CsPSe6 crystallizes in the monoclinic Pc space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 14-coordinate geometry to one Se(1), one Se(2), one Se(5), one Se(6), two equivalent Se(10), two equivalent Se(9), three equivalent Se(11), and three equivalent Se(12) atoms. In the second Cs site, Cs(2) is bonded in a 16-coordinate geometry to two equivalent P(2), one Se(1), one Se(2), one Se(5), one Se(6), two equivalent Se(3), two equivalent Se(4), three equivalent Se(7), and three equivalent Se(8) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one Se(11), one Se(12), one Se(5), and one Se(6) atom. In the second P site, P(2) is bonded to two equivalent Cs(2), one Se(1), one Se(2), one Se(7), and one Se(8) atom to form PCs2Se4 tetrahedra that share  a cornercorner with one Se(10)Cs2Se2 tetrahedra,  a cornercorner with one Se(9)Cs2Se2 tetrahedra, and corners with two equivalent P(2)Cs2Se4 tetrahedra. There are twelve inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one P(2), and one Se(9) atom. In the second Se site, Se(2) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one P(2), and one Se(10) atom. In the third Se site, Se(3) is bonded in a 2-coordinate geometry to two equivalent Cs(2), one Se(10), and one Se(6) atom. In the fourth Se site, Se(4) is bonded in a 2-coordinate geometry to two equivalent Cs(2), one Se(5), and one Se(9) atom. In the fifth Se site, Se(5) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one P(1), and one Se(4) atom. In the sixth Se site, Se(6) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one P(1), and one Se(3) atom. In the seventh Se site, Se(7) is bonded in a distorted single-bond geometry to three equivalent Cs(2) and one P(2) atom. In the eighth Se site, Se(8) is bonded in a distorted single-bond geometry to three equivalent Cs(2) and one P(2) atom. In the ninth Se site, Se(9) is bonded to two equivalent Cs(1), one Se(1), and one Se(4) atom to form distorted SeCs2Se2 tetrahedra that share  a cornercorner with one P(2)Cs2Se4 tetrahedra, corners with two equivalent Se(10)Cs2Se2 tetrahedra, corners with two equivalent Se(9)Cs2Se2 tetrahedra, and  an edgeedge with one Se(10)Cs2Se2 tetrahedra. In the tenth Se site, Se(10) is bonded to two equivalent Cs(1), one Se(2), and one Se(3) atom to form distorted SeCs2Se2 tetrahedra that share  a cornercorner with one P(2)Cs2Se4 tetrahedra, corners with two equivalent Se(10)Cs2Se2 tetrahedra, corners with two equivalent Se(9)Cs2Se2 tetrahedra, and  an edgeedge with one Se(9)Cs2Se2 tetrahedra. In the eleventh Se site, Se(11) is bonded in a distorted single-bond geometry to three equivalent Cs(1) and one P(1) atom. In the twelfth Se site, Se(12) is bonded in a distorted single-bond geometry to three equivalent Cs(1) and one P(1) atom.
CsPSe6 crystallizes in the monoclinic Pc space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 14-coordinate geometry to one Se(1), one Se(2), one Se(5), one Se(6), two equivalent Se(10), two equivalent Se(9), three equivalent Se(11), and three equivalent Se(12) atoms. The Cs(1)-Se(1) bond length is 4.09 Å. The Cs(1)-Se(2) bond length is 4.10 Å. The Cs(1)-Se(5) bond length is 3.94 Å. The Cs(1)-Se(6) bond length is 3.95 Å. There is one shorter (4.07 Å) and one longer (4.12 Å) Cs(1)-Se(10) bond length. There is one shorter (4.07 Å) and one longer (4.11 Å) Cs(1)-Se(9) bond length. There are a spread of Cs(1)-Se(11) bond distances ranging from 3.92-4.15 Å. There are a spread of Cs(1)-Se(12) bond distances ranging from 3.92-4.16 Å. In the second Cs site, Cs(2) is bonded in a 16-coordinate geometry to two equivalent P(2), one Se(1), one Se(2), one Se(5), one Se(6), two equivalent Se(3), two equivalent Se(4), three equivalent Se(7), and three equivalent Se(8) atoms. There is one shorter (3.89 Å) and one longer (3.91 Å) Cs(2)-P(2) bond length. The Cs(2)-Se(1) bond length is 3.70 Å. The Cs(2)-Se(2) bond length is 3.71 Å. The Cs(2)-Se(5) bond length is 4.17 Å. The Cs(2)-Se(6) bond length is 4.12 Å. There is one shorter (4.22 Å) and one longer (4.38 Å) Cs(2)-Se(3) bond length. Both Cs(2)-Se(4) bond lengths are 4.28 Å. There are a spread of Cs(2)-Se(7) bond distances ranging from 3.78-4.38 Å. There are a spread of Cs(2)-Se(8) bond distances ranging from 3.79-4.30 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one Se(11), one Se(12), one Se(5), and one Se(6) atom. The P(1)-Se(11) bond length is 2.15 Å. The P(1)-Se(12) bond length is 2.15 Å. The P(1)-Se(5) bond length is 2.27 Å. The P(1)-Se(6) bond length is 2.27 Å. In the second P site, P(2) is bonded to two equivalent Cs(2), one Se(1), one Se(2), one Se(7), and one Se(8) atom to form PCs2Se4 tetrahedra that share  a cornercorner with one Se(10)Cs2Se2 tetrahedra,  a cornercorner with one Se(9)Cs2Se2 tetrahedra, and corners with two equivalent P(2)Cs2Se4 tetrahedra. The P(2)-Se(1) bond length is 2.29 Å. The P(2)-Se(2) bond length is 2.29 Å. The P(2)-Se(7) bond length is 2.15 Å. The P(2)-Se(8) bond length is 2.15 Å. There are twelve inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one P(2), and one Se(9) atom. The Se(1)-Se(9) bond length is 2.37 Å. In the second Se site, Se(2) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one P(2), and one Se(10) atom. The Se(2)-Se(10) bond length is 2.37 Å. In the third Se site, Se(3) is bonded in a 2-coordinate geometry to two equivalent Cs(2), one Se(10), and one Se(6) atom. The Se(3)-Se(10) bond length is 2.40 Å. The Se(3)-Se(6) bond length is 2.38 Å. In the fourth Se site, Se(4) is bonded in a 2-coordinate geometry to two equivalent Cs(2), one Se(5), and one Se(9) atom. The Se(4)-Se(5) bond length is 2.37 Å. The Se(4)-Se(9) bond length is 2.40 Å. In the fifth Se site, Se(5) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one P(1), and one Se(4) atom. In the sixth Se site, Se(6) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one P(1), and one Se(3) atom. In the seventh Se site, Se(7) is bonded in a distorted single-bond geometry to three equivalent Cs(2) and one P(2) atom. In the eighth Se site, Se(8) is bonded in a distorted single-bond geometry to three equivalent Cs(2) and one P(2) atom. In the ninth Se site, Se(9) is bonded to two equivalent Cs(1), one Se(1), and one Se(4) atom to form distorted SeCs2Se2 tetrahedra that share  a cornercorner with one P(2)Cs2Se4 tetrahedra, corners with two equivalent Se(10)Cs2Se2 tetrahedra, corners with two equivalent Se(9)Cs2Se2 tetrahedra, and  an edgeedge with one Se(10)Cs2Se2 tetrahedra. In the tenth Se site, Se(10) is bonded to two equivalent Cs(1), one Se(2), and one Se(3) atom to form distorted SeCs2Se2 tetrahedra that share  a cornercorner with one P(2)Cs2Se4 tetrahedra, corners with two equivalent Se(10)Cs2Se2 tetrahedra, corners with two equivalent Se(9)Cs2Se2 tetrahedra, and  an edgeedge with one Se(9)Cs2Se2 tetrahedra. In the eleventh Se site, Se(11) is bonded in a distorted single-bond geometry to three equivalent Cs(1) and one P(1) atom. In the twelfth Se site, Se(12) is bonded in a distorted single-bond geometry to three equivalent Cs(1) and one P(1) atom.