Tm2S3 crystallizes in the tetragonal I-42d space group. There are three inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 8-coordinate geometry to two equivalent S(1), three equivalent S(2), and three equivalent S(3) atoms. In the second Tm site, Tm(2) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(3), and four equivalent S(2) atoms. In the third Tm site, Tm(3) is bonded in a 8-coordinate geometry to two equivalent S(2), two equivalent S(3), and four equivalent S(1) atoms. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Tm(2), two equivalent Tm(1), and two equivalent Tm(3) atoms to form distorted STm5 trigonal bipyramids that share corners with five equivalent S(2)Tm6 octahedra, corners with four equivalent S(3)Tm5 square pyramids, corners with four equivalent S(1)Tm5 trigonal bipyramids, edges with three equivalent S(2)Tm6 octahedra, edges with four equivalent S(3)Tm5 square pyramids,  an edgeedge with one S(1)Tm5 trigonal bipyramid,  a faceface with one S(2)Tm6 octahedra, and  a faceface with one S(1)Tm5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 26-51°. In the second S site, S(2) is bonded to one Tm(3), two equivalent Tm(2), and three equivalent Tm(1) atoms to form distorted STm6 octahedra that share corners with three equivalent S(2)Tm6 octahedra, corners with seven equivalent S(3)Tm5 square pyramids, corners with five equivalent S(1)Tm5 trigonal bipyramids, edges with two equivalent S(2)Tm6 octahedra,  an edgeedge with one S(3)Tm5 square pyramid, edges with three equivalent S(1)Tm5 trigonal bipyramids, faces with two equivalent S(2)Tm6 octahedra, faces with two equivalent S(3)Tm5 square pyramids, and  a faceface with one S(1)Tm5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 21-47°. In the third S site, S(3) is bonded to one Tm(2), one Tm(3), and three equivalent Tm(1) atoms to form distorted STm5 square pyramids that share corners with seven equivalent S(2)Tm6 octahedra, corners with five equivalent S(3)Tm5 square pyramids, corners with four equivalent S(1)Tm5 trigonal bipyramids,  an edgeedge with one S(2)Tm6 octahedra, edges with four equivalent S(1)Tm5 trigonal bipyramids, faces with two equivalent S(2)Tm6 octahedra, and  a faceface with one S(3)Tm5 square pyramid. The corner-sharing octahedral tilt angles range from 14-54°.
Tm2S3 crystallizes in the tetragonal I-42d space group. There are three inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 8-coordinate geometry to two equivalent S(1), three equivalent S(2), and three equivalent S(3) atoms. There is one shorter (2.69 Å) and one longer (2.96 Å) Tm(1)-S(1) bond length. There are a spread of Tm(1)-S(2) bond distances ranging from 2.71-3.17 Å. There are a spread of Tm(1)-S(3) bond distances ranging from 2.68-2.95 Å. In the second Tm site, Tm(2) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(3), and four equivalent S(2) atoms. Both Tm(2)-S(1) bond lengths are 2.71 Å. Both Tm(2)-S(3) bond lengths are 2.99 Å. There are two shorter (2.71 Å) and two longer (2.92 Å) Tm(2)-S(2) bond lengths. In the third Tm site, Tm(3) is bonded in a 8-coordinate geometry to two equivalent S(2), two equivalent S(3), and four equivalent S(1) atoms. Both Tm(3)-S(2) bond lengths are 3.06 Å. Both Tm(3)-S(3) bond lengths are 2.73 Å. There are two shorter (2.72 Å) and two longer (2.93 Å) Tm(3)-S(1) bond lengths. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Tm(2), two equivalent Tm(1), and two equivalent Tm(3) atoms to form distorted STm5 trigonal bipyramids that share corners with five equivalent S(2)Tm6 octahedra, corners with four equivalent S(3)Tm5 square pyramids, corners with four equivalent S(1)Tm5 trigonal bipyramids, edges with three equivalent S(2)Tm6 octahedra, edges with four equivalent S(3)Tm5 square pyramids,  an edgeedge with one S(1)Tm5 trigonal bipyramid,  a faceface with one S(2)Tm6 octahedra, and  a faceface with one S(1)Tm5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 26-51°. In the second S site, S(2) is bonded to one Tm(3), two equivalent Tm(2), and three equivalent Tm(1) atoms to form distorted STm6 octahedra that share corners with three equivalent S(2)Tm6 octahedra, corners with seven equivalent S(3)Tm5 square pyramids, corners with five equivalent S(1)Tm5 trigonal bipyramids, edges with two equivalent S(2)Tm6 octahedra,  an edgeedge with one S(3)Tm5 square pyramid, edges with three equivalent S(1)Tm5 trigonal bipyramids, faces with two equivalent S(2)Tm6 octahedra, faces with two equivalent S(3)Tm5 square pyramids, and  a faceface with one S(1)Tm5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 21-47°. In the third S site, S(3) is bonded to one Tm(2), one Tm(3), and three equivalent Tm(1) atoms to form distorted STm5 square pyramids that share corners with seven equivalent S(2)Tm6 octahedra, corners with five equivalent S(3)Tm5 square pyramids, corners with four equivalent S(1)Tm5 trigonal bipyramids,  an edgeedge with one S(2)Tm6 octahedra, edges with four equivalent S(1)Tm5 trigonal bipyramids, faces with two equivalent S(2)Tm6 octahedra, and  a faceface with one S(3)Tm5 square pyramid. The corner-sharing octahedral tilt angles range from 14-54°.