Rb5(DyI4)3 crystallizes in the hexagonal P-62m space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to six equivalent I(3) atoms to form distorted RbI6 pentagonal pyramids that share corners with six equivalent Dy(1)I6 octahedra and faces with two equivalent Rb(1)I6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 69°. 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. Dy(1) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form DyI6 octahedra that share corners with four equivalent Rb(1)I6 pentagonal pyramids and edges with two equivalent Dy(1)I6 octahedra. There are three inequivalent I sites. In the first I site, I(1) is bonded to two equivalent Rb(2) and two equivalent Dy(1) atoms to form distorted corner-sharing IRb2Dy2 trigonal pyramids. In the second I site, I(2) is bonded in a 3-coordinate geometry to one Rb(2) and two equivalent Dy(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 Dy(1) atom.
Rb5(DyI4)3 crystallizes in the hexagonal P-62m space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to six equivalent I(3) atoms to form distorted RbI6 pentagonal pyramids that share corners with six equivalent Dy(1)I6 octahedra and faces with two equivalent Rb(1)I6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 69°. All Rb(1)-I(3) bond lengths are 3.76 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 3.79 Å. All Rb(2)-I(3) bond lengths are 3.68 Å. Dy(1) is bonded to two equivalent I(1), two equivalent I(2), and two equivalent I(3) atoms to form DyI6 octahedra that share corners with four equivalent Rb(1)I6 pentagonal pyramids and edges with two equivalent Dy(1)I6 octahedra. Both Dy(1)-I(1) bond lengths are 3.13 Å. Both Dy(1)-I(2) bond lengths are 3.10 Å. Both Dy(1)-I(3) bond lengths are 3.09 Å. There are three inequivalent I sites. In the first I site, I(1) is bonded to two equivalent Rb(2) and two equivalent Dy(1) atoms to form distorted corner-sharing IRb2Dy2 trigonal pyramids. In the second I site, I(2) is bonded in a 3-coordinate geometry to one Rb(2) and two equivalent Dy(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 Dy(1) atom.