Cs3Yb crystallizes in the hexagonal P6_3/mmc space group. Cs(1) is bonded to eight equivalent Cs(1) and four equivalent Yb(1) atoms to form distorted CsCs8Yb4 cuboctahedra that share corners with four equivalent Yb(1)Cs12 cuboctahedra, corners with fourteen equivalent Cs(1)Cs8Yb4 cuboctahedra, edges with six equivalent Yb(1)Cs12 cuboctahedra, edges with twelve equivalent Cs(1)Cs8Yb4 cuboctahedra, faces with four equivalent Yb(1)Cs12 cuboctahedra, and faces with sixteen equivalent Cs(1)Cs8Yb4 cuboctahedra. Yb(1) is bonded to twelve equivalent Cs(1) atoms to form distorted YbCs12 cuboctahedra that share corners with six equivalent Yb(1)Cs12 cuboctahedra, corners with twelve equivalent Cs(1)Cs8Yb4 cuboctahedra, edges with eighteen equivalent Cs(1)Cs8Yb4 cuboctahedra, faces with eight equivalent Yb(1)Cs12 cuboctahedra, and faces with twelve equivalent Cs(1)Cs8Yb4 cuboctahedra.
Cs3Yb crystallizes in the hexagonal P6_3/mmc space group. Cs(1) is bonded to eight equivalent Cs(1) and four equivalent Yb(1) atoms to form distorted CsCs8Yb4 cuboctahedra that share corners with four equivalent Yb(1)Cs12 cuboctahedra, corners with fourteen equivalent Cs(1)Cs8Yb4 cuboctahedra, edges with six equivalent Yb(1)Cs12 cuboctahedra, edges with twelve equivalent Cs(1)Cs8Yb4 cuboctahedra, faces with four equivalent Yb(1)Cs12 cuboctahedra, and faces with sixteen equivalent Cs(1)Cs8Yb4 cuboctahedra. There are a spread of Cs(1)-Cs(1) bond distances ranging from 4.85-5.28 Å. There are two shorter (4.94 Å) and two longer (5.07 Å) Cs(1)-Yb(1) bond lengths. Yb(1) is bonded to twelve equivalent Cs(1) atoms to form distorted YbCs12 cuboctahedra that share corners with six equivalent Yb(1)Cs12 cuboctahedra, corners with twelve equivalent Cs(1)Cs8Yb4 cuboctahedra, edges with eighteen equivalent Cs(1)Cs8Yb4 cuboctahedra, faces with eight equivalent Yb(1)Cs12 cuboctahedra, and faces with twelve equivalent Cs(1)Cs8Yb4 cuboctahedra.