CsSnSe3 crystallizes in the triclinic P-1 space group. Cs(1) is bonded in a 7-coordinate geometry to two equivalent Se(1), two equivalent Se(3), and three equivalent Se(2) atoms. Sn(1) is bonded to one Se(2), two equivalent Se(1), and two equivalent Se(3) atoms to form edge-sharing SnSe5 trigonal bipyramids. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to two equivalent Cs(1) and two equivalent Sn(1) atoms. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to three equivalent Cs(1), one Sn(1), and one Se(2) atom. In the third Se site, Se(3) is bonded in a 4-coordinate geometry to two equivalent Cs(1) and two equivalent Sn(1) atoms.
CsSnSe3 crystallizes in the triclinic P-1 space group. Cs(1) is bonded in a 7-coordinate geometry to two equivalent Se(1), two equivalent Se(3), and three equivalent Se(2) atoms. There is one shorter (3.83 Å) and one longer (3.89 Å) Cs(1)-Se(1) bond length. There is one shorter (3.76 Å) and one longer (3.84 Å) Cs(1)-Se(3) bond length. There are a spread of Cs(1)-Se(2) bond distances ranging from 3.75-4.02 Å. Sn(1) is bonded to one Se(2), two equivalent Se(1), and two equivalent Se(3) atoms to form edge-sharing SnSe5 trigonal bipyramids. The Sn(1)-Se(2) bond length is 2.63 Å. There is one shorter (2.57 Å) and one longer (2.84 Å) Sn(1)-Se(1) bond length. There is one shorter (2.59 Å) and one longer (2.73 Å) Sn(1)-Se(3) bond length. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to two equivalent Cs(1) and two equivalent Sn(1) atoms. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to three equivalent Cs(1), one Sn(1), and one Se(2) atom. The Se(2)-Se(2) bond length is 2.44 Å. In the third Se site, Se(3) is bonded in a 4-coordinate geometry to two equivalent Cs(1) and two equivalent Sn(1) atoms.