RhHg3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Rh(1) is bonded to twelve equivalent Hg(1) atoms to form RhHg12 cuboctahedra that share corners with six equivalent Rh(1)Hg12 cuboctahedra, corners with twelve equivalent Hg(1)Hg8Rh4 cuboctahedra, edges with eighteen equivalent Hg(1)Hg8Rh4 cuboctahedra, faces with eight equivalent Rh(1)Hg12 cuboctahedra, and faces with twelve equivalent Hg(1)Hg8Rh4 cuboctahedra. Hg(1) is bonded to four equivalent Rh(1) and eight equivalent Hg(1) atoms to form distorted HgHg8Rh4 cuboctahedra that share corners with four equivalent Rh(1)Hg12 cuboctahedra, corners with fourteen equivalent Hg(1)Hg8Rh4 cuboctahedra, edges with six equivalent Rh(1)Hg12 cuboctahedra, edges with twelve equivalent Hg(1)Hg8Rh4 cuboctahedra, faces with four equivalent Rh(1)Hg12 cuboctahedra, and faces with sixteen equivalent Hg(1)Hg8Rh4 cuboctahedra.
RhHg3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Rh(1) is bonded to twelve equivalent Hg(1) atoms to form RhHg12 cuboctahedra that share corners with six equivalent Rh(1)Hg12 cuboctahedra, corners with twelve equivalent Hg(1)Hg8Rh4 cuboctahedra, edges with eighteen equivalent Hg(1)Hg8Rh4 cuboctahedra, faces with eight equivalent Rh(1)Hg12 cuboctahedra, and faces with twelve equivalent Hg(1)Hg8Rh4 cuboctahedra. There are six shorter (3.01 Å) and six longer (3.05 Å) Rh(1)-Hg(1) bond lengths. Hg(1) is bonded to four equivalent Rh(1) and eight equivalent Hg(1) atoms to form distorted HgHg8Rh4 cuboctahedra that share corners with four equivalent Rh(1)Hg12 cuboctahedra, corners with fourteen equivalent Hg(1)Hg8Rh4 cuboctahedra, edges with six equivalent Rh(1)Hg12 cuboctahedra, edges with twelve equivalent Hg(1)Hg8Rh4 cuboctahedra, faces with four equivalent Rh(1)Hg12 cuboctahedra, and faces with sixteen equivalent Hg(1)Hg8Rh4 cuboctahedra. There are a spread of Hg(1)-Hg(1) bond distances ranging from 2.93-3.10 Å.