TaCu3TeSe2S crystallizes in the monoclinic Cm space group. Ta(1) is bonded in a 10-coordinate geometry to two equivalent Cu(1), four equivalent Cu(2), one Te(1), two equivalent Se(1), and one S(1) atom. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 6-coordinate geometry to two equivalent Ta(1), one Te(1), two equivalent Se(1), and one S(1) atom. In the second Cu site, Cu(2) is bonded in a 6-coordinate geometry to two equivalent Ta(1), one Te(1), two equivalent Se(1), and one S(1) atom. Te(1) is bonded to one Ta(1), one Cu(1), and two equivalent Cu(2) atoms to form distorted TeTaCu3 tetrahedra that share corners with two equivalent S(1)TaCu3 tetrahedra, corners with four equivalent Se(1)TaCu3 tetrahedra,  an edgeedge with one S(1)TaCu3 tetrahedra, and edges with two equivalent Se(1)TaCu3 tetrahedra. Se(1) is bonded to one Ta(1), one Cu(1), and two equivalent Cu(2) atoms to form SeTaCu3 tetrahedra that share corners with two equivalent Te(1)TaCu3 tetrahedra, corners with two equivalent Se(1)TaCu3 tetrahedra, corners with two equivalent S(1)TaCu3 tetrahedra,  an edgeedge with one Te(1)TaCu3 tetrahedra,  an edgeedge with one Se(1)TaCu3 tetrahedra, and  an edgeedge with one S(1)TaCu3 tetrahedra. S(1) is bonded to one Ta(1), one Cu(1), and two equivalent Cu(2) atoms to form distorted STaCu3 tetrahedra that share corners with two equivalent Te(1)TaCu3 tetrahedra, corners with four equivalent Se(1)TaCu3 tetrahedra,  an edgeedge with one Te(1)TaCu3 tetrahedra, and edges with two equivalent Se(1)TaCu3 tetrahedra.
TaCu3TeSe2S crystallizes in the monoclinic Cm space group. Ta(1) is bonded in a 10-coordinate geometry to two equivalent Cu(1), four equivalent Cu(2), one Te(1), two equivalent Se(1), and one S(1) atom. There is one shorter (2.88 Å) and one longer (2.89 Å) Ta(1)-Cu(1) bond length. There are two shorter (2.84 Å) and two longer (2.93 Å) Ta(1)-Cu(2) bond lengths. The Ta(1)-Te(1) bond length is 2.66 Å. Both Ta(1)-Se(1) bond lengths are 2.46 Å. The Ta(1)-S(1) bond length is 2.33 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 6-coordinate geometry to two equivalent Ta(1), one Te(1), two equivalent Se(1), and one S(1) atom. The Cu(1)-Te(1) bond length is 2.66 Å. Both Cu(1)-Se(1) bond lengths are 2.49 Å. The Cu(1)-S(1) bond length is 2.36 Å. In the second Cu site, Cu(2) is bonded in a 6-coordinate geometry to two equivalent Ta(1), one Te(1), two equivalent Se(1), and one S(1) atom. The Cu(2)-Te(1) bond length is 2.63 Å. There is one shorter (2.47 Å) and one longer (2.51 Å) Cu(2)-Se(1) bond length. The Cu(2)-S(1) bond length is 2.37 Å. Te(1) is bonded to one Ta(1), one Cu(1), and two equivalent Cu(2) atoms to form distorted TeTaCu3 tetrahedra that share corners with two equivalent S(1)TaCu3 tetrahedra, corners with four equivalent Se(1)TaCu3 tetrahedra,  an edgeedge with one S(1)TaCu3 tetrahedra, and edges with two equivalent Se(1)TaCu3 tetrahedra. Se(1) is bonded to one Ta(1), one Cu(1), and two equivalent Cu(2) atoms to form SeTaCu3 tetrahedra that share corners with two equivalent Te(1)TaCu3 tetrahedra, corners with two equivalent Se(1)TaCu3 tetrahedra, corners with two equivalent S(1)TaCu3 tetrahedra,  an edgeedge with one Te(1)TaCu3 tetrahedra,  an edgeedge with one Se(1)TaCu3 tetrahedra, and  an edgeedge with one S(1)TaCu3 tetrahedra. S(1) is bonded to one Ta(1), one Cu(1), and two equivalent Cu(2) atoms to form distorted STaCu3 tetrahedra that share corners with two equivalent Te(1)TaCu3 tetrahedra, corners with four equivalent Se(1)TaCu3 tetrahedra,  an edgeedge with one Te(1)TaCu3 tetrahedra, and edges with two equivalent Se(1)TaCu3 tetrahedra.