ThTb3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Th(1) is bonded to twelve equivalent Tb(1) atoms to form ThTb12 cuboctahedra that share corners with six equivalent Th(1)Tb12 cuboctahedra, corners with twelve equivalent Tb(1)Tb8Th4 cuboctahedra, edges with eighteen equivalent Tb(1)Tb8Th4 cuboctahedra, faces with eight equivalent Th(1)Tb12 cuboctahedra, and faces with twelve equivalent Tb(1)Tb8Th4 cuboctahedra. Tb(1) is bonded to four equivalent Th(1) and eight equivalent Tb(1) atoms to form TbTb8Th4 cuboctahedra that share corners with four equivalent Th(1)Tb12 cuboctahedra, corners with fourteen equivalent Tb(1)Tb8Th4 cuboctahedra, edges with six equivalent Th(1)Tb12 cuboctahedra, edges with twelve equivalent Tb(1)Tb8Th4 cuboctahedra, faces with four equivalent Th(1)Tb12 cuboctahedra, and faces with sixteen equivalent Tb(1)Tb8Th4 cuboctahedra.
ThTb3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Th(1) is bonded to twelve equivalent Tb(1) atoms to form ThTb12 cuboctahedra that share corners with six equivalent Th(1)Tb12 cuboctahedra, corners with twelve equivalent Tb(1)Tb8Th4 cuboctahedra, edges with eighteen equivalent Tb(1)Tb8Th4 cuboctahedra, faces with eight equivalent Th(1)Tb12 cuboctahedra, and faces with twelve equivalent Tb(1)Tb8Th4 cuboctahedra. There are six shorter (3.56 Å) and six longer (3.61 Å) Th(1)-Tb(1) bond lengths. Tb(1) is bonded to four equivalent Th(1) and eight equivalent Tb(1) atoms to form TbTb8Th4 cuboctahedra that share corners with four equivalent Th(1)Tb12 cuboctahedra, corners with fourteen equivalent Tb(1)Tb8Th4 cuboctahedra, edges with six equivalent Th(1)Tb12 cuboctahedra, edges with twelve equivalent Tb(1)Tb8Th4 cuboctahedra, faces with four equivalent Th(1)Tb12 cuboctahedra, and faces with sixteen equivalent Tb(1)Tb8Th4 cuboctahedra. There are a spread of Tb(1)-Tb(1) bond distances ranging from 3.57-3.64 Å.