CaSn2S5 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded to one S(1), one S(3), two equivalent S(2), and two equivalent S(4) atoms to form distorted CaS6 octahedra that share corners with two equivalent Ca(1)S6 octahedra, corners with two equivalent Sn(2)S5 trigonal bipyramids,  an edgeedge with one Ca(1)S6 octahedra, and  an edgeedge with one Sn(2)S5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 82°. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a distorted rectangular see-saw-like geometry to one S(1), one S(3), one S(4), and one S(5) atom. In the second Sn site, Sn(2) is bonded to one S(1), one S(3), one S(4), and two equivalent S(5) atoms to form SnS5 trigonal bipyramids that share corners with two equivalent Ca(1)S6 octahedra,  an edgeedge with one Ca(1)S6 octahedra, and  an edgeedge with one Sn(2)S5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 47-65°. There are five inequivalent S sites. In the first S site, S(1) is bonded in a 3-coordinate geometry to one Ca(1), one Sn(1), one Sn(2), and one S(2) atom. In the second S site, S(2) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one S(1), and one S(2) atom. In the third S site, S(3) is bonded in a distorted trigonal planar geometry to one Ca(1), one Sn(1), and one Sn(2) atom. In the fourth S site, S(4) is bonded to two equivalent Ca(1), one Sn(1), and one Sn(2) atom to form corner-sharing SCa2Sn2 tetrahedra. In the fifth S site, S(5) is bonded in a distorted L-shaped geometry to one Sn(1) and two equivalent Sn(2) atoms.
CaSn2S5 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded to one S(1), one S(3), two equivalent S(2), and two equivalent S(4) atoms to form distorted CaS6 octahedra that share corners with two equivalent Ca(1)S6 octahedra, corners with two equivalent Sn(2)S5 trigonal bipyramids,  an edgeedge with one Ca(1)S6 octahedra, and  an edgeedge with one Sn(2)S5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 82°. The Ca(1)-S(1) bond length is 2.88 Å. The Ca(1)-S(3) bond length is 2.71 Å. There is one shorter (2.71 Å) and one longer (2.89 Å) Ca(1)-S(2) bond length. There is one shorter (2.88 Å) and one longer (2.96 Å) Ca(1)-S(4) bond length. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a distorted rectangular see-saw-like geometry to one S(1), one S(3), one S(4), and one S(5) atom. The Sn(1)-S(1) bond length is 2.67 Å. The Sn(1)-S(3) bond length is 2.73 Å. The Sn(1)-S(4) bond length is 2.79 Å. The Sn(1)-S(5) bond length is 3.13 Å. In the second Sn site, Sn(2) is bonded to one S(1), one S(3), one S(4), and two equivalent S(5) atoms to form SnS5 trigonal bipyramids that share corners with two equivalent Ca(1)S6 octahedra,  an edgeedge with one Ca(1)S6 octahedra, and  an edgeedge with one Sn(2)S5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 47-65°. The Sn(2)-S(1) bond length is 2.71 Å. The Sn(2)-S(3) bond length is 2.43 Å. The Sn(2)-S(4) bond length is 2.49 Å. There is one shorter (2.47 Å) and one longer (2.59 Å) Sn(2)-S(5) bond length. There are five inequivalent S sites. In the first S site, S(1) is bonded in a 3-coordinate geometry to one Ca(1), one Sn(1), one Sn(2), and one S(2) atom. The S(1)-S(2) bond length is 2.41 Å. In the second S site, S(2) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one S(1), and one S(2) atom. The S(2)-S(2) bond length is 2.08 Å. In the third S site, S(3) is bonded in a distorted trigonal planar geometry to one Ca(1), one Sn(1), and one Sn(2) atom. In the fourth S site, S(4) is bonded to two equivalent Ca(1), one Sn(1), and one Sn(2) atom to form corner-sharing SCa2Sn2 tetrahedra. In the fifth S site, S(5) is bonded in a distorted L-shaped geometry to one Sn(1) and two equivalent Sn(2) atoms.