Eu2SnSe5 crystallizes in the orthorhombic Pbam space group. Eu(1) is bonded in a 9-coordinate geometry to two equivalent Se(1), three equivalent Se(3), and four equivalent Se(2) atoms. Sn(1) is bonded to two equivalent Se(2) and four equivalent Se(3) atoms to form edge-sharing SnSe6 octahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a square co-planar geometry to four equivalent Eu(1) atoms. In the second Se site, Se(2) is bonded to four equivalent Eu(1) and one Sn(1) atom to form a mixture of corner and edge-sharing SeEu4Sn square pyramids. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to three equivalent Eu(1) and two equivalent Sn(1) atoms.
Eu2SnSe5 crystallizes in the orthorhombic Pbam space group. Eu(1) is bonded in a 9-coordinate geometry to two equivalent Se(1), three equivalent Se(3), and four equivalent Se(2) atoms. Both Eu(1)-Se(1) bond lengths are 3.02 Å. There are a spread of Eu(1)-Se(3) bond distances ranging from 3.27-3.48 Å. There are two shorter (3.09 Å) and two longer (3.10 Å) Eu(1)-Se(2) bond lengths. Sn(1) is bonded to two equivalent Se(2) and four equivalent Se(3) atoms to form edge-sharing SnSe6 octahedra. Both Sn(1)-Se(2) bond lengths are 2.68 Å. All Sn(1)-Se(3) bond lengths are 2.75 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a square co-planar geometry to four equivalent Eu(1) atoms. In the second Se site, Se(2) is bonded to four equivalent Eu(1) and one Sn(1) atom to form a mixture of corner and edge-sharing SeEu4Sn square pyramids. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to three equivalent Eu(1) and two equivalent Sn(1) atoms.