Tm3Tl is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Tm(1) is bonded to eight equivalent Tm(1) and four equivalent Tl(1) atoms to form distorted TmTm8Tl4 cuboctahedra that share corners with four equivalent Tl(1)Tm12 cuboctahedra, corners with fourteen equivalent Tm(1)Tm8Tl4 cuboctahedra, edges with six equivalent Tl(1)Tm12 cuboctahedra, edges with twelve equivalent Tm(1)Tm8Tl4 cuboctahedra, faces with four equivalent Tl(1)Tm12 cuboctahedra, and faces with sixteen equivalent Tm(1)Tm8Tl4 cuboctahedra. Tl(1) is bonded to twelve equivalent Tm(1) atoms to form TlTm12 cuboctahedra that share corners with six equivalent Tl(1)Tm12 cuboctahedra, corners with twelve equivalent Tm(1)Tm8Tl4 cuboctahedra, edges with eighteen equivalent Tm(1)Tm8Tl4 cuboctahedra, faces with eight equivalent Tl(1)Tm12 cuboctahedra, and faces with twelve equivalent Tm(1)Tm8Tl4 cuboctahedra.
Tm3Tl is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Tm(1) is bonded to eight equivalent Tm(1) and four equivalent Tl(1) atoms to form distorted TmTm8Tl4 cuboctahedra that share corners with four equivalent Tl(1)Tm12 cuboctahedra, corners with fourteen equivalent Tm(1)Tm8Tl4 cuboctahedra, edges with six equivalent Tl(1)Tm12 cuboctahedra, edges with twelve equivalent Tm(1)Tm8Tl4 cuboctahedra, faces with four equivalent Tl(1)Tm12 cuboctahedra, and faces with sixteen equivalent Tm(1)Tm8Tl4 cuboctahedra. There are a spread of Tm(1)-Tm(1) bond distances ranging from 3.31-3.42 Å. All Tm(1)-Tl(1) bond lengths are 3.37 Å. Tl(1) is bonded to twelve equivalent Tm(1) atoms to form TlTm12 cuboctahedra that share corners with six equivalent Tl(1)Tm12 cuboctahedra, corners with twelve equivalent Tm(1)Tm8Tl4 cuboctahedra, edges with eighteen equivalent Tm(1)Tm8Tl4 cuboctahedra, faces with eight equivalent Tl(1)Tm12 cuboctahedra, and faces with twelve equivalent Tm(1)Tm8Tl4 cuboctahedra.