Tb7RhI12 is trigonal omega-derived structured and crystallizes in the trigonal R-3 space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to six equivalent I(1) atoms to form edge-sharing TbI6 octahedra. In the second Tb site, Tb(2) is bonded to one Rh(1), two equivalent I(1), and three equivalent I(2) atoms to form distorted TbRhI5 octahedra that share corners with three equivalent Tb(2)RhI5 octahedra,  an edgeedge with one Tb(1)I6 octahedra, and edges with five equivalent Tb(2)RhI5 octahedra. The corner-sharing octahedral tilt angles range from 0-9°. Rh(1) is bonded in an octahedral geometry to six equivalent Tb(2) atoms. There are two inequivalent I sites. In the first I site, I(1) is bonded in a distorted T-shaped geometry to one Tb(1) and two equivalent Tb(2) atoms. In the second I site, I(2) is bonded in a distorted T-shaped geometry to three equivalent Tb(2) atoms.
Tb7RhI12 is trigonal omega-derived structured and crystallizes in the trigonal R-3 space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to six equivalent I(1) atoms to form edge-sharing TbI6 octahedra. All Tb(1)-I(1) bond lengths are 3.04 Å. In the second Tb site, Tb(2) is bonded to one Rh(1), two equivalent I(1), and three equivalent I(2) atoms to form distorted TbRhI5 octahedra that share corners with three equivalent Tb(2)RhI5 octahedra,  an edgeedge with one Tb(1)I6 octahedra, and edges with five equivalent Tb(2)RhI5 octahedra. The corner-sharing octahedral tilt angles range from 0-9°. The Tb(2)-Rh(1) bond length is 2.69 Å. There is one shorter (3.21 Å) and one longer (3.23 Å) Tb(2)-I(1) bond length. There are a spread of Tb(2)-I(2) bond distances ranging from 3.12-3.37 Å. Rh(1) is bonded in an octahedral geometry to six equivalent Tb(2) atoms. There are two inequivalent I sites. In the first I site, I(1) is bonded in a distorted T-shaped geometry to one Tb(1) and two equivalent Tb(2) atoms. In the second I site, I(2) is bonded in a distorted T-shaped geometry to three equivalent Tb(2) atoms.