La2SiS5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 6-coordinate geometry to one S(3), one S(5), two equivalent S(1), and two equivalent S(4) atoms. In the second La site, La(2) is bonded to one S(3), one S(4), one S(5), two equivalent S(1), and two equivalent S(2) atoms to form distorted edge-sharing LaS7 pentagonal bipyramids. Si(1) is bonded in a trigonal planar geometry to one S(2), one S(3), and one S(5) atom. There are five inequivalent S sites. In the first S site, S(1) is bonded to two equivalent La(1) and two equivalent La(2) atoms to form a mixture of corner and edge-sharing SLa4 tetrahedra. In the second S site, S(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent La(2) and one Si(1) atom. In the third S site, S(3) is bonded in a 3-coordinate geometry to one La(1), one La(2), and one Si(1) atom. In the fourth S site, S(4) is bonded in a distorted T-shaped geometry to one La(2) and two equivalent La(1) atoms. In the fifth S site, S(5) is bonded in a 3-coordinate geometry to one La(1), one La(2), and one Si(1) atom.
La2SiS5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 6-coordinate geometry to one S(3), one S(5), two equivalent S(1), and two equivalent S(4) atoms. The La(1)-S(3) bond length is 3.18 Å. The La(1)-S(5) bond length is 3.19 Å. There is one shorter (2.87 Å) and one longer (2.90 Å) La(1)-S(1) bond length. There is one shorter (2.72 Å) and one longer (2.78 Å) La(1)-S(4) bond length. In the second La site, La(2) is bonded to one S(3), one S(4), one S(5), two equivalent S(1), and two equivalent S(2) atoms to form distorted edge-sharing LaS7 pentagonal bipyramids. The La(2)-S(3) bond length is 3.10 Å. The La(2)-S(4) bond length is 2.78 Å. The La(2)-S(5) bond length is 3.15 Å. Both La(2)-S(1) bond lengths are 2.87 Å. There is one shorter (2.97 Å) and one longer (3.02 Å) La(2)-S(2) bond length. Si(1) is bonded in a trigonal planar geometry to one S(2), one S(3), and one S(5) atom. The Si(1)-S(2) bond length is 2.06 Å. The Si(1)-S(3) bond length is 2.05 Å. The Si(1)-S(5) bond length is 2.04 Å. There are five inequivalent S sites. In the first S site, S(1) is bonded to two equivalent La(1) and two equivalent La(2) atoms to form a mixture of corner and edge-sharing SLa4 tetrahedra. In the second S site, S(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent La(2) and one Si(1) atom. In the third S site, S(3) is bonded in a 3-coordinate geometry to one La(1), one La(2), and one Si(1) atom. In the fourth S site, S(4) is bonded in a distorted T-shaped geometry to one La(2) and two equivalent La(1) atoms. In the fifth S site, S(5) is bonded in a 3-coordinate geometry to one La(1), one La(2), and one Si(1) atom.