Rb5Tm3Br12 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 Br(3) atoms. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one Br(2), two equivalent Br(1), and four equivalent Br(3) atoms. Tm(1) is bonded to two equivalent Br(1), two equivalent Br(2), and two equivalent Br(3) atoms to form edge-sharing TmBr6 octahedra. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded to two equivalent Rb(2) and two equivalent Tm(1) atoms to form distorted corner-sharing BrRb2Tm2 trigonal pyramids. In the second Br site, Br(2) is bonded in a 3-coordinate geometry to one Rb(2) and two equivalent Tm(1) atoms. In the third Br site, Br(3) is bonded in a 5-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), and one Tm(1) atom.
Rb5Tm3Br12 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 Br(3) atoms. All Rb(1)-Br(3) bond lengths are 3.54 Å. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to one Br(2), two equivalent Br(1), and four equivalent Br(3) atoms. The Rb(2)-Br(2) bond length is 3.69 Å. Both Rb(2)-Br(1) bond lengths are 3.52 Å. All Rb(2)-Br(3) bond lengths are 3.48 Å. Tm(1) is bonded to two equivalent Br(1), two equivalent Br(2), and two equivalent Br(3) atoms to form edge-sharing TmBr6 octahedra. Both Tm(1)-Br(1) bond lengths are 2.90 Å. Both Tm(1)-Br(2) bond lengths are 2.88 Å. Both Tm(1)-Br(3) bond lengths are 2.80 Å. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded to two equivalent Rb(2) and two equivalent Tm(1) atoms to form distorted corner-sharing BrRb2Tm2 trigonal pyramids. In the second Br site, Br(2) is bonded in a 3-coordinate geometry to one Rb(2) and two equivalent Tm(1) atoms. In the third Br site, Br(3) is bonded in a 5-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), and one Tm(1) atom.