CaSn2S5 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 4-coordinate geometry to four equivalent S(6) atoms. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one S(2), one S(4), two equivalent S(5), and three equivalent S(8) atoms. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one S(3), one S(6), one S(7), one S(8), and two equivalent S(2) atoms to form distorted SnS6 pentagonal pyramids that share corners with two equivalent Sn(1)S6 pentagonal pyramids,  a cornercorner with one S(5)Ca2Sn2S trigonal bipyramid, and edges with three equivalent Sn(2)S6 octahedra. In the second Sn site, Sn(2) is bonded to one S(2), one S(5), one S(7), and three equivalent S(3) atoms to form SnS6 octahedra that share corners with two equivalent Sn(2)S6 octahedra,  a cornercorner with one S(8)Ca3SnS trigonal bipyramid, edges with two equivalent Sn(2)S6 octahedra, and edges with three equivalent Sn(1)S6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 10°. In the third Sn site, Sn(3) is bonded in a 6-coordinate geometry to one S(1), one S(5), one S(6), one S(7), and two equivalent S(4) atoms. There are eight inequivalent S sites. In the first S site, S(1) is bonded in a linear geometry to two equivalent Sn(3) atoms. In the second S site, S(2) is bonded in a distorted see-saw-like geometry to one Ca(2), one Sn(2), and two equivalent Sn(1) atoms. In the third S site, S(3) is bonded in a rectangular see-saw-like geometry to one Sn(1) and three equivalent Sn(2) atoms. In the fourth S site, S(4) is bonded in a distorted T-shaped geometry to one Ca(2) and two equivalent Sn(3) atoms. In the fifth S site, S(5) is bonded to two equivalent Ca(2), one Sn(2), one Sn(3), and one S(8) atom to form distorted SCa2Sn2S trigonal bipyramids that share  a cornercorner with one Sn(1)S6 pentagonal pyramid,  a cornercorner with one S(6)Ca2Sn2 tetrahedra, corners with two equivalent S(5)Ca2Sn2S trigonal bipyramids, corners with four equivalent S(8)Ca3SnS trigonal bipyramids, and  an edgeedge with one S(8)Ca3SnS trigonal bipyramid. In the sixth S site, S(6) is bonded to two equivalent Ca(1), one Sn(1), and one Sn(3) atom to form distorted SCa2Sn2 tetrahedra that share corners with four equivalent S(6)Ca2Sn2 tetrahedra,  a cornercorner with one S(5)Ca2Sn2S trigonal bipyramid,  a cornercorner with one S(8)Ca3SnS trigonal bipyramid, and  an edgeedge with one S(6)Ca2Sn2 tetrahedra. In the seventh S site, S(7) is bonded in a distorted T-shaped geometry to one Sn(1), one Sn(2), and one Sn(3) atom. In the eighth S site, S(8) is bonded to three equivalent Ca(2), one Sn(1), and one S(5) atom to form distorted SCa3SnS trigonal bipyramids that share  a cornercorner with one Sn(2)S6 octahedra,  a cornercorner with one S(6)Ca2Sn2 tetrahedra, corners with two equivalent S(8)Ca3SnS trigonal bipyramids, corners with four equivalent S(5)Ca2Sn2S trigonal bipyramids,  an edgeedge with one S(5)Ca2Sn2S trigonal bipyramid, and edges with two equivalent S(8)Ca3SnS trigonal bipyramids. The corner-sharing octahedral tilt angles are 61°.
CaSn2S5 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 4-coordinate geometry to four equivalent S(6) atoms. All Ca(1)-S(6) bond lengths are 2.99 Å. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one S(2), one S(4), two equivalent S(5), and three equivalent S(8) atoms. The Ca(2)-S(2) bond length is 2.89 Å. The Ca(2)-S(4) bond length is 2.87 Å. Both Ca(2)-S(5) bond lengths are 2.85 Å. There are two shorter (3.13 Å) and one longer (3.37 Å) Ca(2)-S(8) bond length. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one S(3), one S(6), one S(7), one S(8), and two equivalent S(2) atoms to form distorted SnS6 pentagonal pyramids that share corners with two equivalent Sn(1)S6 pentagonal pyramids,  a cornercorner with one S(5)Ca2Sn2S trigonal bipyramid, and edges with three equivalent Sn(2)S6 octahedra. The Sn(1)-S(3) bond length is 2.67 Å. The Sn(1)-S(6) bond length is 2.66 Å. The Sn(1)-S(7) bond length is 2.76 Å. The Sn(1)-S(8) bond length is 2.82 Å. Both Sn(1)-S(2) bond lengths are 2.62 Å. In the second Sn site, Sn(2) is bonded to one S(2), one S(5), one S(7), and three equivalent S(3) atoms to form SnS6 octahedra that share corners with two equivalent Sn(2)S6 octahedra,  a cornercorner with one S(8)Ca3SnS trigonal bipyramid, edges with two equivalent Sn(2)S6 octahedra, and edges with three equivalent Sn(1)S6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 10°. The Sn(2)-S(2) bond length is 2.97 Å. The Sn(2)-S(5) bond length is 2.78 Å. The Sn(2)-S(7) bond length is 2.58 Å. There are two shorter (2.60 Å) and one longer (3.02 Å) Sn(2)-S(3) bond length. In the third Sn site, Sn(3) is bonded in a 6-coordinate geometry to one S(1), one S(5), one S(6), one S(7), and two equivalent S(4) atoms. The Sn(3)-S(1) bond length is 2.51 Å. The Sn(3)-S(5) bond length is 3.08 Å. The Sn(3)-S(6) bond length is 2.51 Å. The Sn(3)-S(7) bond length is 2.58 Å. Both Sn(3)-S(4) bond lengths are 2.64 Å. There are eight inequivalent S sites. In the first S site, S(1) is bonded in a linear geometry to two equivalent Sn(3) atoms. In the second S site, S(2) is bonded in a distorted see-saw-like geometry to one Ca(2), one Sn(2), and two equivalent Sn(1) atoms. In the third S site, S(3) is bonded in a rectangular see-saw-like geometry to one Sn(1) and three equivalent Sn(2) atoms. In the fourth S site, S(4) is bonded in a distorted T-shaped geometry to one Ca(2) and two equivalent Sn(3) atoms. In the fifth S site, S(5) is bonded to two equivalent Ca(2), one Sn(2), one Sn(3), and one S(8) atom to form distorted SCa2Sn2S trigonal bipyramids that share  a cornercorner with one Sn(1)S6 pentagonal pyramid,  a cornercorner with one S(6)Ca2Sn2 tetrahedra, corners with two equivalent S(5)Ca2Sn2S trigonal bipyramids, corners with four equivalent S(8)Ca3SnS trigonal bipyramids, and  an edgeedge with one S(8)Ca3SnS trigonal bipyramid. The S(5)-S(8) bond length is 2.08 Å. In the sixth S site, S(6) is bonded to two equivalent Ca(1), one Sn(1), and one Sn(3) atom to form distorted SCa2Sn2 tetrahedra that share corners with four equivalent S(6)Ca2Sn2 tetrahedra,  a cornercorner with one S(5)Ca2Sn2S trigonal bipyramid,  a cornercorner with one S(8)Ca3SnS trigonal bipyramid, and  an edgeedge with one S(6)Ca2Sn2 tetrahedra. In the seventh S site, S(7) is bonded in a distorted T-shaped geometry to one Sn(1), one Sn(2), and one Sn(3) atom. In the eighth S site, S(8) is bonded to three equivalent Ca(2), one Sn(1), and one S(5) atom to form distorted SCa3SnS trigonal bipyramids that share  a cornercorner with one Sn(2)S6 octahedra,  a cornercorner with one S(6)Ca2Sn2 tetrahedra, corners with two equivalent S(8)Ca3SnS trigonal bipyramids, corners with four equivalent S(5)Ca2Sn2S trigonal bipyramids,  an edgeedge with one S(5)Ca2Sn2S trigonal bipyramid, and edges with two equivalent S(8)Ca3SnS trigonal bipyramids. The corner-sharing octahedral tilt angles are 61°.