Ca2SnS4 crystallizes in the hexagonal P-62m space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to six equivalent S(1) atoms to form distorted CaS6 pentagonal pyramids that share corners with six equivalent Sn(1)S6 octahedra, edges with three equivalent Sn(1)S6 octahedra, edges with six equivalent Ca(3)S7 pentagonal bipyramids, and faces with two equivalent Ca(1)S6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 1°. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to three equivalent S(2) and six equivalent S(3) atoms. In the third Ca site, Ca(3) is bonded to one S(2), two equivalent S(1), and four equivalent S(3) atoms to form distorted CaS7 pentagonal bipyramids that share corners with two equivalent Sn(1)S6 octahedra, corners with two equivalent Ca(3)S7 pentagonal bipyramids, edges with four equivalent Sn(1)S6 octahedra, edges with two equivalent Ca(3)S7 pentagonal bipyramids, and edges with two equivalent Ca(1)S6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 51°. Sn(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form SnS6 octahedra that share corners with two equivalent Ca(3)S7 pentagonal bipyramids, corners with two equivalent Ca(1)S6 pentagonal pyramids, edges with two equivalent Sn(1)S6 octahedra, edges with four equivalent Ca(3)S7 pentagonal bipyramids, and  an edgeedge with one Ca(1)S6 pentagonal pyramid. There are three inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Ca(1), two equivalent Ca(3), and two equivalent Sn(1) atoms to form SCa4Sn2 octahedra that share corners with four equivalent S(1)Ca4Sn2 octahedra, corners with four equivalent S(2)Ca3Sn2 trigonal bipyramids, corners with four equivalent S(3)Ca4Sn trigonal bipyramids, edges with two equivalent S(1)Ca4Sn2 octahedra,  an edgeedge with one S(2)Ca3Sn2 trigonal bipyramid, edges with four equivalent S(3)Ca4Sn trigonal bipyramids, and faces with two equivalent S(1)Ca4Sn2 octahedra. The corner-sharing octahedral tilt angles are 42°. In the second S site, S(2) is bonded to one Ca(3), two equivalent Ca(2), and two equivalent Sn(1) atoms to form distorted SCa3Sn2 trigonal bipyramids that share corners with four equivalent S(1)Ca4Sn2 octahedra, corners with four equivalent S(3)Ca4Sn trigonal bipyramids, corners with six equivalent S(2)Ca3Sn2 trigonal bipyramids,  an edgeedge with one S(1)Ca4Sn2 octahedra, and edges with eight equivalent S(3)Ca4Sn trigonal bipyramids. The corner-sharing octahedral tilt angles range from 6-36°. In the third S site, S(3) is bonded to two equivalent Ca(2), two equivalent Ca(3), and one Sn(1) atom to form distorted SCa4Sn trigonal bipyramids that share corners with two equivalent S(1)Ca4Sn2 octahedra, corners with two equivalent S(2)Ca3Sn2 trigonal bipyramids, corners with seven equivalent S(3)Ca4Sn trigonal bipyramids, edges with two equivalent S(1)Ca4Sn2 octahedra, edges with four equivalent S(2)Ca3Sn2 trigonal bipyramids, and edges with five equivalent S(3)Ca4Sn trigonal bipyramids. The corner-sharing octahedral tilt angles are 54°.
Ca2SnS4 crystallizes in the hexagonal P-62m space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to six equivalent S(1) atoms to form distorted CaS6 pentagonal pyramids that share corners with six equivalent Sn(1)S6 octahedra, edges with three equivalent Sn(1)S6 octahedra, edges with six equivalent Ca(3)S7 pentagonal bipyramids, and faces with two equivalent Ca(1)S6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 1°. All Ca(1)-S(1) bond lengths are 2.83 Å. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to three equivalent S(2) and six equivalent S(3) atoms. All Ca(2)-S(2) bond lengths are 3.42 Å. All Ca(2)-S(3) bond lengths are 3.02 Å. In the third Ca site, Ca(3) is bonded to one S(2), two equivalent S(1), and four equivalent S(3) atoms to form distorted CaS7 pentagonal bipyramids that share corners with two equivalent Sn(1)S6 octahedra, corners with two equivalent Ca(3)S7 pentagonal bipyramids, edges with four equivalent Sn(1)S6 octahedra, edges with two equivalent Ca(3)S7 pentagonal bipyramids, and edges with two equivalent Ca(1)S6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 51°. The Ca(3)-S(2) bond length is 2.75 Å. Both Ca(3)-S(1) bond lengths are 3.00 Å. All Ca(3)-S(3) bond lengths are 2.89 Å. Sn(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form SnS6 octahedra that share corners with two equivalent Ca(3)S7 pentagonal bipyramids, corners with two equivalent Ca(1)S6 pentagonal pyramids, edges with two equivalent Sn(1)S6 octahedra, edges with four equivalent Ca(3)S7 pentagonal bipyramids, and  an edgeedge with one Ca(1)S6 pentagonal pyramid. Both Sn(1)-S(1) bond lengths are 2.78 Å. Both Sn(1)-S(2) bond lengths are 2.54 Å. Both Sn(1)-S(3) bond lengths are 2.51 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Ca(1), two equivalent Ca(3), and two equivalent Sn(1) atoms to form SCa4Sn2 octahedra that share corners with four equivalent S(1)Ca4Sn2 octahedra, corners with four equivalent S(2)Ca3Sn2 trigonal bipyramids, corners with four equivalent S(3)Ca4Sn trigonal bipyramids, edges with two equivalent S(1)Ca4Sn2 octahedra,  an edgeedge with one S(2)Ca3Sn2 trigonal bipyramid, edges with four equivalent S(3)Ca4Sn trigonal bipyramids, and faces with two equivalent S(1)Ca4Sn2 octahedra. The corner-sharing octahedral tilt angles are 42°. In the second S site, S(2) is bonded to one Ca(3), two equivalent Ca(2), and two equivalent Sn(1) atoms to form distorted SCa3Sn2 trigonal bipyramids that share corners with four equivalent S(1)Ca4Sn2 octahedra, corners with four equivalent S(3)Ca4Sn trigonal bipyramids, corners with six equivalent S(2)Ca3Sn2 trigonal bipyramids,  an edgeedge with one S(1)Ca4Sn2 octahedra, and edges with eight equivalent S(3)Ca4Sn trigonal bipyramids. The corner-sharing octahedral tilt angles range from 6-36°. In the third S site, S(3) is bonded to two equivalent Ca(2), two equivalent Ca(3), and one Sn(1) atom to form distorted SCa4Sn trigonal bipyramids that share corners with two equivalent S(1)Ca4Sn2 octahedra, corners with two equivalent S(2)Ca3Sn2 trigonal bipyramids, corners with seven equivalent S(3)Ca4Sn trigonal bipyramids, edges with two equivalent S(1)Ca4Sn2 octahedra, edges with four equivalent S(2)Ca3Sn2 trigonal bipyramids, and edges with five equivalent S(3)Ca4Sn trigonal bipyramids. The corner-sharing octahedral tilt angles are 54°.