CsPt2Se3 crystallizes in the trigonal R-3m space group. Cs(1) is bonded in a 12-coordinate geometry to three equivalent Pt(1) and nine equivalent Se(1) atoms. There are two inequivalent Pt sites. In the first Pt site, Pt(2) is bonded to six equivalent Se(1) atoms to form edge-sharing PtSe6 octahedra. In the second Pt site, Pt(1) is bonded to two equivalent Cs(1) and four equivalent Se(1) atoms to form distorted PtCs2Se4 octahedra that share edges with two equivalent Pt(2)Se6 octahedra and edges with four equivalent Pt(1)Cs2Se4 octahedra. Se(1) is bonded in a 6-coordinate geometry to three equivalent Cs(1), one Pt(2), and two equivalent Pt(1) atoms.
CsPt2Se3 crystallizes in the trigonal R-3m space group. Cs(1) is bonded in a 12-coordinate geometry to three equivalent Pt(1) and nine equivalent Se(1) atoms. All Cs(1)-Pt(1) bond lengths are 3.60 Å. There are three shorter (3.79 Å) and six longer (4.07 Å) Cs(1)-Se(1) bond lengths. There are two inequivalent Pt sites. In the first Pt site, Pt(2) is bonded to six equivalent Se(1) atoms to form edge-sharing PtSe6 octahedra. All Pt(2)-Se(1) bond lengths are 2.53 Å. In the second Pt site, Pt(1) is bonded to two equivalent Cs(1) and four equivalent Se(1) atoms to form distorted PtCs2Se4 octahedra that share edges with two equivalent Pt(2)Se6 octahedra and edges with four equivalent Pt(1)Cs2Se4 octahedra. All Pt(1)-Se(1) bond lengths are 2.46 Å. Se(1) is bonded in a 6-coordinate geometry to three equivalent Cs(1), one Pt(2), and two equivalent Pt(1) atoms.