TlCu4Se3 is Hazelwoodite-derived structured and crystallizes in the orthorhombic Pnnm space group. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 8-coordinate geometry to one Cu(1), one Cu(2), two equivalent Cu(3), two equivalent Se(2), and two equivalent Se(3) atoms. In the second Cu site, Cu(2) is bonded in a 4-coordinate geometry to one Cu(1), one Se(1), one Se(3), and two equivalent Se(2) atoms. In the third Cu site, Cu(3) is bonded to two equivalent Cu(1), one Se(1), one Se(2), and two equivalent Se(3) atoms to form distorted CuCu2Se4 tetrahedra that share  a cornercorner with one Cu(4)Se4 tetrahedra, edges with two equivalent Cu(3)Cu2Se4 tetrahedra, and edges with two equivalent Cu(4)Se4 tetrahedra. In the fourth Cu site, Cu(4) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form distorted CuSe4 tetrahedra that share  a cornercorner with one Cu(3)Cu2Se4 tetrahedra, corners with two equivalent Cu(4)Se4 tetrahedra, and edges with two equivalent Cu(3)Cu2Se4 tetrahedra. Tl(1) is bonded in a 2-coordinate geometry to two equivalent Se(2) atoms. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Cu(2), one Cu(3), and two equivalent Cu(4) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to one Cu(3), one Cu(4), two equivalent Cu(1), two equivalent Cu(2), and two equivalent Tl(1) atoms. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Cu(2), one Cu(4), two equivalent Cu(1), and two equivalent Cu(3) atoms.
TlCu4Se3 is Hazelwoodite-derived structured and crystallizes in the orthorhombic Pnnm space group. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 8-coordinate geometry to one Cu(1), one Cu(2), two equivalent Cu(3), two equivalent Se(2), and two equivalent Se(3) atoms. The Cu(1)-Cu(1) bond length is 2.63 Å. The Cu(1)-Cu(2) bond length is 2.47 Å. Both Cu(1)-Cu(3) bond lengths are 2.74 Å. Both Cu(1)-Se(2) bond lengths are 2.53 Å. There is one shorter (2.38 Å) and one longer (2.73 Å) Cu(1)-Se(3) bond length. In the second Cu site, Cu(2) is bonded in a 4-coordinate geometry to one Cu(1), one Se(1), one Se(3), and two equivalent Se(2) atoms. The Cu(2)-Se(1) bond length is 2.37 Å. The Cu(2)-Se(3) bond length is 2.50 Å. Both Cu(2)-Se(2) bond lengths are 2.62 Å. In the third Cu site, Cu(3) is bonded to two equivalent Cu(1), one Se(1), one Se(2), and two equivalent Se(3) atoms to form distorted CuCu2Se4 tetrahedra that share  a cornercorner with one Cu(4)Se4 tetrahedra, edges with two equivalent Cu(3)Cu2Se4 tetrahedra, and edges with two equivalent Cu(4)Se4 tetrahedra. The Cu(3)-Se(1) bond length is 2.46 Å. The Cu(3)-Se(2) bond length is 2.74 Å. Both Cu(3)-Se(3) bond lengths are 2.43 Å. In the fourth Cu site, Cu(4) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form distorted CuSe4 tetrahedra that share  a cornercorner with one Cu(3)Cu2Se4 tetrahedra, corners with two equivalent Cu(4)Se4 tetrahedra, and edges with two equivalent Cu(3)Cu2Se4 tetrahedra. The Cu(4)-Se(2) bond length is 2.52 Å. The Cu(4)-Se(3) bond length is 2.69 Å. Both Cu(4)-Se(1) bond lengths are 2.44 Å. Tl(1) is bonded in a 2-coordinate geometry to two equivalent Se(2) atoms. Both Tl(1)-Se(2) bond lengths are 3.35 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Cu(2), one Cu(3), and two equivalent Cu(4) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to one Cu(3), one Cu(4), two equivalent Cu(1), two equivalent Cu(2), and two equivalent Tl(1) atoms. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Cu(2), one Cu(4), two equivalent Cu(1), and two equivalent Cu(3) atoms.