Tl2PSe3 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 2-coordinate geometry to one Se(4) and one Se(6) atom. In the second Tl site, Tl(2) is bonded in a 4-coordinate geometry to one Se(1), one Se(4), and two equivalent Se(5) atoms. In the third Tl site, Tl(3) is bonded in a 2-coordinate geometry to one Se(3) and one Se(4) atom. In the fourth Tl site, Tl(4) is bonded in a 6-coordinate geometry to one Se(1), one Se(3), one Se(4), one Se(5), and two equivalent Se(6) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded in a distorted tetrahedral geometry to one P(1), one Se(1), one Se(3), and one Se(5) atom. In the second P site, P(2) is bonded in a distorted tetrahedral geometry to one P(2), one Se(2), one Se(4), and one Se(6) atom. There are six inequivalent Se sites. In the first Se site, Se(3) is bonded in a 3-coordinate geometry to one Tl(3), one Tl(4), and one P(1) atom. In the second Se site, Se(4) is bonded in a 1-coordinate geometry to one Tl(1), one Tl(2), one Tl(3), one Tl(4), and one P(2) atom. In the third Se site, Se(5) is bonded in a distorted single-bond geometry to one Tl(4), two equivalent Tl(2), and one P(1) atom. In the fourth Se site, Se(6) is bonded in a distorted L-shaped geometry to one Tl(1), two equivalent Tl(4), and one P(2) atom. In the fifth Se site, Se(1) is bonded in a distorted single-bond geometry to one Tl(2), one Tl(4), and one P(1) atom. In the sixth Se site, Se(2) is bonded in a single-bond geometry to one P(2) atom.
Tl2PSe3 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 2-coordinate geometry to one Se(4) and one Se(6) atom. The Tl(1)-Se(4) bond length is 3.25 Å. The Tl(1)-Se(6) bond length is 3.10 Å. In the second Tl site, Tl(2) is bonded in a 4-coordinate geometry to one Se(1), one Se(4), and two equivalent Se(5) atoms. The Tl(2)-Se(1) bond length is 3.29 Å. The Tl(2)-Se(4) bond length is 3.40 Å. There is one shorter (3.31 Å) and one longer (3.34 Å) Tl(2)-Se(5) bond length. In the third Tl site, Tl(3) is bonded in a 2-coordinate geometry to one Se(3) and one Se(4) atom. The Tl(3)-Se(3) bond length is 3.18 Å. The Tl(3)-Se(4) bond length is 3.25 Å. In the fourth Tl site, Tl(4) is bonded in a 6-coordinate geometry to one Se(1), one Se(3), one Se(4), one Se(5), and two equivalent Se(6) atoms. The Tl(4)-Se(1) bond length is 3.24 Å. The Tl(4)-Se(3) bond length is 3.19 Å. The Tl(4)-Se(4) bond length is 3.38 Å. The Tl(4)-Se(5) bond length is 3.33 Å. There is one shorter (3.41 Å) and one longer (3.45 Å) Tl(4)-Se(6) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded in a distorted tetrahedral geometry to one P(1), one Se(1), one Se(3), and one Se(5) atom. The P(1)-P(1) bond length is 2.28 Å. The P(1)-Se(1) bond length is 2.20 Å. The P(1)-Se(3) bond length is 2.18 Å. The P(1)-Se(5) bond length is 2.20 Å. In the second P site, P(2) is bonded in a distorted tetrahedral geometry to one P(2), one Se(2), one Se(4), and one Se(6) atom. The P(2)-P(2) bond length is 2.27 Å. The P(2)-Se(2) bond length is 2.17 Å. The P(2)-Se(4) bond length is 2.21 Å. The P(2)-Se(6) bond length is 2.19 Å. There are six inequivalent Se sites. In the first Se site, Se(3) is bonded in a 3-coordinate geometry to one Tl(3), one Tl(4), and one P(1) atom. In the second Se site, Se(4) is bonded in a 1-coordinate geometry to one Tl(1), one Tl(2), one Tl(3), one Tl(4), and one P(2) atom. In the third Se site, Se(5) is bonded in a distorted single-bond geometry to one Tl(4), two equivalent Tl(2), and one P(1) atom. In the fourth Se site, Se(6) is bonded in a distorted L-shaped geometry to one Tl(1), two equivalent Tl(4), and one P(2) atom. In the fifth Se site, Se(1) is bonded in a distorted single-bond geometry to one Tl(2), one Tl(4), and one P(1) atom. In the sixth Se site, Se(2) is bonded in a single-bond geometry to one P(2) atom.