CsAsSe2 crystallizes in the orthorhombic Pbca space group. Cs(1) is bonded in a 10-coordinate geometry to two equivalent As(1), three equivalent Se(1), and five equivalent Se(2) atoms. As(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cs(1), one Se(2), and two equivalent Se(1) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to three equivalent Cs(1) and two equivalent As(1) atoms. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to five equivalent Cs(1) and one As(1) atom.
CsAsSe2 crystallizes in the orthorhombic Pbca space group. Cs(1) is bonded in a 10-coordinate geometry to two equivalent As(1), three equivalent Se(1), and five equivalent Se(2) atoms. Both Cs(1)-As(1) bond lengths are 3.92 Å. There are a spread of Cs(1)-Se(1) bond distances ranging from 3.74-4.04 Å. There are a spread of Cs(1)-Se(2) bond distances ranging from 3.74-3.83 Å. As(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cs(1), one Se(2), and two equivalent Se(1) atoms. The As(1)-Se(2) bond length is 2.32 Å. There is one shorter (2.45 Å) and one longer (2.46 Å) As(1)-Se(1) bond length. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to three equivalent Cs(1) and two equivalent As(1) atoms. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to five equivalent Cs(1) and one As(1) atom.