two equivalent S(4), one O(2), one O(7), two equivalent O(1), and two equivalent O(3) atoms. In the fourth Sm site, Sm(4) is bonded in a 6-coordinate geometry to one S(2), two equivalent S(3), one O(1), one O(8), two equivalent O(2), and two equivalent O(4) atoms. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent S(1), two equivalent S(3), one O(1), and one O(9) atom to form distorted TiS4O2 octahedra that share corners with two equivalent Ti(4)SO5 trigonal bipyramids and edges with two equivalent Ti(1)S4O2 octahedra. In the second Ti site, Ti(2) is bonded in a 2-coordinate geometry to two equivalent S(2), two equivalent S(4), one O(2), and one O(9) atom. In the third Ti site, Ti(3) is bonded to one S(4), one O(3), one O(4), one O(5), and two equivalent O(7) atoms to form a mixture of distorted corner and edge-sharing TiSO5 trigonal bipyramids. In the fourth Ti site, Ti(4) is bonded to one S(3), one O(3), one O(4), one O(6), and two equivalent O(8) atoms to form distorted TiSO5 trigonal bipyramids that share corners with two equivalent Ti(1)S4O2 octahedra, corners with two equivalent Ti(4)SO5 trigonal bipyramids, and  an edgeedge with one Ti(3)SO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 47°. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted pentagonal planar geometry to one Sm(3), two equivalent Sm(1), and two equivalent Ti(1) atoms. In the second S site, S(2) is bonded in a 5-coordinate geometry to one Sm(4), two equivalent Sm(2), and two equivalent Ti(2) atoms. In the third S site, S(3) is bonded in a 7-coordinate geometry to two equivalent Sm(2), two equivalent Sm(4), one Ti(4), and two equivalent Ti(1) atoms. In the fourth S site, S(4) is bonded in a 7-coordinate geometry to two equivalent Sm(1), two equivalent Sm(3), one Ti(3), and two equivalent Ti(2) atoms. There are nine inequivalent O sites. In the first O site, O(1) is bonded to one Sm(4), two equivalent Sm(3), and one Ti(1) atom to form OSm3Ti tetrahedra that share  a cornercorner with one O(8)Sm2Ti2 tetrahedra, corners with two equivalent O(7)Sm2Ti2 tetrahedra, corners with two equivalent O(1)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm2Ti2 trigonal pyramids, corners with two equivalent O(4)Sm2Ti2 trigonal pyramids, edges with two equivalent O(2)Sm3Ti tetrahedra, and  an edgeedge with one O(3)Sm2Ti2 trigonal pyramid. In the second O site, O(2) is bonded to one Sm(3), two equivalent Sm(4), and one Ti(2) atom to form OSm3Ti tetrahedra that share  a cornercorner with one O(7)Sm2Ti2 tetrahedra, corners with two equivalent O(8)Sm2Ti2 tetrahedra, corners with two equivalent O(2)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm2Ti2 trigonal pyramids, corners with two equivalent O(4)Sm2Ti2 trigonal pyramids, edges with two equivalent O(1)Sm3Ti tetrahedra, and  an edgeedge with one O(4)Sm2Ti2 trigonal pyramid. In the third O site, O(3) is bonded to two equivalent Sm(3), one Ti(3), and one Ti(4) atom to form distorted OSm2Ti2 trigonal pyramids that share  a cornercorner with one O(5)Sm3Ti tetrahedra,  a cornercorner with one O(6)Sm3Ti tetrahedra, corners with two equivalent O(8)Sm2Ti2 tetrahedra, corners with two equivalent O(1)Sm3Ti tetrahedra, corners with two equivalent O(2)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm2Ti2 trigonal pyramids,  an edgeedge with one O(1)Sm3Ti tetrahedra, edges with two equivalent O(7)Sm2Ti2 tetrahedra, and  an edgeedge with one O(4)Sm2Ti2 trigonal pyramid. In the fourth O site, O(4) is bonded to two equivalent Sm(4), one Ti(3), and one Ti(4) atom to form distorted OSm2Ti2 trigonal pyramids that share  a cornercorner with one O(5)Sm3Ti tetrahedra,  a cornercorner with one O(6)Sm3Ti tetrahedra, corners with two equivalent O(7)Sm2Ti2 tetrahedra, corners with two equivalent O(1)Sm3Ti tetrahedra, corners with two equivalent O(2)Sm3Ti tetrahedra, corners with two equivalent O(4)Sm2Ti2 trigonal pyramids,  an edgeedge with one O(2)Sm3Ti tetrahedra, edges with two equivalent O(8)Sm2Ti2 tetrahedra, and  an edgeedge with one O(3)Sm2Ti2 trigonal pyramid. In the fifth O site, O(5) is bonded to one Sm(2), two equivalent Sm(1), and one Ti(3) atom to form OSm3Ti tetrahedra that share  a cornercorner with one O(8)Sm2Ti2 tetrahedra, corners with two equivalent O(5)Sm3Ti tetrahedra,  a cornercorner with one O(3)Sm2Ti2 trigonal pyramid,  a cornercorner with one O(4)Sm2Ti2 trigonal pyramid, edges with two equivalent O(7)Sm2Ti2 tetrahedra, and edges with two equivalent O(6)Sm3Ti tetrahedra. In the sixth O site, O(6) is bonded to one Sm(1), two equivalent Sm(2), and one Ti(4) atom to form distorted OSm3Ti tetrahedra that share  a cornercorner with one O(7)Sm2Ti2 tetrahedra, corners with two equivalent O(6)Sm3Ti tetrahedra,  a cornercorner with one O(3)Sm2Ti2 trigonal pyramid,  a cornercorner with one O(4)Sm2Ti2 trigonal pyramid, edges with two equivalent O(8)Sm2Ti2 tetrahedra, and edges with two equivalent O(5)Sm3Ti tetrahedra. In the seventh O site, O(7) is bonded to one Sm(1), one Sm(3), and two equivalent Ti(3) atoms to form distorted OSm2Ti2 tetrahedra that share  a cornercorner with one O(2)Sm3Ti tetrahedra,  a cornercorner with one O(6)Sm3Ti tetrahedra, corners with two equivalent O(7)Sm2Ti2 tetrahedra, corners with two equivalent O(1)Sm3Ti tetrahedra, corners with two equivalent O(4)Sm2Ti2 trigonal pyramids, edges with two equivalent O(5)Sm3Ti tetrahedra, and edges with two equivalent O(3)Sm2Ti2 trigonal pyramids. In the eighth O site, O(8) is bonded to one Sm(2), one Sm(4), and two equivalent Ti(4) atoms to form distorted OSm2Ti2 tetrahedra that share  a cornercorner with one O(1)Sm3Ti tetrahedra,  a cornercorner with one O(5)Sm3Ti tetrahedra, corners with two equivalent O(8)Sm2Ti2 tetrahedra, corners with two equivalent O(2)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm2Ti2 trigonal pyramids, edges with two equivalent O(6)Sm3Ti tetrahedra, and edges with two equivalent O(4)Sm2Ti2 trigonal pyramids. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Sm(1), one Ti(1), and one Ti(2) atom.
Sm4Ti4S4O9 crystallizes in the monoclinic Cm space group. There are four inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 9-coordinate geometry to two equivalent S(1), two equivalent S(4), one O(6), one O(7), one O(9), and two equivalent O(5) atoms. Both Sm(1)-S(1) bond lengths are 2.94 Å. Both Sm(1)-S(4) bond lengths are 2.98 Å. The Sm(1)-O(6) bond length is 2.46 Å. The Sm(1)-O(7) bond length is 2.55 Å. The Sm(1)-O(9) bond length is 2.65 Å. Both Sm(1)-O(5) bond lengths are 2.39 Å. In the second Sm site, Sm(2) is bonded in a 8-coordinate geometry to two equivalent S(2), two equivalent S(3), one O(5), one O(8), and two equivalent O(6) atoms. Both Sm(2)-S(2) bond lengths are 2.93 Å. Both Sm(2)-S(3) bond lengths are 3.01 Å. The Sm(2)-O(5) bond length is 2.38 Å. The Sm(2)-O(8) bond length is 2.50 Å. Both Sm(2)-O(6) bond lengths are 2.34 Å. In the third Sm site, Sm(3) is bonded in a 9-coordinate geometry to one S(1), two equivalent S(4), one O(2), one O(7), two equivalent O(1), and two equivalent O(3) atoms. The Sm(3)-S(1) bond length is 2.91 Å. Both Sm(3)-S(4) bond lengths are 2.97 Å. The Sm(3)-O(2) bond length is 2.45 Å. The Sm(3)-O(7) bond length is 2.58 Å. Both Sm(3)-O(1) bond lengths are 2.38 Å. Both Sm(3)-O(3) bond lengths are 2.49 Å. In the fourth Sm site, Sm(4) is bonded in a 6-coordinate geometry to one S(2), two equivalent S(3), one O(1), one O(8), two equivalent O(2), and two equivalent O(4) atoms. The Sm(4)-S(2) bond length is 3.04 Å. Both Sm(4)-S(3) bond lengths are 3.11 Å. The Sm(4)-O(1) bond length is 2.43 Å. The Sm(4)-O(8) bond length is 2.57 Å. Both Sm(4)-O(2) bond lengths are 2.36 Å. Both Sm(4)-O(4) bond lengths are 2.49 Å. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent S(1), two equivalent S(3), one O(1), and one O(9) atom to form distorted TiS4O2 octahedra that share corners with two equivalent Ti(4)SO5 trigonal bipyramids and edges with two equivalent Ti(1)S4O2 octahedra. Both Ti(1)-S(1) bond lengths are 2.55 Å. Both Ti(1)-S(3) bond lengths are 2.58 Å. The Ti(1)-O(1) bond length is 1.89 Å. The Ti(1)-O(9) bond length is 1.87 Å. In the second Ti site, Ti(2) is bonded in a 2-coordinate geometry to two equivalent S(2), two equivalent S(4), one O(2), and one O(9) atom. Both Ti(2)-S(2) bond lengths are 2.51 Å. Both Ti(2)-S(4) bond lengths are 2.61 Å. The Ti(2)-O(2) bond length is 1.90 Å. The Ti(2)-O(9) bond length is 1.87 Å. In the third Ti site, Ti(3) is bonded to one S(4), one O(3), one O(4), one O(5), and two equivalent O(7) atoms to form a mixture of distorted corner and edge-sharing TiSO5 trigonal bipyramids. The Ti(3)-S(4) bond length is 2.95 Å. The Ti(3)-O(3) bond length is 2.12 Å. The Ti(3)-O(4) bond length is 1.88 Å. The Ti(3)-O(5) bond length is 1.97 Å. Both Ti(3)-O(7) bond lengths are 1.94 Å. In the fourth Ti site, Ti(4) is bonded to one S(3), one O(3), one O(4), one O(6), and two equivalent O(8) atoms to form distorted TiSO5 trigonal bipyramids that share corners with two equivalent Ti(1)S4O2 octahedra, corners with two equivalent Ti(4)SO5 trigonal bipyramids, and  an edgeedge with one Ti(3)SO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 47°. The Ti(4)-S(3) bond length is 3.08 Å. The Ti(4)-O(3) bond length is 1.85 Å. The Ti(4)-O(4) bond length is 2.13 Å. The Ti(4)-O(6) bond length is 1.96 Å. Both Ti(4)-O(8) bond lengths are 1.95 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted pentagonal planar geometry to one Sm(3), two equivalent Sm(1), and two equivalent Ti(1) atoms. In the second S site, S(2) is bonded in a 5-coordinate geometry to one Sm(4), two equivalent Sm(2), and two equivalent Ti(2) atoms. In the third S site, S(3) is bonded in a 7-coordinate geometry to two equivalent Sm(2), two equivalent Sm(4), one Ti(4), and two equivalent Ti(1) atoms. In the fourth S site, S(4) is bonded in a 7-coordinate geometry to two equivalent Sm(1), two equivalent Sm(3), one Ti(3), and two equivalent Ti(2) atoms. There are nine inequivalent O sites. In the first O site, O(1) is bonded to one Sm(4), two equivalent Sm(3), and one Ti(1) atom to form OSm3Ti tetrahedra that share  a cornercorner with one O(8)Sm2Ti2 tetrahedra, corners with two equivalent O(7)Sm2Ti2 tetrahedra, corners with two equivalent O(1)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm2Ti2 trigonal pyramids, corners with two equivalent O(4)Sm2Ti2 trigonal pyramids, edges with two equivalent O(2)Sm3Ti tetrahedra, and  an edgeedge with one O(3)Sm2Ti2 trigonal pyramid. In the second O site, O(2) is bonded to one Sm(3), two equivalent Sm(4), and one Ti(2) atom to form OSm3Ti tetrahedra that share  a cornercorner with one O(7)Sm2Ti2 tetrahedra, corners with two equivalent O(8)Sm2Ti2 tetrahedra, corners with two equivalent O(2)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm2Ti2 trigonal pyramids, corners with two equivalent O(4)Sm2Ti2 trigonal pyramids, edges with two equivalent O(1)Sm3Ti tetrahedra, and  an edgeedge with one O(4)Sm2Ti2 trigonal pyramid. In the third O site, O(3) is bonded to two equivalent Sm(3), one Ti(3), and one Ti(4) atom to form distorted OSm2Ti2 trigonal pyramids that share  a cornercorner with one O(5)Sm3Ti tetrahedra,  a cornercorner with one O(6)Sm3Ti tetrahedra, corners with two equivalent O(8)Sm2Ti2 tetrahedra, corners with two equivalent O(1)Sm3Ti tetrahedra, corners with two equivalent O(2)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm2Ti2 trigonal pyramids,  an edgeedge with one O(1)Sm3Ti tetrahedra, edges with two equivalent O(7)Sm2Ti2 tetrahedra, and  an edgeedge with one O(4)Sm2Ti2 trigonal pyramid. In the fourth O site, O(4) is bonded to two equivalent Sm(4), one Ti(3), and one Ti(4) atom to form distorted OSm2Ti2 trigonal pyramids that share  a cornercorner with one O(5)Sm3Ti tetrahedra,  a cornercorner with one O(6)Sm3Ti tetrahedra, corners with two equivalent O(7)Sm2Ti2 tetrahedra, corners with two equivalent O(1)Sm3Ti tetrahedra, corners with two equivalent O(2)Sm3Ti tetrahedra, corners with two equivalent O(4)Sm2Ti2 trigonal pyramids,  an edgeedge with one O(2)Sm3Ti tetrahedra, edges with two equivalent O(8)Sm2Ti2 tetrahedra, and  an edgeedge with one O(3)Sm2Ti2 trigonal pyramid. In the fifth O site, O(5) is bonded to one Sm(2), two equivalent Sm(1), and one Ti(3) atom to form OSm3Ti tetrahedra that share  a cornercorner with one O(8)Sm2Ti2 tetrahedra, corners with two equivalent O(5)Sm3Ti tetrahedra,  a cornercorner with one O(3)Sm2Ti2 trigonal pyramid,  a cornercorner with one O(4)Sm2Ti2 trigonal pyramid, edges with two equivalent O(7)Sm2Ti2 tetrahedra, and edges with two equivalent O(6)Sm3Ti tetrahedra. In the sixth O site, O(6) is bonded to one Sm(1), two equivalent Sm(2), and one Ti(4) atom to form distorted OSm3Ti tetrahedra that share  a cornercorner with one O(7)Sm2Ti2 tetrahedra, corners with two equivalent O(6)Sm3Ti tetrahedra,  a cornercorner with one O(3)Sm2Ti2 trigonal pyramid,  a cornercorner with one O(4)Sm2Ti2 trigonal pyramid, edges with two equivalent O(8)Sm2Ti2 tetrahedra, and edges with two equivalent O(5)Sm3Ti tetrahedra. In the seventh O site, O(7) is bonded to one Sm(1), one Sm(3), and two equivalent Ti(3) atoms to form distorted OSm2Ti2 tetrahedra that share  a cornercorner with one O(2)Sm3Ti tetrahedra,  a cornercorner with one O(6)Sm3Ti tetrahedra, corners with two equivalent O(7)Sm2Ti2 tetrahedra, corners with two equivalent O(1)Sm3Ti tetrahedra, corners with two equivalent O(4)Sm2Ti2 trigonal pyramids, edges with two equivalent O(5)Sm3Ti tetrahedra, and edges with two equivalent O(3)Sm2Ti2 trigonal pyramids. In the eighth O site, O(8) is bonded to one Sm(2), one Sm(4), and two equivalent Ti(4) atoms to form distorted OSm2Ti2 tetrahedra that share  a cornercorner with one O(1)Sm3Ti tetrahedra,  a cornercorner with one O(5)Sm3Ti tetrahedra, corners with two equivalent O(8)Sm2Ti2 tetrahedra, corners with two equivalent O(2)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm2Ti2 trigonal pyramids, edges with two equivalent O(6)Sm3Ti tetrahedra, and edges with two equivalent O(4)Sm2Ti2 trigonal pyramids. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Sm(1), one Ti(1), and one Ti(2) atom.