Sm2S2O crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 7-coordinate geometry to two equivalent S(2), four equivalent S(1), and one O(1) atom. In the second Sm site, Sm(2) is bonded in a 7-coordinate geometry to one S(1), three equivalent S(2), and three equivalent O(1) atoms. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Sm(2) and four equivalent Sm(1) atoms to form distorted SSm5 trigonal bipyramids that share corners with three equivalent O(1)Sm4 tetrahedra, corners with four equivalent S(1)Sm5 trigonal bipyramids, edges with two equivalent O(1)Sm4 tetrahedra, and edges with four equivalent S(1)Sm5 trigonal bipyramids. In the second S site, S(2) is bonded in a 5-coordinate geometry to two equivalent Sm(1) and three equivalent Sm(2) atoms. O(1) is bonded to one Sm(1) and three equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with four equivalent O(1)Sm4 tetrahedra, corners with three equivalent S(1)Sm5 trigonal bipyramids,  an edgeedge with one O(1)Sm4 tetrahedra, and edges with two equivalent S(1)Sm5 trigonal bipyramids.
Sm2S2O crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 7-coordinate geometry to two equivalent S(2), four equivalent S(1), and one O(1) atom. There is one shorter (2.84 Å) and one longer (2.98 Å) Sm(1)-S(2) bond length. There are a spread of Sm(1)-S(1) bond distances ranging from 2.81-2.92 Å. The Sm(1)-O(1) bond length is 2.31 Å. In the second Sm site, Sm(2) is bonded in a 7-coordinate geometry to one S(1), three equivalent S(2), and three equivalent O(1) atoms. The Sm(2)-S(1) bond length is 2.99 Å. There are a spread of Sm(2)-S(2) bond distances ranging from 2.84-3.18 Å. There are a spread of Sm(2)-O(1) bond distances ranging from 2.32-2.34 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Sm(2) and four equivalent Sm(1) atoms to form distorted SSm5 trigonal bipyramids that share corners with three equivalent O(1)Sm4 tetrahedra, corners with four equivalent S(1)Sm5 trigonal bipyramids, edges with two equivalent O(1)Sm4 tetrahedra, and edges with four equivalent S(1)Sm5 trigonal bipyramids. In the second S site, S(2) is bonded in a 5-coordinate geometry to two equivalent Sm(1) and three equivalent Sm(2) atoms. O(1) is bonded to one Sm(1) and three equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with four equivalent O(1)Sm4 tetrahedra, corners with three equivalent S(1)Sm5 trigonal bipyramids,  an edgeedge with one O(1)Sm4 tetrahedra, and edges with two equivalent S(1)Sm5 trigonal bipyramids.