Rb2UI5 crystallizes in the orthorhombic Pnma space group. Rb(1) is bonded in a 8-coordinate geometry to two equivalent I(1), two equivalent I(2), two equivalent I(3), and two equivalent I(4) atoms. U(1) is bonded to one I(1), one I(2), one I(3), and four equivalent I(4) atoms to form distorted edge-sharing UI7 pentagonal bipyramids. There are four inequivalent I sites. In the first I site, I(1) is bonded to four equivalent Rb(1) and one U(1) atom to form distorted IRb4U trigonal bipyramids that share corners with four equivalent I(4)Rb2U2 tetrahedra, corners with four equivalent I(1)Rb4U trigonal bipyramids, corners with four equivalent I(3)Rb4U trigonal bipyramids, edges with four equivalent I(4)Rb2U2 tetrahedra,  an edgeedge with one I(3)Rb4U trigonal bipyramid, and  a faceface with one I(3)Rb4U trigonal bipyramid. In the second I site, I(2) is bonded in a 5-coordinate geometry to four equivalent Rb(1) and one U(1) atom. In the third I site, I(3) is bonded to four equivalent Rb(1) and one U(1) atom to form distorted IRb4U trigonal bipyramids that share corners with eight equivalent I(4)Rb2U2 tetrahedra, corners with four equivalent I(1)Rb4U trigonal bipyramids, edges with two equivalent I(4)Rb2U2 tetrahedra,  an edgeedge with one I(1)Rb4U trigonal bipyramid, edges with two equivalent I(3)Rb4U trigonal bipyramids, and  a faceface with one I(1)Rb4U trigonal bipyramid. In the fourth I site, I(4) is bonded to two equivalent Rb(1) and two equivalent U(1) atoms to form distorted IRb2U2 tetrahedra that share corners with six equivalent I(4)Rb2U2 tetrahedra, corners with two equivalent I(1)Rb4U trigonal bipyramids, corners with four equivalent I(3)Rb4U trigonal bipyramids,  an edgeedge with one I(4)Rb2U2 tetrahedra,  an edgeedge with one I(3)Rb4U trigonal bipyramid, and edges with two equivalent I(1)Rb4U trigonal bipyramids.
Rb2UI5 crystallizes in the orthorhombic Pnma space group. Rb(1) is bonded in a 8-coordinate geometry to two equivalent I(1), two equivalent I(2), two equivalent I(3), and two equivalent I(4) atoms. There is one shorter (3.72 Å) and one longer (3.73 Å) Rb(1)-I(1) bond length. There is one shorter (3.84 Å) and one longer (3.98 Å) Rb(1)-I(2) bond length. There is one shorter (3.72 Å) and one longer (3.81 Å) Rb(1)-I(3) bond length. There is one shorter (3.89 Å) and one longer (3.94 Å) Rb(1)-I(4) bond length. U(1) is bonded to one I(1), one I(2), one I(3), and four equivalent I(4) atoms to form distorted edge-sharing UI7 pentagonal bipyramids. The U(1)-I(1) bond length is 3.19 Å. The U(1)-I(2) bond length is 3.20 Å. The U(1)-I(3) bond length is 3.23 Å. There are two shorter (3.24 Å) and two longer (3.25 Å) U(1)-I(4) bond lengths. There are four inequivalent I sites. In the first I site, I(1) is bonded to four equivalent Rb(1) and one U(1) atom to form distorted IRb4U trigonal bipyramids that share corners with four equivalent I(4)Rb2U2 tetrahedra, corners with four equivalent I(1)Rb4U trigonal bipyramids, corners with four equivalent I(3)Rb4U trigonal bipyramids, edges with four equivalent I(4)Rb2U2 tetrahedra,  an edgeedge with one I(3)Rb4U trigonal bipyramid, and  a faceface with one I(3)Rb4U trigonal bipyramid. In the second I site, I(2) is bonded in a 5-coordinate geometry to four equivalent Rb(1) and one U(1) atom. In the third I site, I(3) is bonded to four equivalent Rb(1) and one U(1) atom to form distorted IRb4U trigonal bipyramids that share corners with eight equivalent I(4)Rb2U2 tetrahedra, corners with four equivalent I(1)Rb4U trigonal bipyramids, edges with two equivalent I(4)Rb2U2 tetrahedra,  an edgeedge with one I(1)Rb4U trigonal bipyramid, edges with two equivalent I(3)Rb4U trigonal bipyramids, and  a faceface with one I(1)Rb4U trigonal bipyramid. In the fourth I site, I(4) is bonded to two equivalent Rb(1) and two equivalent U(1) atoms to form distorted IRb2U2 tetrahedra that share corners with six equivalent I(4)Rb2U2 tetrahedra, corners with two equivalent I(1)Rb4U trigonal bipyramids, corners with four equivalent I(3)Rb4U trigonal bipyramids,  an edgeedge with one I(4)Rb2U2 tetrahedra,  an edgeedge with one I(3)Rb4U trigonal bipyramid, and edges with two equivalent I(1)Rb4U trigonal bipyramids.