Ca2SiS4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form CaS6 octahedra that share corners with four equivalent Ca(2)S6 octahedra, corners with two equivalent Si(1)S4 tetrahedra, edges with two equivalent Ca(1)S6 octahedra, edges with two equivalent Ca(2)S6 octahedra, and edges with two equivalent Si(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-66°. In the second Ca site, Ca(2) is bonded to one S(2), one S(3), and four equivalent S(1) atoms to form CaS6 octahedra that share corners with four equivalent Ca(1)S6 octahedra, corners with four equivalent Ca(2)S6 octahedra, corners with four equivalent Si(1)S4 tetrahedra, edges with two equivalent Ca(1)S6 octahedra, and  an edgeedge with one Si(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-66°. Si(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form SiS4 tetrahedra that share corners with two equivalent Ca(1)S6 octahedra, corners with four equivalent Ca(2)S6 octahedra,  an edgeedge with one Ca(2)S6 octahedra, and edges with two equivalent Ca(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 52-59°. There are three inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Ca(1), two equivalent Ca(2), and one Si(1) atom. In the second S site, S(2) is bonded to one Ca(2), two equivalent Ca(1), and one Si(1) atom to form distorted corner-sharing SCa3Si trigonal pyramids. In the third S site, S(3) is bonded in a rectangular see-saw-like geometry to one Ca(2), two equivalent Ca(1), and one Si(1) atom.
Ca2SiS4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form CaS6 octahedra that share corners with four equivalent Ca(2)S6 octahedra, corners with two equivalent Si(1)S4 tetrahedra, edges with two equivalent Ca(1)S6 octahedra, edges with two equivalent Ca(2)S6 octahedra, and edges with two equivalent Si(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-66°. Both Ca(1)-S(1) bond lengths are 2.85 Å. Both Ca(1)-S(2) bond lengths are 2.88 Å. Both Ca(1)-S(3) bond lengths are 2.78 Å. In the second Ca site, Ca(2) is bonded to one S(2), one S(3), and four equivalent S(1) atoms to form CaS6 octahedra that share corners with four equivalent Ca(1)S6 octahedra, corners with four equivalent Ca(2)S6 octahedra, corners with four equivalent Si(1)S4 tetrahedra, edges with two equivalent Ca(1)S6 octahedra, and  an edgeedge with one Si(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-66°. The Ca(2)-S(2) bond length is 2.87 Å. The Ca(2)-S(3) bond length is 2.79 Å. There are two shorter (2.85 Å) and two longer (2.87 Å) Ca(2)-S(1) bond lengths. Si(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form SiS4 tetrahedra that share corners with two equivalent Ca(1)S6 octahedra, corners with four equivalent Ca(2)S6 octahedra,  an edgeedge with one Ca(2)S6 octahedra, and edges with two equivalent Ca(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 52-59°. The Si(1)-S(2) bond length is 2.11 Å. The Si(1)-S(3) bond length is 2.14 Å. Both Si(1)-S(1) bond lengths are 2.14 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 Ca(1), two equivalent Ca(2), and one Si(1) atom. In the second S site, S(2) is bonded to one Ca(2), two equivalent Ca(1), and one Si(1) atom to form distorted corner-sharing SCa3Si trigonal pyramids. In the third S site, S(3) is bonded in a rectangular see-saw-like geometry to one Ca(2), two equivalent Ca(1), and one Si(1) atom.