Rb5(TmI4)3 crystallizes in the hexagonal P-62m space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 6-coordinate geometry to six equivalent I(3) atoms. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one I(2), two equivalent I(1), and four equivalent I(3) atoms. Tm(1) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form edge-sharing TmI6 octahedra. There are three inequivalent I sites. In the first I site, I(1) is bonded to two equivalent Rb(2) and two equivalent Tm(1) atoms to form distorted corner-sharing IRb2Tm2 trigonal pyramids. In the second I site, I(2) is bonded in a 3-coordinate geometry to one Rb(2) and two equivalent Tm(1) atoms. In the third I site, I(3) is bonded in a 5-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), and one Tm(1) atom.
Rb5(TmI4)3 crystallizes in the hexagonal P-62m space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 6-coordinate geometry to six equivalent I(3) atoms. All Rb(1)-I(3) bond lengths are 3.74 Å. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one I(2), two equivalent I(1), and four equivalent I(3) atoms. The Rb(2)-I(2) bond length is 3.93 Å. Both Rb(2)-I(1) bond lengths are 3.75 Å. All Rb(2)-I(3) bond lengths are 3.65 Å. Tm(1) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form edge-sharing TmI6 octahedra. Both Tm(1)-I(1) bond lengths are 3.09 Å. Both Tm(1)-I(2) bond lengths are 3.07 Å. Both Tm(1)-I(3) bond lengths are 3.05 Å. There are three inequivalent I sites. In the first I site, I(1) is bonded to two equivalent Rb(2) and two equivalent Tm(1) atoms to form distorted corner-sharing IRb2Tm2 trigonal pyramids. In the second I site, I(2) is bonded in a 3-coordinate geometry to one Rb(2) and two equivalent Tm(1) atoms. In the third I site, I(3) is bonded in a 5-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), and one Tm(1) atom.