Ca3Sn2S7 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one S(3), one S(6), one S(7), and two equivalent S(2) atoms. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one S(3), one S(4), one S(7), two equivalent S(1), and two equivalent S(5) atoms. In the third Ca site, Ca(3) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(3), one S(5), one S(6), and one S(7) atom. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a tetrahedral geometry to one S(4), one S(5), one S(6), and one S(7) atom. In the second Sn site, Sn(2) is bonded in a 4-coordinate geometry to one S(1), one S(2), one S(3), one S(4), and one S(7) atom. There are seven inequivalent S sites. In the first S site, S(4) is bonded in a 3-coordinate geometry to one Ca(2), one Sn(1), and one Sn(2) atom. In the second S site, S(5) is bonded in a distorted rectangular see-saw-like geometry to one Ca(3), two equivalent Ca(2), and one Sn(1) atom. In the third S site, S(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(3), and one Sn(1) atom. In the fourth S site, S(7) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Sn(1), and one Sn(2) atom. In the fifth S site, S(1) is bonded to one Ca(3), two equivalent Ca(2), and one Sn(2) atom to form a mixture of distorted edge and corner-sharing SCa3Sn trigonal pyramids. In the sixth S site, S(2) is bonded to one Ca(3), two equivalent Ca(1), and one Sn(2) atom to form a mixture of distorted edge and corner-sharing SCa3Sn trigonal pyramids. In the seventh S site, S(3) is bonded to one Ca(1), one Ca(2), one Ca(3), and one Sn(2) atom to form a mixture of edge and corner-sharing SCa3Sn tetrahedra.
Ca3Sn2S7 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one S(3), one S(6), one S(7), and two equivalent S(2) atoms. The Ca(1)-S(3) bond length is 2.96 Å. The Ca(1)-S(6) bond length is 3.02 Å. The Ca(1)-S(7) bond length is 2.92 Å. There is one shorter (2.86 Å) and one longer (2.96 Å) Ca(1)-S(2) bond length. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one S(3), one S(4), one S(7), two equivalent S(1), and two equivalent S(5) atoms. The Ca(2)-S(3) bond length is 2.80 Å. The Ca(2)-S(4) bond length is 3.04 Å. The Ca(2)-S(7) bond length is 3.07 Å. There is one shorter (2.90 Å) and one longer (2.97 Å) Ca(2)-S(1) bond length. There is one shorter (2.87 Å) and one longer (3.32 Å) Ca(2)-S(5) bond length. In the third Ca site, Ca(3) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(3), one S(5), one S(6), and one S(7) atom. The Ca(3)-S(1) bond length is 2.93 Å. The Ca(3)-S(2) bond length is 2.90 Å. The Ca(3)-S(3) bond length is 2.93 Å. The Ca(3)-S(5) bond length is 2.92 Å. The Ca(3)-S(6) bond length is 3.09 Å. The Ca(3)-S(7) bond length is 2.80 Å. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a tetrahedral geometry to one S(4), one S(5), one S(6), and one S(7) atom. The Sn(1)-S(4) bond length is 2.46 Å. The Sn(1)-S(5) bond length is 2.41 Å. The Sn(1)-S(6) bond length is 2.38 Å. The Sn(1)-S(7) bond length is 2.44 Å. In the second Sn site, Sn(2) is bonded in a 4-coordinate geometry to one S(1), one S(2), one S(3), one S(4), and one S(7) atom. The Sn(2)-S(1) bond length is 2.41 Å. The Sn(2)-S(2) bond length is 2.41 Å. The Sn(2)-S(3) bond length is 2.41 Å. The Sn(2)-S(4) bond length is 2.51 Å. The Sn(2)-S(7) bond length is 3.11 Å. There are seven inequivalent S sites. In the first S site, S(4) is bonded in a 3-coordinate geometry to one Ca(2), one Sn(1), and one Sn(2) atom. In the second S site, S(5) is bonded in a distorted rectangular see-saw-like geometry to one Ca(3), two equivalent Ca(2), and one Sn(1) atom. In the third S site, S(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(3), and one Sn(1) atom. In the fourth S site, S(7) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Sn(1), and one Sn(2) atom. In the fifth S site, S(1) is bonded to one Ca(3), two equivalent Ca(2), and one Sn(2) atom to form a mixture of distorted edge and corner-sharing SCa3Sn trigonal pyramids. In the sixth S site, S(2) is bonded to one Ca(3), two equivalent Ca(1), and one Sn(2) atom to form a mixture of distorted edge and corner-sharing SCa3Sn trigonal pyramids. In the seventh S site, S(3) is bonded to one Ca(1), one Ca(2), one Ca(3), and one Sn(2) atom to form a mixture of edge and corner-sharing SCa3Sn tetrahedra.