AcEu3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Ac(1) is bonded to twelve equivalent Eu(1) atoms to form AcEu12 cuboctahedra that share corners with six equivalent Ac(1)Eu12 cuboctahedra, corners with twelve equivalent Eu(1)Ac4Eu8 cuboctahedra, edges with eighteen equivalent Eu(1)Ac4Eu8 cuboctahedra, faces with eight equivalent Ac(1)Eu12 cuboctahedra, and faces with twelve equivalent Eu(1)Ac4Eu8 cuboctahedra. Eu(1) is bonded to four equivalent Ac(1) and eight equivalent Eu(1) atoms to form EuAc4Eu8 cuboctahedra that share corners with four equivalent Ac(1)Eu12 cuboctahedra, corners with fourteen equivalent Eu(1)Ac4Eu8 cuboctahedra, edges with six equivalent Ac(1)Eu12 cuboctahedra, edges with twelve equivalent Eu(1)Ac4Eu8 cuboctahedra, faces with four equivalent Ac(1)Eu12 cuboctahedra, and faces with sixteen equivalent Eu(1)Ac4Eu8 cuboctahedra.
AcEu3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Ac(1) is bonded to twelve equivalent Eu(1) atoms to form AcEu12 cuboctahedra that share corners with six equivalent Ac(1)Eu12 cuboctahedra, corners with twelve equivalent Eu(1)Ac4Eu8 cuboctahedra, edges with eighteen equivalent Eu(1)Ac4Eu8 cuboctahedra, faces with eight equivalent Ac(1)Eu12 cuboctahedra, and faces with twelve equivalent Eu(1)Ac4Eu8 cuboctahedra. There are six shorter (3.96 Å) and six longer (4.00 Å) Ac(1)-Eu(1) bond lengths. Eu(1) is bonded to four equivalent Ac(1) and eight equivalent Eu(1) atoms to form EuAc4Eu8 cuboctahedra that share corners with four equivalent Ac(1)Eu12 cuboctahedra, corners with fourteen equivalent Eu(1)Ac4Eu8 cuboctahedra, edges with six equivalent Ac(1)Eu12 cuboctahedra, edges with twelve equivalent Eu(1)Ac4Eu8 cuboctahedra, faces with four equivalent Ac(1)Eu12 cuboctahedra, and faces with sixteen equivalent Eu(1)Ac4Eu8 cuboctahedra. There are a spread of Eu(1)-Eu(1) bond distances ranging from 3.97-4.02 Å.