HfTl2PbSe4 is Krennerite-derived structured and crystallizes in the monoclinic C2/c space group. Hf(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form HfSe6 octahedra that share edges with two equivalent Hf(1)Se6 octahedra and edges with four equivalent Pb(1)Se6 octahedra. Tl(1) is bonded in a 3-coordinate geometry to one Se(1) and two equivalent Se(2) atoms. Pb(1) is bonded to two equivalent Se(1) and four equivalent Se(2) atoms to form PbSe6 octahedra that share edges with two equivalent Pb(1)Se6 octahedra and edges with four equivalent Hf(1)Se6 octahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 2-coordinate geometry to two equivalent Hf(1), one Tl(1), and one Pb(1) atom. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Hf(1), two equivalent Tl(1), and two equivalent Pb(1) atoms.
HfTl2PbSe4 is Krennerite-derived structured and crystallizes in the monoclinic C2/c space group. Hf(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form HfSe6 octahedra that share edges with two equivalent Hf(1)Se6 octahedra and edges with four equivalent Pb(1)Se6 octahedra. Both Hf(1)-Se(2) bond lengths are 2.66 Å. There are two shorter (2.71 Å) and two longer (2.76 Å) Hf(1)-Se(1) bond lengths. Tl(1) is bonded in a 3-coordinate geometry to one Se(1) and two equivalent Se(2) atoms. The Tl(1)-Se(1) bond length is 3.25 Å. There is one shorter (3.20 Å) and one longer (3.24 Å) Tl(1)-Se(2) bond length. Pb(1) is bonded to two equivalent Se(1) and four equivalent Se(2) atoms to form PbSe6 octahedra that share edges with two equivalent Pb(1)Se6 octahedra and edges with four equivalent Hf(1)Se6 octahedra. Both Pb(1)-Se(1) bond lengths are 3.08 Å. There are two shorter (3.08 Å) and two longer (3.09 Å) Pb(1)-Se(2) bond lengths. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 2-coordinate geometry to two equivalent Hf(1), one Tl(1), and one Pb(1) atom. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Hf(1), two equivalent Tl(1), and two equivalent Pb(1) atoms.