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 CaS6 octahedra that share corners with three equivalent Ca(2)S6 octahedra, corners with four equivalent Sn(1)S7 pentagonal bipyramids, edges with two equivalent Ca(2)S6 octahedra, edges with four equivalent Ca(1)S6 octahedra, and  an edgeedge with one Sn(1)S7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 51-58°. In the second Ca site, Ca(2) is bonded to one S(2), one S(3), two equivalent S(1), and two equivalent S(4) atoms to form distorted CaS6 octahedra that share corners with three equivalent Ca(1)S6 octahedra, corners with four equivalent Sn(1)S7 pentagonal bipyramids, edges with two equivalent Ca(1)S6 octahedra, edges with two equivalent Ca(2)S6 octahedra, and edges with four equivalent Sn(1)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 51-58°. Sn(1) is bonded to two equivalent S(1), two equivalent S(3), and three equivalent S(4) atoms to form distorted SnS7 pentagonal bipyramids that share corners with four equivalent Ca(1)S6 octahedra, corners with four equivalent Ca(2)S6 octahedra,  an edgeedge with one Ca(1)S6 octahedra, edges with four equivalent Ca(2)S6 octahedra, edges with two equivalent Sn(1)S7 pentagonal bipyramids, and faces with two equivalent Sn(1)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 21-62°. 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)Ca3Sn2 square pyramids, corners with six equivalent S(4)Ca2Sn3 square pyramids, edges with two equivalent S(4)Ca2Sn3 square pyramids, edges with three equivalent S(3)Ca3Sn2 square pyramids, and edges with two equivalent S(1)Ca3Sn2 trigonal bipyramids. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to one Ca(2) and three equivalent Ca(1) atoms. In the third S site, S(3) is bonded to one Ca(2), two equivalent Ca(1), and two equivalent Sn(1) atoms to form SCa3Sn2 square pyramids that share corners with two equivalent S(4)Ca2Sn3 square pyramids, corners with two equivalent S(1)Ca3Sn2 trigonal bipyramids, edges with two equivalent S(3)Ca3Sn2 square pyramids, edges with three equivalent S(4)Ca2Sn3 square pyramids, and edges with three equivalent S(1)Ca3Sn2 trigonal bipyramids. In the fourth S site, S(4) is bonded to two equivalent Ca(2) and three equivalent Sn(1) atoms to form distorted SCa2Sn3 square pyramids that share corners with two equivalent S(3)Ca3Sn2 square pyramids, corners with six equivalent S(1)Ca3Sn2 trigonal bipyramids, edges with three equivalent S(3)Ca3Sn2 square pyramids, edges with four equivalent S(4)Ca2Sn3 square pyramids, and edges with two equivalent S(1)Ca3Sn2 trigonal bipyramids.
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 CaS6 octahedra that share corners with three equivalent Ca(2)S6 octahedra, corners with four equivalent Sn(1)S7 pentagonal bipyramids, edges with two equivalent Ca(2)S6 octahedra, edges with four equivalent Ca(1)S6 octahedra, and  an edgeedge with one Sn(1)S7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 51-58°. The Ca(1)-S(1) bond length is 2.89 Å. Both Ca(1)-S(3) bond lengths are 2.97 Å. There are two shorter (2.70 Å) and one longer (2.76 Å) Ca(1)-S(2) bond length. In the second Ca site, Ca(2) is bonded to one S(2), one S(3), two equivalent S(1), and two equivalent S(4) atoms to form distorted CaS6 octahedra that share corners with three equivalent Ca(1)S6 octahedra, corners with four equivalent Sn(1)S7 pentagonal bipyramids, edges with two equivalent Ca(1)S6 octahedra, edges with two equivalent Ca(2)S6 octahedra, and edges with four equivalent Sn(1)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 51-58°. The Ca(2)-S(2) bond length is 2.64 Å. The Ca(2)-S(3) bond length is 2.84 Å. Both Ca(2)-S(1) bond lengths are 2.83 Å. Both Ca(2)-S(4) bond lengths are 2.94 Å. Sn(1) is bonded to two equivalent S(1), two equivalent S(3), and three equivalent S(4) atoms to form distorted SnS7 pentagonal bipyramids that share corners with four equivalent Ca(1)S6 octahedra, corners with four equivalent Ca(2)S6 octahedra,  an edgeedge with one Ca(1)S6 octahedra, edges with four equivalent Ca(2)S6 octahedra, edges with two equivalent Sn(1)S7 pentagonal bipyramids, and faces with two equivalent Sn(1)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 21-62°. Both Sn(1)-S(1) bond lengths are 2.89 Å. Both Sn(1)-S(3) bond lengths are 2.68 Å. There are two shorter (2.70 Å) and one longer (2.87 Å) Sn(1)-S(4) bond length. 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)Ca3Sn2 square pyramids, corners with six equivalent S(4)Ca2Sn3 square pyramids, edges with two equivalent S(4)Ca2Sn3 square pyramids, edges with three equivalent S(3)Ca3Sn2 square pyramids, and edges with two equivalent S(1)Ca3Sn2 trigonal bipyramids. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to one Ca(2) and three equivalent Ca(1) atoms. In the third S site, S(3) is bonded to one Ca(2), two equivalent Ca(1), and two equivalent Sn(1) atoms to form SCa3Sn2 square pyramids that share corners with two equivalent S(4)Ca2Sn3 square pyramids, corners with two equivalent S(1)Ca3Sn2 trigonal bipyramids, edges with two equivalent S(3)Ca3Sn2 square pyramids, edges with three equivalent S(4)Ca2Sn3 square pyramids, and edges with three equivalent S(1)Ca3Sn2 trigonal bipyramids. In the fourth S site, S(4) is bonded to two equivalent Ca(2) and three equivalent Sn(1) atoms to form distorted SCa2Sn3 square pyramids that share corners with two equivalent S(3)Ca3Sn2 square pyramids, corners with six equivalent S(1)Ca3Sn2 trigonal bipyramids, edges with three equivalent S(3)Ca3Sn2 square pyramids, edges with four equivalent S(4)Ca2Sn3 square pyramids, and edges with two equivalent S(1)Ca3Sn2 trigonal bipyramids.