Cs2PSe5 crystallizes in the triclinic P-1 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 9-coordinate geometry to one Se(2), one Se(5), two equivalent Se(1), two equivalent Se(4), and three equivalent Se(3) atoms. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to one Se(3), two equivalent Se(1), two equivalent Se(2), and four equivalent Se(5) atoms. P(1) is bonded in a tetrahedral geometry to one Se(1), one Se(2), one Se(3), and one Se(5) atom. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to two equivalent Cs(1), two equivalent Cs(2), and one P(1) atom. In the second Se site, Se(2) is bonded in a 1-coordinate geometry to one Cs(1), two equivalent Cs(2), one P(1), and one Se(4) atom. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to one Cs(2), three equivalent Cs(1), and one P(1) atom. In the fourth Se site, Se(4) is bonded in a 4-coordinate geometry to two equivalent Cs(1), one Se(2), and one Se(4) atom. In the fifth Se site, Se(5) is bonded in a 6-coordinate geometry to one Cs(1), four equivalent Cs(2), and one P(1) atom.
Cs2PSe5 crystallizes in the triclinic P-1 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 9-coordinate geometry to one Se(2), one Se(5), two equivalent Se(1), two equivalent Se(4), and three equivalent Se(3) atoms. The Cs(1)-Se(2) bond length is 4.20 Å. The Cs(1)-Se(5) bond length is 3.98 Å. There is one shorter (3.84 Å) and one longer (3.95 Å) Cs(1)-Se(1) bond length. There is one shorter (3.80 Å) and one longer (3.84 Å) Cs(1)-Se(4) bond length. There are a spread of Cs(1)-Se(3) bond distances ranging from 3.73-3.88 Å. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to one Se(3), two equivalent Se(1), two equivalent Se(2), and four equivalent Se(5) atoms. The Cs(2)-Se(3) bond length is 3.66 Å. There is one shorter (3.77 Å) and one longer (4.11 Å) Cs(2)-Se(1) bond length. There is one shorter (3.79 Å) and one longer (3.84 Å) Cs(2)-Se(2) bond length. There are a spread of Cs(2)-Se(5) bond distances ranging from 3.74-3.85 Å. P(1) is bonded in a tetrahedral geometry to one Se(1), one Se(2), one Se(3), and one Se(5) atom. The P(1)-Se(1) bond length is 2.16 Å. The P(1)-Se(2) bond length is 2.34 Å. The P(1)-Se(3) bond length is 2.16 Å. The P(1)-Se(5) bond length is 2.19 Å. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to two equivalent Cs(1), two equivalent Cs(2), and one P(1) atom. In the second Se site, Se(2) is bonded in a 1-coordinate geometry to one Cs(1), two equivalent Cs(2), one P(1), and one Se(4) atom. The Se(2)-Se(4) bond length is 2.32 Å. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to one Cs(2), three equivalent Cs(1), and one P(1) atom. In the fourth Se site, Se(4) is bonded in a 4-coordinate geometry to two equivalent Cs(1), one Se(2), and one Se(4) atom. The Se(4)-Se(4) bond length is 2.44 Å. In the fifth Se site, Se(5) is bonded in a 6-coordinate geometry to one Cs(1), four equivalent Cs(2), and one P(1) atom.