ThTm3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. Th(1) is bonded to four equivalent Tm(2) and eight equivalent Tm(1) atoms to form ThTm12 cuboctahedra that share corners with four equivalent Th(1)Tm12 cuboctahedra, corners with eight equivalent Tm(2)Tm8Th4 cuboctahedra, edges with eight equivalent Th(1)Tm12 cuboctahedra, edges with sixteen equivalent Tm(1)Tm8Th4 cuboctahedra, faces with four equivalent Th(1)Tm12 cuboctahedra, faces with six equivalent Tm(2)Tm8Th4 cuboctahedra, and faces with eight equivalent Tm(1)Tm8Th4 cuboctahedra. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded to four equivalent Th(1), four equivalent Tm(1), and four equivalent Tm(2) atoms to form TmTm8Th4 cuboctahedra that share corners with twelve equivalent Tm(1)Tm8Th4 cuboctahedra, edges with eight equivalent Th(1)Tm12 cuboctahedra, edges with eight equivalent Tm(1)Tm8Th4 cuboctahedra, edges with eight equivalent Tm(2)Tm8Th4 cuboctahedra, faces with four equivalent Th(1)Tm12 cuboctahedra, faces with four equivalent Tm(2)Tm8Th4 cuboctahedra, and faces with ten equivalent Tm(1)Tm8Th4 cuboctahedra. In the second Tm site, Tm(2) is bonded to four equivalent Th(1) and eight equivalent Tm(1) atoms to form TmTm8Th4 cuboctahedra that share corners with four equivalent Tm(2)Tm8Th4 cuboctahedra, corners with eight equivalent Th(1)Tm12 cuboctahedra, edges with eight equivalent Tm(2)Tm8Th4 cuboctahedra, edges with sixteen equivalent Tm(1)Tm8Th4 cuboctahedra, faces with four equivalent Tm(2)Tm8Th4 cuboctahedra, faces with six equivalent Th(1)Tm12 cuboctahedra, and faces with eight equivalent Tm(1)Tm8Th4 cuboctahedra.
ThTm3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. Th(1) is bonded to four equivalent Tm(2) and eight equivalent Tm(1) atoms to form ThTm12 cuboctahedra that share corners with four equivalent Th(1)Tm12 cuboctahedra, corners with eight equivalent Tm(2)Tm8Th4 cuboctahedra, edges with eight equivalent Th(1)Tm12 cuboctahedra, edges with sixteen equivalent Tm(1)Tm8Th4 cuboctahedra, faces with four equivalent Th(1)Tm12 cuboctahedra, faces with six equivalent Tm(2)Tm8Th4 cuboctahedra, and faces with eight equivalent Tm(1)Tm8Th4 cuboctahedra. All Th(1)-Tm(2) bond lengths are 3.56 Å. All Th(1)-Tm(1) bond lengths are 3.50 Å. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded to four equivalent Th(1), four equivalent Tm(1), and four equivalent Tm(2) atoms to form TmTm8Th4 cuboctahedra that share corners with twelve equivalent Tm(1)Tm8Th4 cuboctahedra, edges with eight equivalent Th(1)Tm12 cuboctahedra, edges with eight equivalent Tm(1)Tm8Th4 cuboctahedra, edges with eight equivalent Tm(2)Tm8Th4 cuboctahedra, faces with four equivalent Th(1)Tm12 cuboctahedra, faces with four equivalent Tm(2)Tm8Th4 cuboctahedra, and faces with ten equivalent Tm(1)Tm8Th4 cuboctahedra. All Tm(1)-Tm(1) bond lengths are 3.56 Å. All Tm(1)-Tm(2) bond lengths are 3.50 Å. In the second Tm site, Tm(2) is bonded to four equivalent Th(1) and eight equivalent Tm(1) atoms to form TmTm8Th4 cuboctahedra that share corners with four equivalent Tm(2)Tm8Th4 cuboctahedra, corners with eight equivalent Th(1)Tm12 cuboctahedra, edges with eight equivalent Tm(2)Tm8Th4 cuboctahedra, edges with sixteen equivalent Tm(1)Tm8Th4 cuboctahedra, faces with four equivalent Tm(2)Tm8Th4 cuboctahedra, faces with six equivalent Th(1)Tm12 cuboctahedra, and faces with eight equivalent Tm(1)Tm8Th4 cuboctahedra.