Tl2Pt5S6 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Pt sites. In the first Pt site, Pt(1) is bonded in a 5-coordinate geometry to one Tl(1), two equivalent S(2), and two equivalent S(3) atoms. In the second Pt site, Pt(2) is bonded to two equivalent Tl(1), one S(2), one S(3), and two equivalent S(1) atoms to form distorted PtTl2S4 octahedra that share corners with two equivalent S(3)TlPt3 tetrahedra and edges with two equivalent Pt(2)Tl2S4 octahedra. In the third Pt site, Pt(3) is bonded in a 4-coordinate geometry to two equivalent Tl(1), two equivalent S(1), and two equivalent S(2) atoms. Tl(1) is bonded in a 5-coordinate geometry to one Pt(1), one Pt(3), two equivalent Pt(2), and one S(3) atom. There are three inequivalent S sites. In the first S site, S(1) is bonded in a distorted T-shaped geometry to one Pt(3) and two equivalent Pt(2) atoms. In the second S site, S(2) is bonded to one Pt(2), one Pt(3), and two equivalent Pt(1) atoms to form SPt4 tetrahedra that share corners with three equivalent S(2)Pt4 tetrahedra, corners with three equivalent S(3)TlPt3 tetrahedra, and  an edgeedge with one S(3)TlPt3 tetrahedra. In the third S site, S(3) is bonded to one Pt(2), two equivalent Pt(1), and one Tl(1) atom to form distorted STlPt3 tetrahedra that share corners with two equivalent Pt(2)Tl2S4 octahedra, corners with two equivalent S(3)TlPt3 tetrahedra, corners with three equivalent S(2)Pt4 tetrahedra, and  an edgeedge with one S(2)Pt4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-88°.
Tl2Pt5S6 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Pt sites. In the first Pt site, Pt(1) is bonded in a 5-coordinate geometry to one Tl(1), two equivalent S(2), and two equivalent S(3) atoms. The Pt(1)-Tl(1) bond length is 3.15 Å. There is one shorter (2.31 Å) and one longer (2.34 Å) Pt(1)-S(2) bond length. There is one shorter (2.33 Å) and one longer (2.37 Å) Pt(1)-S(3) bond length. In the second Pt site, Pt(2) is bonded to two equivalent Tl(1), one S(2), one S(3), and two equivalent S(1) atoms to form distorted PtTl2S4 octahedra that share corners with two equivalent S(3)TlPt3 tetrahedra and edges with two equivalent Pt(2)Tl2S4 octahedra. There is one shorter (3.12 Å) and one longer (3.17 Å) Pt(2)-Tl(1) bond length. The Pt(2)-S(2) bond length is 2.36 Å. The Pt(2)-S(3) bond length is 2.31 Å. There is one shorter (2.36 Å) and one longer (2.38 Å) Pt(2)-S(1) bond length. In the third Pt site, Pt(3) is bonded in a 4-coordinate geometry to two equivalent Tl(1), two equivalent S(1), and two equivalent S(2) atoms. Both Pt(3)-Tl(1) bond lengths are 3.35 Å. Both Pt(3)-S(1) bond lengths are 2.38 Å. Both Pt(3)-S(2) bond lengths are 2.32 Å. Tl(1) is bonded in a 5-coordinate geometry to one Pt(1), one Pt(3), two equivalent Pt(2), and one S(3) atom. The Tl(1)-S(3) bond length is 3.09 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded in a distorted T-shaped geometry to one Pt(3) and two equivalent Pt(2) atoms. In the second S site, S(2) is bonded to one Pt(2), one Pt(3), and two equivalent Pt(1) atoms to form SPt4 tetrahedra that share corners with three equivalent S(2)Pt4 tetrahedra, corners with three equivalent S(3)TlPt3 tetrahedra, and  an edgeedge with one S(3)TlPt3 tetrahedra. In the third S site, S(3) is bonded to one Pt(2), two equivalent Pt(1), and one Tl(1) atom to form distorted STlPt3 tetrahedra that share corners with two equivalent Pt(2)Tl2S4 octahedra, corners with two equivalent S(3)TlPt3 tetrahedra, corners with three equivalent S(2)Pt4 tetrahedra, and  an edgeedge with one S(2)Pt4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-88°.