Cs2Ni3Se4 crystallizes in the orthorhombic Fmmm space group. Cs(1) is bonded in a 8-coordinate geometry to eight equivalent Se(1) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a square co-planar geometry to four equivalent Se(1) atoms. In the second Ni site, Ni(2) is bonded in a square co-planar geometry to four equivalent Se(1) atoms. Se(1) is bonded in a 3-coordinate geometry to four equivalent Cs(1), one Ni(2), and two equivalent Ni(1) atoms.
Cs2Ni3Se4 crystallizes in the orthorhombic Fmmm space group. Cs(1) is bonded in a 8-coordinate geometry to eight equivalent Se(1) atoms. There are a spread of Cs(1)-Se(1) bond distances ranging from 3.62-3.94 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a square co-planar geometry to four equivalent Se(1) atoms. All Ni(1)-Se(1) bond lengths are 2.34 Å. In the second Ni site, Ni(2) is bonded in a square co-planar geometry to four equivalent Se(1) atoms. All Ni(2)-Se(1) bond lengths are 2.33 Å. Se(1) is bonded in a 3-coordinate geometry to four equivalent Cs(1), one Ni(2), and two equivalent Ni(1) atoms.