Cs3(Cu4Se3)2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a distorted body-centered cubic geometry to four equivalent Se(1) and four equivalent Se(2) atoms. In the second Cs site, Cs(2) is bonded in a 7-coordinate geometry to two equivalent Se(1), two equivalent Se(2), and three equivalent Se(3) atoms. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(3) and three equivalent Se(1) atoms to form a mixture of distorted edge and corner-sharing CuSe4 tetrahedra. In the second Cu site, Cu(2) is bonded in a 4-coordinate geometry to one Se(1), one Se(2), and two equivalent Se(3) atoms. In the third Cu site, Cu(3) is bonded in a distorted trigonal planar geometry to one Se(3) and two equivalent Se(2) atoms. In the fourth Cu site, Cu(4) is bonded in a 3-coordinate geometry to one Se(2) and two equivalent Se(3) atoms. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 8-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), one Cu(2), and three equivalent Cu(1) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), one Cu(2), one Cu(4), and two equivalent Cu(3) atoms. In the third Se site, Se(3) is bonded in a 9-coordinate geometry to three equivalent Cs(2), one Cu(1), one Cu(3), two equivalent Cu(2), and two equivalent Cu(4) atoms.
Cs3(Cu4Se3)2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a distorted body-centered cubic geometry to four equivalent Se(1) and four equivalent Se(2) atoms. All Cs(1)-Se(1) bond lengths are 3.67 Å. All Cs(1)-Se(2) bond lengths are 3.64 Å. In the second Cs site, Cs(2) is bonded in a 7-coordinate geometry to two equivalent Se(1), two equivalent Se(2), and three equivalent Se(3) atoms. Both Cs(2)-Se(1) bond lengths are 3.57 Å. Both Cs(2)-Se(2) bond lengths are 3.64 Å. There are two shorter (3.59 Å) and one longer (3.88 Å) Cs(2)-Se(3) bond length. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(3) and three equivalent Se(1) atoms to form a mixture of distorted edge and corner-sharing CuSe4 tetrahedra. The Cu(1)-Se(3) bond length is 2.81 Å. There are two shorter (2.45 Å) and one longer (2.49 Å) Cu(1)-Se(1) bond length. In the second Cu site, Cu(2) is bonded in a 4-coordinate geometry to one Se(1), one Se(2), and two equivalent Se(3) atoms. The Cu(2)-Se(1) bond length is 2.38 Å. The Cu(2)-Se(2) bond length is 2.60 Å. Both Cu(2)-Se(3) bond lengths are 2.69 Å. In the third Cu site, Cu(3) is bonded in a distorted trigonal planar geometry to one Se(3) and two equivalent Se(2) atoms. The Cu(3)-Se(3) bond length is 2.44 Å. Both Cu(3)-Se(2) bond lengths are 2.43 Å. In the fourth Cu site, Cu(4) is bonded in a 3-coordinate geometry to one Se(2) and two equivalent Se(3) atoms. The Cu(4)-Se(2) bond length is 2.37 Å. Both Cu(4)-Se(3) bond lengths are 2.55 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 8-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), one Cu(2), and three equivalent Cu(1) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), one Cu(2), one Cu(4), and two equivalent Cu(3) atoms. In the third Se site, Se(3) is bonded in a 9-coordinate geometry to three equivalent Cs(2), one Cu(1), one Cu(3), two equivalent Cu(2), and two equivalent Cu(4) atoms.