Eu3Sn2S7 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a body-centered cubic geometry to four equivalent S(2) and four equivalent S(3) atoms. In the second Eu site, Eu(2) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms. Sn(1) is bonded to one S(2), one S(3), one S(4), and two equivalent S(1) atoms to form corner-sharing SnS5 trigonal bipyramids. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted see-saw-like geometry to two equivalent Eu(2) and two equivalent Sn(1) atoms. In the second S site, S(2) is bonded to two equivalent Eu(1), two equivalent Eu(2), and one Sn(1) atom to form SEu4Sn square pyramids that share corners with two equivalent S(4)Eu4Sn2 octahedra, corners with two equivalent S(2)Eu4Sn square pyramids, corners with six equivalent S(3)Eu4Sn square pyramids, edges with two equivalent S(3)Eu4Sn square pyramids, edges with three equivalent S(2)Eu4Sn square pyramids,  a faceface with one S(4)Eu4Sn2 octahedra, and  a faceface with one S(3)Eu4Sn square pyramid. The corner-sharing octahedral tilt angles are 60°. In the third S site, S(3) is bonded to two equivalent Eu(1), two equivalent Eu(2), and one Sn(1) atom to form SEu4Sn square pyramids that share corners with three equivalent S(4)Eu4Sn2 octahedra, corners with two equivalent S(3)Eu4Sn square pyramids, corners with six equivalent S(2)Eu4Sn square pyramids,  an edgeedge with one S(4)Eu4Sn2 octahedra, edges with two equivalent S(2)Eu4Sn square pyramids, edges with three equivalent S(3)Eu4Sn square pyramids, and  a faceface with one S(2)Eu4Sn square pyramid. The corner-sharing octahedral tilt angles range from 9-34°. In the fourth S site, S(4) is bonded to four equivalent Eu(2) and two equivalent Sn(1) atoms to form SEu4Sn2 octahedra that share corners with four equivalent S(2)Eu4Sn square pyramids, corners with six equivalent S(3)Eu4Sn square pyramids, edges with two equivalent S(4)Eu4Sn2 octahedra, edges with two equivalent S(3)Eu4Sn square pyramids, and faces with two equivalent S(2)Eu4Sn square pyramids.
Eu3Sn2S7 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a body-centered cubic geometry to four equivalent S(2) and four equivalent S(3) atoms. All Eu(1)-S(2) bond lengths are 3.17 Å. All Eu(1)-S(3) bond lengths are 3.16 Å. In the second Eu site, Eu(2) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms. There is one shorter (3.07 Å) and one longer (3.21 Å) Eu(2)-S(1) bond length. Both Eu(2)-S(2) bond lengths are 3.04 Å. Both Eu(2)-S(3) bond lengths are 2.95 Å. Both Eu(2)-S(4) bond lengths are 3.08 Å. Sn(1) is bonded to one S(2), one S(3), one S(4), and two equivalent S(1) atoms to form corner-sharing SnS5 trigonal bipyramids. The Sn(1)-S(2) bond length is 2.43 Å. The Sn(1)-S(3) bond length is 2.49 Å. The Sn(1)-S(4) bond length is 2.76 Å. Both Sn(1)-S(1) bond lengths are 2.49 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted see-saw-like geometry to two equivalent Eu(2) and two equivalent Sn(1) atoms. In the second S site, S(2) is bonded to two equivalent Eu(1), two equivalent Eu(2), and one Sn(1) atom to form SEu4Sn square pyramids that share corners with two equivalent S(4)Eu4Sn2 octahedra, corners with two equivalent S(2)Eu4Sn square pyramids, corners with six equivalent S(3)Eu4Sn square pyramids, edges with two equivalent S(3)Eu4Sn square pyramids, edges with three equivalent S(2)Eu4Sn square pyramids,  a faceface with one S(4)Eu4Sn2 octahedra, and  a faceface with one S(3)Eu4Sn square pyramid. The corner-sharing octahedral tilt angles are 60°. In the third S site, S(3) is bonded to two equivalent Eu(1), two equivalent Eu(2), and one Sn(1) atom to form SEu4Sn square pyramids that share corners with three equivalent S(4)Eu4Sn2 octahedra, corners with two equivalent S(3)Eu4Sn square pyramids, corners with six equivalent S(2)Eu4Sn square pyramids,  an edgeedge with one S(4)Eu4Sn2 octahedra, edges with two equivalent S(2)Eu4Sn square pyramids, edges with three equivalent S(3)Eu4Sn square pyramids, and  a faceface with one S(2)Eu4Sn square pyramid. The corner-sharing octahedral tilt angles range from 9-34°. In the fourth S site, S(4) is bonded to four equivalent Eu(2) and two equivalent Sn(1) atoms to form SEu4Sn2 octahedra that share corners with four equivalent S(2)Eu4Sn square pyramids, corners with six equivalent S(3)Eu4Sn square pyramids, edges with two equivalent S(4)Eu4Sn2 octahedra, edges with two equivalent S(3)Eu4Sn square pyramids, and faces with two equivalent S(2)Eu4Sn square pyramids.