Tb5Ir3 crystallizes in the tetragonal P4/ncc space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to two equivalent Ir(2) and three equivalent Ir(1) atoms to form distorted TbIr5 trigonal bipyramids that share corners with four equivalent Tb(2)Ir4 tetrahedra, corners with eleven equivalent Tb(1)Ir5 trigonal bipyramids,  an edgeedge with one Tb(2)Ir4 tetrahedra, edges with six equivalent Tb(1)Ir5 trigonal bipyramids, and faces with two equivalent Tb(1)Ir5 trigonal bipyramids. In the second Tb site, Tb(2) is bonded to four equivalent Ir(1) atoms to form TbIr4 tetrahedra that share corners with sixteen equivalent Tb(1)Ir5 trigonal bipyramids, edges with two equivalent Tb(2)Ir4 tetrahedra, and edges with four equivalent Tb(1)Ir5 trigonal bipyramids. There are two inequivalent Ir sites. In the first Ir site, Ir(1) is bonded in a 8-coordinate geometry to two equivalent Tb(2) and six equivalent Tb(1) atoms. In the second Ir site, Ir(2) is bonded in a 8-coordinate geometry to eight equivalent Tb(1) atoms.
Tb5Ir3 crystallizes in the tetragonal P4/ncc space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to two equivalent Ir(2) and three equivalent Ir(1) atoms to form distorted TbIr5 trigonal bipyramids that share corners with four equivalent Tb(2)Ir4 tetrahedra, corners with eleven equivalent Tb(1)Ir5 trigonal bipyramids,  an edgeedge with one Tb(2)Ir4 tetrahedra, edges with six equivalent Tb(1)Ir5 trigonal bipyramids, and faces with two equivalent Tb(1)Ir5 trigonal bipyramids. There is one shorter (2.91 Å) and one longer (2.95 Å) Tb(1)-Ir(2) bond length. There are a spread of Tb(1)-Ir(1) bond distances ranging from 2.87-3.15 Å. In the second Tb site, Tb(2) is bonded to four equivalent Ir(1) atoms to form TbIr4 tetrahedra that share corners with sixteen equivalent Tb(1)Ir5 trigonal bipyramids, edges with two equivalent Tb(2)Ir4 tetrahedra, and edges with four equivalent Tb(1)Ir5 trigonal bipyramids. All Tb(2)-Ir(1) bond lengths are 2.85 Å. There are two inequivalent Ir sites. In the first Ir site, Ir(1) is bonded in a 8-coordinate geometry to two equivalent Tb(2) and six equivalent Tb(1) atoms. In the second Ir site, Ir(2) is bonded in a 8-coordinate geometry to eight equivalent Tb(1) atoms.