Ca2SnS4 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 4-coordinate geometry to one S(1) and three equivalent S(2) atoms. In the second Ca site, Ca(2) is bonded to six equivalent S(2) atoms to form CaS6 octahedra that share corners with six equivalent Sn(1)S4 tetrahedra and faces with two equivalent Ca(2)S6 octahedra. Sn(1) is bonded to one S(1) and three equivalent S(2) atoms to form distorted SnS4 tetrahedra that share corners with six equivalent Ca(2)S6 octahedra. The corner-sharing octahedral tilt angles range from 16-68°. There are two inequivalent S sites. In the first S site, S(1) is bonded in a linear geometry to one Ca(1) and one Sn(1) atom. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to one Ca(1), two equivalent Ca(2), and one Sn(1) atom.
Ca2SnS4 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 4-coordinate geometry to one S(1) and three equivalent S(2) atoms. The Ca(1)-S(1) bond length is 2.54 Å. All Ca(1)-S(2) bond lengths are 2.94 Å. In the second Ca site, Ca(2) is bonded to six equivalent S(2) atoms to form CaS6 octahedra that share corners with six equivalent Sn(1)S4 tetrahedra and faces with two equivalent Ca(2)S6 octahedra. There are three shorter (2.90 Å) and three longer (2.95 Å) Ca(2)-S(2) bond lengths. Sn(1) is bonded to one S(1) and three equivalent S(2) atoms to form distorted SnS4 tetrahedra that share corners with six equivalent Ca(2)S6 octahedra. The corner-sharing octahedral tilt angles range from 16-68°. The Sn(1)-S(1) bond length is 2.26 Å. All Sn(1)-S(2) bond lengths are 2.44 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded in a linear geometry to one Ca(1) and one Sn(1) atom. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to one Ca(1), two equivalent Ca(2), and one Sn(1) atom.