Tl4SnSe3 crystallizes in the tetragonal I4/mcm space group. Tl(1) is bonded in a distorted single-bond geometry to three equivalent Se(2) atoms. Sn(1) is bonded to two equivalent Se(1) and four equivalent Se(2) atoms to form corner-sharing SnSe6 octahedra. The corner-sharing octahedral tilt angles range from 0-38°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted linear geometry to two equivalent Sn(1) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to six equivalent Tl(1) and two equivalent Sn(1) atoms.
Tl4SnSe3 crystallizes in the tetragonal I4/mcm space group. Tl(1) is bonded in a distorted single-bond geometry to three equivalent Se(2) atoms. There is one shorter (3.00 Å) and two longer (3.35 Å) Tl(1)-Se(2) bond lengths. Sn(1) is bonded to two equivalent Se(1) and four equivalent Se(2) atoms to form corner-sharing SnSe6 octahedra. The corner-sharing octahedral tilt angles range from 0-38°. Both Sn(1)-Se(1) bond lengths are 3.23 Å. All Sn(1)-Se(2) bond lengths are 3.18 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted linear geometry to two equivalent Sn(1) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to six equivalent Tl(1) and two equivalent Sn(1) atoms.