K3Hg crystallizes in the tetragonal I4/mmm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to four equivalent K(1), four equivalent K(2), and four equivalent Hg(1) atoms to form distorted KK8Hg4 cuboctahedra that share corners with twelve equivalent K(1)K8Hg4 cuboctahedra, edges with eight equivalent K(1)K8Hg4 cuboctahedra, edges with eight equivalent K(2)K8Hg4 cuboctahedra, edges with eight equivalent Hg(1)K12 cuboctahedra, faces with four equivalent K(2)K8Hg4 cuboctahedra, faces with four equivalent Hg(1)K12 cuboctahedra, and faces with ten equivalent K(1)K8Hg4 cuboctahedra. In the second K site, K(2) is bonded to eight equivalent K(1) and four equivalent Hg(1) atoms to form distorted KK8Hg4 cuboctahedra that share corners with four equivalent K(2)K8Hg4 cuboctahedra, corners with eight equivalent Hg(1)K12 cuboctahedra, edges with eight equivalent K(2)K8Hg4 cuboctahedra, edges with sixteen equivalent K(1)K8Hg4 cuboctahedra, faces with four equivalent K(2)K8Hg4 cuboctahedra, faces with six equivalent Hg(1)K12 cuboctahedra, and faces with eight equivalent K(1)K8Hg4 cuboctahedra. Hg(1) is bonded to four equivalent K(2) and eight equivalent K(1) atoms to form distorted HgK12 cuboctahedra that share corners with four equivalent Hg(1)K12 cuboctahedra, corners with eight equivalent K(2)K8Hg4 cuboctahedra, edges with eight equivalent Hg(1)K12 cuboctahedra, edges with sixteen equivalent K(1)K8Hg4 cuboctahedra, faces with four equivalent Hg(1)K12 cuboctahedra, faces with six equivalent K(2)K8Hg4 cuboctahedra, and faces with eight equivalent K(1)K8Hg4 cuboctahedra.
K3Hg crystallizes in the tetragonal I4/mmm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to four equivalent K(1), four equivalent K(2), and four equivalent Hg(1) atoms to form distorted KK8Hg4 cuboctahedra that share corners with twelve equivalent K(1)K8Hg4 cuboctahedra, edges with eight equivalent K(1)K8Hg4 cuboctahedra, edges with eight equivalent K(2)K8Hg4 cuboctahedra, edges with eight equivalent Hg(1)K12 cuboctahedra, faces with four equivalent K(2)K8Hg4 cuboctahedra, faces with four equivalent Hg(1)K12 cuboctahedra, and faces with ten equivalent K(1)K8Hg4 cuboctahedra. All K(1)-K(1) bond lengths are 4.11 Å. All K(1)-K(2) bond lengths are 4.07 Å. All K(1)-Hg(1) bond lengths are 4.07 Å. In the second K site, K(2) is bonded to eight equivalent K(1) and four equivalent Hg(1) atoms to form distorted KK8Hg4 cuboctahedra that share corners with four equivalent K(2)K8Hg4 cuboctahedra, corners with eight equivalent Hg(1)K12 cuboctahedra, edges with eight equivalent K(2)K8Hg4 cuboctahedra, edges with sixteen equivalent K(1)K8Hg4 cuboctahedra, faces with four equivalent K(2)K8Hg4 cuboctahedra, faces with six equivalent Hg(1)K12 cuboctahedra, and faces with eight equivalent K(1)K8Hg4 cuboctahedra. All K(2)-Hg(1) bond lengths are 4.11 Å. Hg(1) is bonded to four equivalent K(2) and eight equivalent K(1) atoms to form distorted HgK12 cuboctahedra that share corners with four equivalent Hg(1)K12 cuboctahedra, corners with eight equivalent K(2)K8Hg4 cuboctahedra, edges with eight equivalent Hg(1)K12 cuboctahedra, edges with sixteen equivalent K(1)K8Hg4 cuboctahedra, faces with four equivalent Hg(1)K12 cuboctahedra, faces with six equivalent K(2)K8Hg4 cuboctahedra, and faces with eight equivalent K(1)K8Hg4 cuboctahedra.