Sm3Tl5 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 9-coordinate geometry to one Tl(1), four equivalent Tl(2), and four equivalent Tl(3) atoms. In the second Sm site, Sm(2) is bonded in a 10-coordinate geometry to two equivalent Tl(1), four equivalent Tl(2), and four equivalent Tl(3) atoms. There are three inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 11-coordinate geometry to one Sm(1), four equivalent Sm(2), two equivalent Tl(2), and four equivalent Tl(3) atoms. In the second Tl site, Tl(2) is bonded in a 10-coordinate geometry to two equivalent Sm(1), four equivalent Sm(2), one Tl(1), one Tl(2), and two equivalent Tl(3) atoms. In the third Tl site, Tl(3) is bonded in a 10-coordinate geometry to two equivalent Sm(1), four equivalent Sm(2), two equivalent Tl(1), and two equivalent Tl(2) atoms.
Sm3Tl5 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 9-coordinate geometry to one Tl(1), four equivalent Tl(2), and four equivalent Tl(3) atoms. The Sm(1)-Tl(1) bond length is 3.13 Å. There are two shorter (3.21 Å) and two longer (3.39 Å) Sm(1)-Tl(2) bond lengths. There are two shorter (3.14 Å) and two longer (3.68 Å) Sm(1)-Tl(3) bond lengths. In the second Sm site, Sm(2) is bonded in a 10-coordinate geometry to two equivalent Tl(1), four equivalent Tl(2), and four equivalent Tl(3) atoms. Both Sm(2)-Tl(1) bond lengths are 3.37 Å. There are two shorter (3.34 Å) and two longer (3.53 Å) Sm(2)-Tl(2) bond lengths. There are two shorter (3.27 Å) and two longer (3.55 Å) Sm(2)-Tl(3) bond lengths. There are three inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 11-coordinate geometry to one Sm(1), four equivalent Sm(2), two equivalent Tl(2), and four equivalent Tl(3) atoms. Both Tl(1)-Tl(2) bond lengths are 3.28 Å. There are two shorter (3.32 Å) and two longer (3.37 Å) Tl(1)-Tl(3) bond lengths. In the second Tl site, Tl(2) is bonded in a 10-coordinate geometry to two equivalent Sm(1), four equivalent Sm(2), one Tl(1), one Tl(2), and two equivalent Tl(3) atoms. The Tl(2)-Tl(2) bond length is 3.38 Å. Both Tl(2)-Tl(3) bond lengths are 3.17 Å. In the third Tl site, Tl(3) is bonded in a 10-coordinate geometry to two equivalent Sm(1), four equivalent Sm(2), two equivalent Tl(1), and two equivalent Tl(2) atoms.