Cu3SbSe4 crystallizes in the trigonal R3m space group. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(1) and three equivalent Se(4) atoms to form corner-sharing CuSe4 tetrahedra. In the second Cu site, Cu(2) is bonded to one Se(2) and three equivalent Se(1) atoms to form corner-sharing CuSe4 tetrahedra. In the third Cu site, Cu(3) is bonded to one Se(3) and three equivalent Se(2) atoms to form corner-sharing CuSe4 tetrahedra. Sb(1) is bonded in a rectangular see-saw-like geometry to one Se(4) and three equivalent Se(3) atoms. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one Cu(1) and three equivalent Cu(2) atoms to form SeCu4 tetrahedra that share corners with three equivalent Se(4)Cu3Sb tetrahedra, corners with three equivalent Se(2)Cu4 tetrahedra, and corners with six equivalent Se(1)Cu4 tetrahedra. In the second Se site, Se(2) is bonded to one Cu(2) and three equivalent Cu(3) atoms to form corner-sharing SeCu4 tetrahedra. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Cu(3) and three equivalent Sb(1) atoms. In the fourth Se site, Se(4) is bonded to three equivalent Cu(1) and one Sb(1) atom to form SeCu3Sb tetrahedra that share corners with three equivalent Se(1)Cu4 tetrahedra and corners with six equivalent Se(4)Cu3Sb tetrahedra.
Cu3SbSe4 crystallizes in the trigonal R3m space group. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(1) and three equivalent Se(4) atoms to form corner-sharing CuSe4 tetrahedra. The Cu(1)-Se(1) bond length is 2.38 Å. All Cu(1)-Se(4) bond lengths are 2.38 Å. In the second Cu site, Cu(2) is bonded to one Se(2) and three equivalent Se(1) atoms to form corner-sharing CuSe4 tetrahedra. The Cu(2)-Se(2) bond length is 2.41 Å. All Cu(2)-Se(1) bond lengths are 2.42 Å. In the third Cu site, Cu(3) is bonded to one Se(3) and three equivalent Se(2) atoms to form corner-sharing CuSe4 tetrahedra. The Cu(3)-Se(3) bond length is 2.48 Å. All Cu(3)-Se(2) bond lengths are 2.36 Å. Sb(1) is bonded in a rectangular see-saw-like geometry to one Se(4) and three equivalent Se(3) atoms. The Sb(1)-Se(4) bond length is 2.75 Å. All Sb(1)-Se(3) bond lengths are 2.86 Å. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one Cu(1) and three equivalent Cu(2) atoms to form SeCu4 tetrahedra that share corners with three equivalent Se(4)Cu3Sb tetrahedra, corners with three equivalent Se(2)Cu4 tetrahedra, and corners with six equivalent Se(1)Cu4 tetrahedra. In the second Se site, Se(2) is bonded to one Cu(2) and three equivalent Cu(3) atoms to form corner-sharing SeCu4 tetrahedra. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Cu(3) and three equivalent Sb(1) atoms. In the fourth Se site, Se(4) is bonded to three equivalent Cu(1) and one Sb(1) atom to form SeCu3Sb tetrahedra that share corners with three equivalent Se(1)Cu4 tetrahedra and corners with six equivalent Se(4)Cu3Sb tetrahedra.