Cs3GeAsSe5 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 9-coordinate geometry to one As(1), one Se(1), one Se(3), two equivalent Se(2), two equivalent Se(4), and two equivalent Se(5) atoms. In the second Cs site, Cs(2) is bonded in a 6-coordinate geometry to one Se(1), one Se(4), two equivalent Se(3), and two equivalent Se(5) atoms. In the third Cs site, Cs(3) is bonded in a 7-coordinate geometry to one Se(2), one Se(4), one Se(5), two equivalent Se(1), and two equivalent Se(3) atoms. Ge(1) is bonded in a tetrahedral geometry to one Se(1), one Se(2), one Se(3), and one Se(4) atom. As(1) is bonded in a 3-coordinate geometry to one Cs(1), one Se(2), 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 1-coordinate geometry to one Cs(1), one Cs(2), two equivalent Cs(3), and one Ge(1) atom. In the second Se site, Se(2) is bonded in a 2-coordinate geometry to one Cs(3), two equivalent Cs(1), one Ge(1), and one As(1) atom. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Cs(1), two equivalent Cs(2), two equivalent Cs(3), and one Ge(1) atom. In the fourth Se site, Se(4) is bonded to one Cs(2), one Cs(3), two equivalent Cs(1), one Ge(1), and one As(1) atom to form distorted SeCs4GeAs octahedra that share  a cornercorner with one Se(5)Cs5As octahedra, corners with two equivalent Se(4)Cs4GeAs octahedra, edges with two equivalent Se(5)Cs5As octahedra, and  a faceface with one Se(5)Cs5As octahedra. The corner-sharing octahedral tilt angles range from 26-48°. In the fifth Se site, Se(5) is bonded to one Cs(3), two equivalent Cs(1), two equivalent Cs(2), and one As(1) atom to form distorted SeCs5As octahedra that share  a cornercorner with one Se(4)Cs4GeAs octahedra, corners with two equivalent Se(5)Cs5As octahedra,  an edgeedge with one Se(5)Cs5As octahedra, edges with two equivalent Se(4)Cs4GeAs octahedra, and  a faceface with one Se(4)Cs4GeAs octahedra. The corner-sharing octahedral tilt angles range from 26-47°.
Cs3GeAsSe5 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 9-coordinate geometry to one As(1), one Se(1), one Se(3), two equivalent Se(2), two equivalent Se(4), and two equivalent Se(5) atoms. The Cs(1)-As(1) bond length is 4.11 Å. The Cs(1)-Se(1) bond length is 4.25 Å. The Cs(1)-Se(3) bond length is 3.79 Å. There is one shorter (3.70 Å) and one longer (4.12 Å) Cs(1)-Se(2) bond length. There is one shorter (3.62 Å) and one longer (3.87 Å) Cs(1)-Se(4) bond length. There is one shorter (3.78 Å) and one longer (3.79 Å) Cs(1)-Se(5) bond length. In the second Cs site, Cs(2) is bonded in a 6-coordinate geometry to one Se(1), one Se(4), two equivalent Se(3), and two equivalent Se(5) atoms. The Cs(2)-Se(1) bond length is 3.76 Å. The Cs(2)-Se(4) bond length is 4.05 Å. There is one shorter (3.65 Å) and one longer (4.09 Å) Cs(2)-Se(3) bond length. There is one shorter (3.70 Å) and one longer (3.76 Å) Cs(2)-Se(5) bond length. In the third Cs site, Cs(3) is bonded in a 7-coordinate geometry to one Se(2), one Se(4), one Se(5), two equivalent Se(1), and two equivalent Se(3) atoms. The Cs(3)-Se(2) bond length is 3.79 Å. The Cs(3)-Se(4) bond length is 3.76 Å. The Cs(3)-Se(5) bond length is 3.84 Å. There is one shorter (3.66 Å) and one longer (3.94 Å) Cs(3)-Se(1) bond length. There is one shorter (3.78 Å) and one longer (3.91 Å) Cs(3)-Se(3) bond length. Ge(1) is bonded in a tetrahedral geometry to one Se(1), one Se(2), one Se(3), and one Se(4) atom. The Ge(1)-Se(1) bond length is 2.33 Å. The Ge(1)-Se(2) bond length is 2.48 Å. The Ge(1)-Se(3) bond length is 2.33 Å. The Ge(1)-Se(4) bond length is 2.48 Å. As(1) is bonded in a 3-coordinate geometry to one Cs(1), one Se(2), one Se(4), and one Se(5) atom. The As(1)-Se(2) bond length is 2.50 Å. The As(1)-Se(4) bond length is 2.52 Å. The As(1)-Se(5) bond length is 2.35 Å. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a 1-coordinate geometry to one Cs(1), one Cs(2), two equivalent Cs(3), and one Ge(1) atom. In the second Se site, Se(2) is bonded in a 2-coordinate geometry to one Cs(3), two equivalent Cs(1), one Ge(1), and one As(1) atom. In the third Se site, Se(3) is bonded in a 6-coordinate geometry to one Cs(1), two equivalent Cs(2), two equivalent Cs(3), and one Ge(1) atom. In the fourth Se site, Se(4) is bonded to one Cs(2), one Cs(3), two equivalent Cs(1), one Ge(1), and one As(1) atom to form distorted SeCs4GeAs octahedra that share  a cornercorner with one Se(5)Cs5As octahedra, corners with two equivalent Se(4)Cs4GeAs octahedra, edges with two equivalent Se(5)Cs5As octahedra, and  a faceface with one Se(5)Cs5As octahedra. The corner-sharing octahedral tilt angles range from 26-48°. In the fifth Se site, Se(5) is bonded to one Cs(3), two equivalent Cs(1), two equivalent Cs(2), and one As(1) atom to form distorted SeCs5As octahedra that share  a cornercorner with one Se(4)Cs4GeAs octahedra, corners with two equivalent Se(5)Cs5As octahedra,  an edgeedge with one Se(5)Cs5As octahedra, edges with two equivalent Se(4)Cs4GeAs octahedra, and  a faceface with one Se(4)Cs4GeAs octahedra. The corner-sharing octahedral tilt angles range from 26-47°.