La3CoSiS7 crystallizes in the hexagonal P6_3 space group. La(1) is bonded in a 8-coordinate geometry to one S(1), three equivalent S(2), and four equivalent S(3) atoms. Co(1) is bonded to six equivalent S(3) atoms to form face-sharing CoS6 octahedra. Si(1) is bonded in a tetrahedral geometry to one S(1) and three equivalent S(2) atoms. There are three inequivalent S sites. In the first S site, S(1) is bonded to three equivalent La(1) and one Si(1) atom to form distorted corner-sharing SLa3Si tetrahedra. In the second S site, S(2) is bonded in a distorted rectangular see-saw-like geometry to three equivalent La(1) and one Si(1) atom. In the third S site, S(3) is bonded to four equivalent La(1) and two equivalent Co(1) atoms to form distorted SLa4Co2 pentagonal pyramids that share corners with four equivalent S(3)La4Co2 pentagonal pyramids, corners with four equivalent S(1)La3Si tetrahedra, and faces with six equivalent S(3)La4Co2 pentagonal pyramids.
La3CoSiS7 crystallizes in the hexagonal P6_3 space group. La(1) is bonded in a 8-coordinate geometry to one S(1), three equivalent S(2), and four equivalent S(3) atoms. The La(1)-S(1) bond length is 3.12 Å. There are a spread of La(1)-S(2) bond distances ranging from 2.94-3.05 Å. There are a spread of La(1)-S(3) bond distances ranging from 2.83-3.14 Å. Co(1) is bonded to six equivalent S(3) atoms to form face-sharing CoS6 octahedra. All Co(1)-S(3) bond lengths are 2.57 Å. Si(1) is bonded in a tetrahedral geometry to one S(1) and three equivalent S(2) atoms. The Si(1)-S(1) bond length is 2.10 Å. All Si(1)-S(2) bond lengths are 2.14 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded to three equivalent La(1) and one Si(1) atom to form distorted corner-sharing SLa3Si tetrahedra. In the second S site, S(2) is bonded in a distorted rectangular see-saw-like geometry to three equivalent La(1) and one Si(1) atom. In the third S site, S(3) is bonded to four equivalent La(1) and two equivalent Co(1) atoms to form distorted SLa4Co2 pentagonal pyramids that share corners with four equivalent S(3)La4Co2 pentagonal pyramids, corners with four equivalent S(1)La3Si tetrahedra, and faces with six equivalent S(3)La4Co2 pentagonal pyramids.