RbNd2I5 crystallizes in the monoclinic P2_1/c space group. Rb(1) is bonded in a 9-coordinate geometry to two equivalent I(1), two equivalent I(3), two equivalent I(4), and three equivalent I(5) atoms. There are two inequivalent Nd sites. In the first Nd site, Nd(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. In the second Nd site, Nd(2) is bonded to one I(1), one I(3), one I(4), two equivalent I(2), and two equivalent I(5) atoms to form distorted edge-sharing NdI7 pentagonal bipyramids. There are five inequivalent I sites. In the first I site, I(1) is bonded in a 5-coordinate geometry to two equivalent Rb(1), one Nd(2), and two equivalent Nd(1) atoms. In the second I site, I(2) is bonded to two equivalent Nd(1) and two equivalent Nd(2) atoms to form distorted INd4 tetrahedra that share corners with four equivalent I(4)Rb2Nd3 square pyramids, corners with two equivalent I(2)Nd4 tetrahedra, corners with two equivalent I(3)Rb2Nd3 trigonal bipyramids,  an edgeedge with one I(4)Rb2Nd3 square pyramid,  an edgeedge with one I(2)Nd4 tetrahedra, and edges with two equivalent I(3)Rb2Nd3 trigonal bipyramids. In the third I site, I(3) is bonded to two equivalent Rb(1), one Nd(2), and two equivalent Nd(1) atoms to form distorted IRb2Nd3 trigonal bipyramids that share corners with four equivalent I(4)Rb2Nd3 square pyramids, corners with two equivalent I(2)Nd4 tetrahedra, corners with four equivalent I(3)Rb2Nd3 trigonal bipyramids,  an edgeedge with one I(4)Rb2Nd3 square pyramid, edges with two equivalent I(2)Nd4 tetrahedra, and  a faceface with one I(4)Rb2Nd3 square pyramid. In the fourth I site, I(4) is bonded to two equivalent Rb(1), one Nd(2), and two equivalent Nd(1) atoms to form distorted IRb2Nd3 square pyramids that share corners with four equivalent I(2)Nd4 tetrahedra, corners with four equivalent I(3)Rb2Nd3 trigonal bipyramids, edges with two equivalent I(4)Rb2Nd3 square pyramids,  an edgeedge with one I(2)Nd4 tetrahedra,  an edgeedge with one I(3)Rb2Nd3 trigonal bipyramid, and  a faceface with one I(3)Rb2Nd3 trigonal bipyramid. In the fifth I site, I(5) is bonded in a 4-coordinate geometry to three equivalent Rb(1) and two equivalent Nd(2) atoms.
RbNd2I5 crystallizes in the monoclinic P2_1/c space group. Rb(1) is bonded in a 9-coordinate geometry to two equivalent I(1), two equivalent I(3), two equivalent I(4), and three equivalent I(5) atoms. There is one shorter (3.82 Å) and one longer (4.03 Å) Rb(1)-I(1) bond length. There is one shorter (3.65 Å) and one longer (3.74 Å) Rb(1)-I(3) bond length. There is one shorter (3.76 Å) and one longer (3.83 Å) Rb(1)-I(4) bond length. There are a spread of Rb(1)-I(5) bond distances ranging from 3.69-4.27 Å. There are two inequivalent Nd sites. In the first Nd site, Nd(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 (3.34 Å) and one longer (3.45 Å) Nd(1)-I(1) bond length. There is one shorter (3.33 Å) and one longer (3.63 Å) Nd(1)-I(2) bond length. There is one shorter (3.25 Å) and one longer (3.45 Å) Nd(1)-I(3) bond length. There is one shorter (3.27 Å) and one longer (3.39 Å) Nd(1)-I(4) bond length. In the second Nd site, Nd(2) is bonded to one I(1), one I(3), one I(4), two equivalent I(2), and two equivalent I(5) atoms to form distorted edge-sharing NdI7 pentagonal bipyramids. The Nd(2)-I(1) bond length is 3.34 Å. The Nd(2)-I(3) bond length is 3.23 Å. The Nd(2)-I(4) bond length is 3.29 Å. There is one shorter (3.22 Å) and one longer (3.23 Å) Nd(2)-I(2) bond length. There is one shorter (3.29 Å) and one longer (3.43 Å) Nd(2)-I(5) bond length. There are five inequivalent I sites. In the first I site, I(1) is bonded in a 5-coordinate geometry to two equivalent Rb(1), one Nd(2), and two equivalent Nd(1) atoms. In the second I site, I(2) is bonded to two equivalent Nd(1) and two equivalent Nd(2) atoms to form distorted INd4 tetrahedra that share corners with four equivalent I(4)Rb2Nd3 square pyramids, corners with two equivalent I(2)Nd4 tetrahedra, corners with two equivalent I(3)Rb2Nd3 trigonal bipyramids,  an edgeedge with one I(4)Rb2Nd3 square pyramid,  an edgeedge with one I(2)Nd4 tetrahedra, and edges with two equivalent I(3)Rb2Nd3 trigonal bipyramids. In the third I site, I(3) is bonded to two equivalent Rb(1), one Nd(2), and two equivalent Nd(1) atoms to form distorted IRb2Nd3 trigonal bipyramids that share corners with four equivalent I(4)Rb2Nd3 square pyramids, corners with two equivalent I(2)Nd4 tetrahedra, corners with four equivalent I(3)Rb2Nd3 trigonal bipyramids,  an edgeedge with one I(4)Rb2Nd3 square pyramid, edges with two equivalent I(2)Nd4 tetrahedra, and  a faceface with one I(4)Rb2Nd3 square pyramid. In the fourth I site, I(4) is bonded to two equivalent Rb(1), one Nd(2), and two equivalent Nd(1) atoms to form distorted IRb2Nd3 square pyramids that share corners with four equivalent I(2)Nd4 tetrahedra, corners with four equivalent I(3)Rb2Nd3 trigonal bipyramids, edges with two equivalent I(4)Rb2Nd3 square pyramids,  an edgeedge with one I(2)Nd4 tetrahedra,  an edgeedge with one I(3)Rb2Nd3 trigonal bipyramid, and  a faceface with one I(3)Rb2Nd3 trigonal bipyramid. In the fifth I site, I(5) is bonded in a 4-coordinate geometry to three equivalent Rb(1) and two equivalent Nd(2) atoms.