Cu2SeS3 crystallizes in the monoclinic Cc space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one S(1), one S(2), and two equivalent S(3) atoms to form corner-sharing CuS4 tetrahedra. In the second Cu site, Cu(2) is bonded to one S(1), one S(3), and two equivalent S(2) atoms to form corner-sharing CuS4 tetrahedra. Se(1) is bonded in a trigonal non-coplanar geometry to one S(1), one S(2), and one S(3) atom. There are three inequivalent S sites. In the first S site, S(1) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one Se(1) atom. In the second S site, S(2) is bonded to one Cu(1), two equivalent Cu(2), and one Se(1) atom to form distorted corner-sharing SCu3Se tetrahedra. In the third S site, S(3) is bonded to one Cu(2), two equivalent Cu(1), and one Se(1) atom to form distorted corner-sharing SCu3Se tetrahedra.
Cu2SeS3 crystallizes in the monoclinic Cc space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one S(1), one S(2), and two equivalent S(3) atoms to form corner-sharing CuS4 tetrahedra. The Cu(1)-S(1) bond length is 2.25 Å. The Cu(1)-S(2) bond length is 2.32 Å. There is one shorter (2.33 Å) and one longer (2.35 Å) Cu(1)-S(3) bond length. In the second Cu site, Cu(2) is bonded to one S(1), one S(3), and two equivalent S(2) atoms to form corner-sharing CuS4 tetrahedra. The Cu(2)-S(1) bond length is 2.33 Å. The Cu(2)-S(3) bond length is 2.31 Å. There is one shorter (2.32 Å) and one longer (2.36 Å) Cu(2)-S(2) bond length. Se(1) is bonded in a trigonal non-coplanar geometry to one S(1), one S(2), and one S(3) atom. The Se(1)-S(1) bond length is 2.22 Å. The Se(1)-S(2) bond length is 2.30 Å. The Se(1)-S(3) bond length is 2.33 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(2), and one Se(1) atom. In the second S site, S(2) is bonded to one Cu(1), two equivalent Cu(2), and one Se(1) atom to form distorted corner-sharing SCu3Se tetrahedra. In the third S site, S(3) is bonded to one Cu(2), two equivalent Cu(1), and one Se(1) atom to form distorted corner-sharing SCu3Se tetrahedra.