Hg3TlSb2Br3 crystallizes in the orthorhombic Pbcm space group. There are three inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a 3-coordinate geometry to two equivalent Sb(1) and one Br(3) atom. In the second Hg site, Hg(2) is bonded to two equivalent Sb(1), one Br(1), and one Br(2) atom to form distorted HgSb2Br2 trigonal pyramids that share corners with two equivalent Sb(1)Hg3Sb tetrahedra. In the third Hg site, Hg(3) is bonded in a linear geometry to two equivalent Sb(1) atoms. Tl(1) is bonded in a distorted single-bond geometry to one Br(1) atom. Sb(1) is bonded to one Hg(1), one Hg(2), one Hg(3), and one Sb(1) atom to form SbHg3Sb tetrahedra that share corners with three equivalent Sb(1)Hg3Sb tetrahedra and  a cornercorner with one Hg(2)Sb2Br2 trigonal pyramid. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded in a water-like geometry to one Hg(2) and one Tl(1) atom. In the second Br site, Br(2) is bonded in a distorted single-bond geometry to one Hg(2) atom. In the third Br site, Br(3) is bonded in a single-bond geometry to one Hg(1) atom.
Hg3TlSb2Br3 crystallizes in the orthorhombic Pbcm space group. There are three inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a 3-coordinate geometry to two equivalent Sb(1) and one Br(3) atom. Both Hg(1)-Sb(1) bond lengths are 2.76 Å. The Hg(1)-Br(3) bond length is 2.92 Å. In the second Hg site, Hg(2) is bonded to two equivalent Sb(1), one Br(1), and one Br(2) atom to form distorted HgSb2Br2 trigonal pyramids that share corners with two equivalent Sb(1)Hg3Sb tetrahedra. Both Hg(2)-Sb(1) bond lengths are 2.76 Å. The Hg(2)-Br(1) bond length is 2.92 Å. The Hg(2)-Br(2) bond length is 2.93 Å. In the third Hg site, Hg(3) is bonded in a linear geometry to two equivalent Sb(1) atoms. Both Hg(3)-Sb(1) bond lengths are 2.75 Å. Tl(1) is bonded in a distorted single-bond geometry to one Br(1) atom. The Tl(1)-Br(1) bond length is 3.19 Å. Sb(1) is bonded to one Hg(1), one Hg(2), one Hg(3), and one Sb(1) atom to form SbHg3Sb tetrahedra that share corners with three equivalent Sb(1)Hg3Sb tetrahedra and  a cornercorner with one Hg(2)Sb2Br2 trigonal pyramid. The Sb(1)-Sb(1) bond length is 2.82 Å. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded in a water-like geometry to one Hg(2) and one Tl(1) atom. In the second Br site, Br(2) is bonded in a distorted single-bond geometry to one Hg(2) atom. In the third Br site, Br(3) is bonded in a single-bond geometry to one Hg(1) atom.