Cs2(PSe2)3 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to one Se(3), one Se(5), two equivalent Se(1), two equivalent Se(2), two equivalent Se(4), and two equivalent Se(6) atoms. In the second Cs site, Cs(2) is bonded in a 8-coordinate geometry to one P(1), one Se(4), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(6) atoms. There are three inequivalent P sites. In the first P site, P(1) is bonded in a distorted rectangular see-saw-like geometry to one Cs(2), one P(1), one Se(3), and one Se(5) atom. In the second P site, P(2) is bonded in a 4-coordinate geometry to one P(3), one Se(1), one Se(4), and one Se(5) atom. In the third P site, P(3) is bonded in a distorted tetrahedral geometry to one P(2), one Se(2), one Se(3), and one Se(6) atom. There are six inequivalent Se sites. In the first Se site, Se(4) is bonded in a distorted single-bond geometry to one Cs(2), two equivalent Cs(1), and one P(2) atom. In the second Se site, Se(5) is bonded in an L-shaped geometry to one Cs(1), one P(1), and one P(2) atom. In the third Se site, Se(6) is bonded in a 5-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), and one P(3) atom. In the fourth Se site, Se(1) is bonded in a distorted single-bond geometry to two equivalent Cs(1), two equivalent Cs(2), and one P(2) atom. In the fifth Se site, Se(2) is bonded in a distorted single-bond geometry to two equivalent Cs(1), two equivalent Cs(2), and one P(3) atom. In the sixth Se site, Se(3) is bonded in a distorted water-like geometry to one Cs(1), one P(1), and one P(3) atom.
Cs2(PSe2)3 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to one Se(3), one Se(5), two equivalent Se(1), two equivalent Se(2), two equivalent Se(4), and two equivalent Se(6) atoms. The Cs(1)-Se(3) bond length is 3.96 Å. The Cs(1)-Se(5) bond length is 4.19 Å. There is one shorter (3.83 Å) and one longer (4.06 Å) Cs(1)-Se(1) bond length. There is one shorter (3.86 Å) and one longer (3.88 Å) Cs(1)-Se(2) bond length. There is one shorter (3.77 Å) and one longer (3.83 Å) Cs(1)-Se(4) bond length. There is one shorter (3.91 Å) and one longer (3.99 Å) Cs(1)-Se(6) bond length. In the second Cs site, Cs(2) is bonded in a 8-coordinate geometry to one P(1), one Se(4), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(6) atoms. The Cs(2)-P(1) bond length is 3.61 Å. The Cs(2)-Se(4) bond length is 3.93 Å. There is one shorter (3.77 Å) and one longer (4.07 Å) Cs(2)-Se(1) bond length. There is one shorter (3.82 Å) and one longer (3.84 Å) Cs(2)-Se(2) bond length. There is one shorter (3.70 Å) and one longer (3.74 Å) Cs(2)-Se(6) bond length. There are three inequivalent P sites. In the first P site, P(1) is bonded in a distorted rectangular see-saw-like geometry to one Cs(2), one P(1), one Se(3), and one Se(5) atom. The P(1)-P(1) bond length is 2.22 Å. The P(1)-Se(3) bond length is 2.31 Å. The P(1)-Se(5) bond length is 2.29 Å. In the second P site, P(2) is bonded in a 4-coordinate geometry to one P(3), one Se(1), one Se(4), and one Se(5) atom. The P(2)-P(3) bond length is 2.29 Å. The P(2)-Se(1) bond length is 2.13 Å. The P(2)-Se(4) bond length is 2.13 Å. The P(2)-Se(5) bond length is 2.30 Å. In the third P site, P(3) is bonded in a distorted tetrahedral geometry to one P(2), one Se(2), one Se(3), and one Se(6) atom. The P(3)-Se(2) bond length is 2.14 Å. The P(3)-Se(3) bond length is 2.33 Å. The P(3)-Se(6) bond length is 2.14 Å. There are six inequivalent Se sites. In the first Se site, Se(4) is bonded in a distorted single-bond geometry to one Cs(2), two equivalent Cs(1), and one P(2) atom. In the second Se site, Se(5) is bonded in an L-shaped geometry to one Cs(1), one P(1), and one P(2) atom. In the third Se site, Se(6) is bonded in a 5-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), and one P(3) atom. In the fourth Se site, Se(1) is bonded in a distorted single-bond geometry to two equivalent Cs(1), two equivalent Cs(2), and one P(2) atom. In the fifth Se site, Se(2) is bonded in a distorted single-bond geometry to two equivalent Cs(1), two equivalent Cs(2), and one P(3) atom. In the sixth Se site, Se(3) is bonded in a distorted water-like geometry to one Cs(1), one P(1), and one P(3) atom.