Ca2SnS4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one S(1), two equivalent S(3), and three equivalent S(2) atoms to form a mixture of corner and edge-sharing CaS6 octahedra. The corner-sharing octahedral tilt angles range from 49-73°. In the second Ca site, Ca(2) is bonded to one S(3), two equivalent S(1), and three equivalent S(4) atoms to form a mixture of distorted corner and edge-sharing CaS6 octahedra. The corner-sharing octahedral tilt angles range from 49-73°. Sn(1) is bonded in a 7-coordinate geometry to one S(3), two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms. There are four inequivalent S sites. In the first S site, S(1) is bonded to one Ca(1), two equivalent Ca(2), and two equivalent Sn(1) atoms to form distorted SCa3Sn2 trigonal bipyramids that share corners with two equivalent S(3)Ca3Sn tetrahedra, corners with five equivalent S(2)Ca3Sn2 trigonal bipyramids, edges with two equivalent S(3)Ca3Sn tetrahedra,  an edgeedge with one S(2)Ca3Sn2 trigonal bipyramid, and edges with two equivalent S(1)Ca3Sn2 trigonal bipyramids. In the second S site, S(2) is bonded to three equivalent Ca(1) and two equivalent Sn(1) atoms to form distorted SCa3Sn2 trigonal bipyramids that share corners with six equivalent S(3)Ca3Sn tetrahedra, corners with five equivalent S(1)Ca3Sn2 trigonal bipyramids,  an edgeedge with one S(3)Ca3Sn tetrahedra,  an edgeedge with one S(1)Ca3Sn2 trigonal bipyramid, and edges with four equivalent S(2)Ca3Sn2 trigonal bipyramids. In the third S site, S(3) is bonded to one Ca(2), two equivalent Ca(1), and one Sn(1) atom to form distorted SCa3Sn tetrahedra that share corners with two equivalent S(3)Ca3Sn tetrahedra, corners with two equivalent S(1)Ca3Sn2 trigonal bipyramids, corners with six equivalent S(2)Ca3Sn2 trigonal bipyramids,  an edgeedge with one S(2)Ca3Sn2 trigonal bipyramid, and edges with two equivalent S(1)Ca3Sn2 trigonal bipyramids. In the fourth S site, S(4) is bonded in a 5-coordinate geometry to three equivalent Ca(2) and two equivalent Sn(1) atoms.
Ca2SnS4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one S(1), two equivalent S(3), and three equivalent S(2) atoms to form a mixture of corner and edge-sharing CaS6 octahedra. The corner-sharing octahedral tilt angles range from 49-73°. The Ca(1)-S(1) bond length is 2.92 Å. Both Ca(1)-S(3) bond lengths are 2.72 Å. There are two shorter (2.85 Å) and one longer (2.94 Å) Ca(1)-S(2) bond length. In the second Ca site, Ca(2) is bonded to one S(3), two equivalent S(1), and three equivalent S(4) atoms to form a mixture of distorted corner and edge-sharing CaS6 octahedra. The corner-sharing octahedral tilt angles range from 49-73°. The Ca(2)-S(3) bond length is 2.68 Å. Both Ca(2)-S(1) bond lengths are 2.81 Å. There is one shorter (2.80 Å) and two longer (2.97 Å) Ca(2)-S(4) bond lengths. Sn(1) is bonded in a 7-coordinate geometry to one S(3), two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms. The Sn(1)-S(3) bond length is 2.55 Å. Both Sn(1)-S(1) bond lengths are 2.77 Å. Both Sn(1)-S(2) bond lengths are 3.00 Å. Both Sn(1)-S(4) bond lengths are 2.76 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded to one Ca(1), two equivalent Ca(2), and two equivalent Sn(1) atoms to form distorted SCa3Sn2 trigonal bipyramids that share corners with two equivalent S(3)Ca3Sn tetrahedra, corners with five equivalent S(2)Ca3Sn2 trigonal bipyramids, edges with two equivalent S(3)Ca3Sn tetrahedra,  an edgeedge with one S(2)Ca3Sn2 trigonal bipyramid, and edges with two equivalent S(1)Ca3Sn2 trigonal bipyramids. In the second S site, S(2) is bonded to three equivalent Ca(1) and two equivalent Sn(1) atoms to form distorted SCa3Sn2 trigonal bipyramids that share corners with six equivalent S(3)Ca3Sn tetrahedra, corners with five equivalent S(1)Ca3Sn2 trigonal bipyramids,  an edgeedge with one S(3)Ca3Sn tetrahedra,  an edgeedge with one S(1)Ca3Sn2 trigonal bipyramid, and edges with four equivalent S(2)Ca3Sn2 trigonal bipyramids. In the third S site, S(3) is bonded to one Ca(2), two equivalent Ca(1), and one Sn(1) atom to form distorted SCa3Sn tetrahedra that share corners with two equivalent S(3)Ca3Sn tetrahedra, corners with two equivalent S(1)Ca3Sn2 trigonal bipyramids, corners with six equivalent S(2)Ca3Sn2 trigonal bipyramids,  an edgeedge with one S(2)Ca3Sn2 trigonal bipyramid, and edges with two equivalent S(1)Ca3Sn2 trigonal bipyramids. In the fourth S site, S(4) is bonded in a 5-coordinate geometry to three equivalent Ca(2) and two equivalent Sn(1) atoms.