Fe2SiS4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one S(1), one S(2), and four equivalent S(3) atoms to form FeS6 octahedra that share corners with four equivalent Fe(1)S6 octahedra, corners with four equivalent Fe(2)S6 octahedra, corners with four equivalent Si(1)S4 tetrahedra, edges with two equivalent Fe(2)S6 octahedra, and  an edgeedge with one Si(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-53°. In the second Fe site, Fe(2) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form FeS6 octahedra that share corners with four equivalent Fe(1)S6 octahedra, corners with two equivalent Si(1)S4 tetrahedra, edges with two equivalent Fe(1)S6 octahedra, edges with two equivalent Fe(2)S6 octahedra, and edges with two equivalent Si(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-53°. Si(1) is bonded to one S(1), one S(2), and two equivalent S(3) atoms to form SiS4 tetrahedra that share corners with two equivalent Fe(2)S6 octahedra, corners with four equivalent Fe(1)S6 octahedra,  an edgeedge with one Fe(1)S6 octahedra, and edges with two equivalent Fe(2)S6 octahedra. The corner-sharing octahedral tilt angles range from 58-61°. There are three inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Fe(1), two equivalent Fe(2), and one Si(1) atom. In the second S site, S(2) is bonded to one Fe(1), two equivalent Fe(2), and one Si(1) atom to form distorted corner-sharing SFe3Si trigonal pyramids. In the third S site, S(3) is bonded in a rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Si(1) atom.
Fe2SiS4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one S(1), one S(2), and four equivalent S(3) atoms to form FeS6 octahedra that share corners with four equivalent Fe(1)S6 octahedra, corners with four equivalent Fe(2)S6 octahedra, corners with four equivalent Si(1)S4 tetrahedra, edges with two equivalent Fe(2)S6 octahedra, and  an edgeedge with one Si(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-53°. The Fe(1)-S(1) bond length is 2.45 Å. The Fe(1)-S(2) bond length is 2.42 Å. There are two shorter (2.46 Å) and two longer (2.53 Å) Fe(1)-S(3) bond lengths. In the second Fe site, Fe(2) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form FeS6 octahedra that share corners with four equivalent Fe(1)S6 octahedra, corners with two equivalent Si(1)S4 tetrahedra, edges with two equivalent Fe(1)S6 octahedra, edges with two equivalent Fe(2)S6 octahedra, and edges with two equivalent Si(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-53°. Both Fe(2)-S(1) bond lengths are 2.49 Å. Both Fe(2)-S(2) bond lengths are 2.45 Å. Both Fe(2)-S(3) bond lengths are 2.50 Å. Si(1) is bonded to one S(1), one S(2), and two equivalent S(3) atoms to form SiS4 tetrahedra that share corners with two equivalent Fe(2)S6 octahedra, corners with four equivalent Fe(1)S6 octahedra,  an edgeedge with one Fe(1)S6 octahedra, and edges with two equivalent Fe(2)S6 octahedra. The corner-sharing octahedral tilt angles range from 58-61°. The Si(1)-S(1) bond length is 2.16 Å. The Si(1)-S(2) bond length is 2.15 Å. Both Si(1)-S(3) bond lengths are 2.16 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Fe(1), two equivalent Fe(2), and one Si(1) atom. In the second S site, S(2) is bonded to one Fe(1), two equivalent Fe(2), and one Si(1) atom to form distorted corner-sharing SFe3Si trigonal pyramids. In the third S site, S(3) is bonded in a rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Si(1) atom.