Cs2Cu2Sb2Se5 crystallizes in the triclinic P-1 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to one Cu(1), one Sb(1), one Se(1), one Se(2), one Se(5), two equivalent Se(3), and three equivalent Se(4) atoms. In the second Cs site, Cs(2) is bonded in a 8-coordinate geometry to one Se(3), one Se(4), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(5) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Cs(1), one Se(1), one Se(3), and two equivalent Se(5) atoms to form distorted CuCsSe4 tetrahedra that share corners with three equivalent Se(4)Cs4Sb2 octahedra and  an edgeedge with one Cu(1)CsSe4 tetrahedra. The corner-sharing octahedral tilt angles range from 25-93°. In the second Cu site, Cu(2) is bonded in a 4-coordinate geometry to one Se(2), one Se(5), and two equivalent Se(1) atoms. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a distorted trigonal non-coplanar geometry to one Cs(1), one Se(2), one Se(3), and one Se(4) atom. In the second Sb site, Sb(2) is bonded in a 3-coordinate geometry to one Se(1), one Se(3), one Se(4), and one Se(5) atom. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a 7-coordinate geometry to one Cs(1), two equivalent Cs(2), one Cu(1), two equivalent Cu(2), and one Sb(2) atom. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Cs(1), two equivalent Cs(2), one Cu(2), and one Sb(1) atom. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Cs(2), two equivalent Cs(1), one Cu(1), one Sb(1), and one Sb(2) atom. In the fourth Se site, Se(4) is bonded to one Cs(2), three equivalent Cs(1), one Sb(1), and one Sb(2) atom to form distorted SeCs4Sb2 octahedra that share corners with two equivalent Se(4)Cs4Sb2 octahedra, corners with three equivalent Cu(1)CsSe4 tetrahedra, and edges with two equivalent Se(4)Cs4Sb2 octahedra. The corner-sharing octahedral tilt angles are 3°. In the fifth Se site, Se(5) is bonded in a 7-coordinate geometry to one Cs(1), two equivalent Cs(2), one Cu(2), two equivalent Cu(1), and one Sb(2) atom.
Cs2Cu2Sb2Se5 crystallizes in the triclinic P-1 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to one Cu(1), one Sb(1), one Se(1), one Se(2), one Se(5), two equivalent Se(3), and three equivalent Se(4) atoms. The Cs(1)-Cu(1) bond length is 4.03 Å. The Cs(1)-Sb(1) bond length is 4.11 Å. The Cs(1)-Se(1) bond length is 3.75 Å. The Cs(1)-Se(2) bond length is 3.72 Å. The Cs(1)-Se(5) bond length is 4.09 Å. There is one shorter (3.70 Å) and one longer (3.89 Å) Cs(1)-Se(3) bond length. There are a spread of Cs(1)-Se(4) bond distances ranging from 3.75-4.01 Å. In the second Cs site, Cs(2) is bonded in a 8-coordinate geometry to one Se(3), one Se(4), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(5) atoms. The Cs(2)-Se(3) bond length is 3.60 Å. The Cs(2)-Se(4) bond length is 3.84 Å. There is one shorter (3.97 Å) and one longer (3.99 Å) Cs(2)-Se(1) bond length. There is one shorter (3.67 Å) and one longer (3.90 Å) Cs(2)-Se(2) bond length. There is one shorter (3.56 Å) and one longer (3.72 Å) Cs(2)-Se(5) bond length. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Cs(1), one Se(1), one Se(3), and two equivalent Se(5) atoms to form distorted CuCsSe4 tetrahedra that share corners with three equivalent Se(4)Cs4Sb2 octahedra and  an edgeedge with one Cu(1)CsSe4 tetrahedra. The corner-sharing octahedral tilt angles range from 25-93°. The Cu(1)-Se(1) bond length is 2.59 Å. The Cu(1)-Se(3) bond length is 2.44 Å. There is one shorter (2.51 Å) and one longer (2.52 Å) Cu(1)-Se(5) bond length. In the second Cu site, Cu(2) is bonded in a 4-coordinate geometry to one Se(2), one Se(5), and two equivalent Se(1) atoms. The Cu(2)-Se(2) bond length is 2.42 Å. The Cu(2)-Se(5) bond length is 2.67 Å. There is one shorter (2.55 Å) and one longer (2.58 Å) Cu(2)-Se(1) bond length. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a distorted trigonal non-coplanar geometry to one Cs(1), one Se(2), one Se(3), and one Se(4) atom. The Sb(1)-Se(2) bond length is 2.55 Å. The Sb(1)-Se(3) bond length is 2.58 Å. The Sb(1)-Se(4) bond length is 2.69 Å. In the second Sb site, Sb(2) is bonded in a 3-coordinate geometry to one Se(1), one Se(3), one Se(4), and one Se(5) atom. The Sb(2)-Se(1) bond length is 2.64 Å. The Sb(2)-Se(3) bond length is 3.30 Å. The Sb(2)-Se(4) bond length is 2.69 Å. The Sb(2)-Se(5) bond length is 2.64 Å. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a 7-coordinate geometry to one Cs(1), two equivalent Cs(2), one Cu(1), two equivalent Cu(2), and one Sb(2) atom. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Cs(1), two equivalent Cs(2), one Cu(2), and one Sb(1) atom. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Cs(2), two equivalent Cs(1), one Cu(1), one Sb(1), and one Sb(2) atom. In the fourth Se site, Se(4) is bonded to one Cs(2), three equivalent Cs(1), one Sb(1), and one Sb(2) atom to form distorted SeCs4Sb2 octahedra that share corners with two equivalent Se(4)Cs4Sb2 octahedra, corners with three equivalent Cu(1)CsSe4 tetrahedra, and edges with two equivalent Se(4)Cs4Sb2 octahedra. The corner-sharing octahedral tilt angles are 3°. In the fifth Se site, Se(5) is bonded in a 7-coordinate geometry to one Cs(1), two equivalent Cs(2), one Cu(2), two equivalent Cu(1), and one Sb(2) atom.