Sm2SnS5 crystallizes in the orthorhombic Pbam space group. Sm(1) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(3), and four equivalent S(2) atoms. Sn(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form edge-sharing SnS6 octahedra. There are three inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Sm(1) and two equivalent Sn(1) atoms to form distorted SSm2Sn2 trigonal pyramids that share corners with four equivalent S(2)Sm4Sn trigonal bipyramids, corners with six equivalent S(1)Sm2Sn2 trigonal pyramids, edges with four equivalent S(2)Sm4Sn trigonal bipyramids, and  an edgeedge with one S(1)Sm2Sn2 trigonal pyramid. In the second S site, S(2) is bonded to four equivalent Sm(1) and one Sn(1) atom to form distorted SSm4Sn trigonal bipyramids that share corners with five equivalent S(2)Sm4Sn trigonal bipyramids, corners with four equivalent S(1)Sm2Sn2 trigonal pyramids, edges with four equivalent S(2)Sm4Sn trigonal bipyramids, and edges with four equivalent S(1)Sm2Sn2 trigonal pyramids. In the third S site, S(3) is bonded in a square co-planar geometry to four equivalent Sm(1) atoms.
Sm2SnS5 crystallizes in the orthorhombic Pbam space group. Sm(1) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(3), and four equivalent S(2) atoms. There is one shorter (2.89 Å) and one longer (3.00 Å) Sm(1)-S(1) bond length. Both Sm(1)-S(3) bond lengths are 2.78 Å. There are two shorter (2.94 Å) and two longer (3.02 Å) Sm(1)-S(2) bond lengths. Sn(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form edge-sharing SnS6 octahedra. Both Sn(1)-S(2) bond lengths are 2.59 Å. All Sn(1)-S(1) bond lengths are 2.57 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Sm(1) and two equivalent Sn(1) atoms to form distorted SSm2Sn2 trigonal pyramids that share corners with four equivalent S(2)Sm4Sn trigonal bipyramids, corners with six equivalent S(1)Sm2Sn2 trigonal pyramids, edges with four equivalent S(2)Sm4Sn trigonal bipyramids, and  an edgeedge with one S(1)Sm2Sn2 trigonal pyramid. In the second S site, S(2) is bonded to four equivalent Sm(1) and one Sn(1) atom to form distorted SSm4Sn trigonal bipyramids that share corners with five equivalent S(2)Sm4Sn trigonal bipyramids, corners with four equivalent S(1)Sm2Sn2 trigonal pyramids, edges with four equivalent S(2)Sm4Sn trigonal bipyramids, and edges with four equivalent S(1)Sm2Sn2 trigonal pyramids. In the third S site, S(3) is bonded in a square co-planar geometry to four equivalent Sm(1) atoms.