La2S3 crystallizes in the tetragonal I-42d space group. There are three inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(3), and four equivalent S(2) atoms. In the second La site, La(2) is bonded to two equivalent S(2), two equivalent S(3), and four equivalent S(1) atoms to form distorted edge-sharing LaS8 hexagonal bipyramids. In the third La site, La(3) is bonded in a 8-coordinate geometry to two equivalent S(1), three equivalent S(2), and three equivalent S(3) atoms. There are three inequivalent S sites. In the first S site, S(1) is bonded to one La(1), two equivalent La(2), and two equivalent La(3) atoms to form SLa5 trigonal bipyramids that share corners with five equivalent S(2)La6 octahedra, corners with four equivalent S(3)La5 square pyramids, corners with four equivalent S(1)La5 trigonal bipyramids, edges with three equivalent S(2)La6 octahedra, edges with four equivalent S(3)La5 square pyramids,  an edgeedge with one S(1)La5 trigonal bipyramid,  a faceface with one S(2)La6 octahedra, and  a faceface with one S(1)La5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 25-51°. In the second S site, S(2) is bonded to one La(2), two equivalent La(1), and three equivalent La(3) atoms to form distorted SLa6 octahedra that share corners with three equivalent S(2)La6 octahedra, corners with seven equivalent S(3)La5 square pyramids, corners with five equivalent S(1)La5 trigonal bipyramids, edges with two equivalent S(2)La6 octahedra,  an edgeedge with one S(3)La5 square pyramid, edges with three equivalent S(1)La5 trigonal bipyramids, faces with two equivalent S(2)La6 octahedra, faces with two equivalent S(3)La5 square pyramids, and  a faceface with one S(1)La5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 19-48°. In the third S site, S(3) is bonded to one La(1), one La(2), and three equivalent La(3) atoms to form distorted SLa5 square pyramids that share corners with seven equivalent S(2)La6 octahedra, corners with five equivalent S(3)La5 square pyramids, corners with four equivalent S(1)La5 trigonal bipyramids,  an edgeedge with one S(2)La6 octahedra, edges with four equivalent S(1)La5 trigonal bipyramids, faces with two equivalent S(2)La6 octahedra, and  a faceface with one S(3)La5 square pyramid. The corner-sharing octahedral tilt angles range from 11-55°.
La2S3 crystallizes in the tetragonal I-42d space group. There are three inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(3), and four equivalent S(2) atoms. Both La(1)-S(1) bond lengths are 2.90 Å. Both La(1)-S(3) bond lengths are 3.14 Å. There are two shorter (2.94 Å) and two longer (3.07 Å) La(1)-S(2) bond lengths. In the second La site, La(2) is bonded to two equivalent S(2), two equivalent S(3), and four equivalent S(1) atoms to form distorted edge-sharing LaS8 hexagonal bipyramids. Both La(2)-S(2) bond lengths are 3.18 Å. Both La(2)-S(3) bond lengths are 2.94 Å. There are two shorter (2.92 Å) and two longer (3.13 Å) La(2)-S(1) bond lengths. In the third La site, La(3) 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 (2.88 Å) and one longer (3.11 Å) La(3)-S(1) bond length. There are a spread of La(3)-S(2) bond distances ranging from 2.91-3.33 Å. There are a spread of La(3)-S(3) bond distances ranging from 2.88-3.11 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded to one La(1), two equivalent La(2), and two equivalent La(3) atoms to form SLa5 trigonal bipyramids that share corners with five equivalent S(2)La6 octahedra, corners with four equivalent S(3)La5 square pyramids, corners with four equivalent S(1)La5 trigonal bipyramids, edges with three equivalent S(2)La6 octahedra, edges with four equivalent S(3)La5 square pyramids,  an edgeedge with one S(1)La5 trigonal bipyramid,  a faceface with one S(2)La6 octahedra, and  a faceface with one S(1)La5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 25-51°. In the second S site, S(2) is bonded to one La(2), two equivalent La(1), and three equivalent La(3) atoms to form distorted SLa6 octahedra that share corners with three equivalent S(2)La6 octahedra, corners with seven equivalent S(3)La5 square pyramids, corners with five equivalent S(1)La5 trigonal bipyramids, edges with two equivalent S(2)La6 octahedra,  an edgeedge with one S(3)La5 square pyramid, edges with three equivalent S(1)La5 trigonal bipyramids, faces with two equivalent S(2)La6 octahedra, faces with two equivalent S(3)La5 square pyramids, and  a faceface with one S(1)La5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 19-48°. In the third S site, S(3) is bonded to one La(1), one La(2), and three equivalent La(3) atoms to form distorted SLa5 square pyramids that share corners with seven equivalent S(2)La6 octahedra, corners with five equivalent S(3)La5 square pyramids, corners with four equivalent S(1)La5 trigonal bipyramids,  an edgeedge with one S(2)La6 octahedra, edges with four equivalent S(1)La5 trigonal bipyramids, faces with two equivalent S(2)La6 octahedra, and  a faceface with one S(3)La5 square pyramid. The corner-sharing octahedral tilt angles range from 11-55°.