HgGa3 crystallizes in the tetragonal I4/mmm space group. Hg(1) is bonded to four equivalent Ga(2) and eight equivalent Ga(1) atoms to form HgGa12 cuboctahedra that share corners with four equivalent Hg(1)Ga12 cuboctahedra, edges with eight equivalent Hg(1)Ga12 cuboctahedra, edges with sixteen equivalent Ga(1)Ga8Hg4 cuboctahedra, faces with four equivalent Hg(1)Ga12 cuboctahedra, and faces with eight equivalent Ga(1)Ga8Hg4 cuboctahedra. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to four equivalent Hg(1), four equivalent Ga(1), and four equivalent Ga(2) atoms to form distorted GaGa8Hg4 cuboctahedra that share corners with twelve equivalent Ga(1)Ga8Hg4 cuboctahedra, edges with eight equivalent Hg(1)Ga12 cuboctahedra, edges with eight equivalent Ga(1)Ga8Hg4 cuboctahedra, faces with four equivalent Hg(1)Ga12 cuboctahedra, and faces with ten equivalent Ga(1)Ga8Hg4 cuboctahedra. In the second Ga site, Ga(2) is bonded in a square co-planar geometry to four equivalent Hg(1) and eight equivalent Ga(1) atoms.
HgGa3 crystallizes in the tetragonal I4/mmm space group. Hg(1) is bonded to four equivalent Ga(2) and eight equivalent Ga(1) atoms to form HgGa12 cuboctahedra that share corners with four equivalent Hg(1)Ga12 cuboctahedra, edges with eight equivalent Hg(1)Ga12 cuboctahedra, edges with sixteen equivalent Ga(1)Ga8Hg4 cuboctahedra, faces with four equivalent Hg(1)Ga12 cuboctahedra, and faces with eight equivalent Ga(1)Ga8Hg4 cuboctahedra. All Hg(1)-Ga(2) bond lengths are 3.00 Å. All Hg(1)-Ga(1) bond lengths are 3.15 Å. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to four equivalent Hg(1), four equivalent Ga(1), and four equivalent Ga(2) atoms to form distorted GaGa8Hg4 cuboctahedra that share corners with twelve equivalent Ga(1)Ga8Hg4 cuboctahedra, edges with eight equivalent Hg(1)Ga12 cuboctahedra, edges with eight equivalent Ga(1)Ga8Hg4 cuboctahedra, faces with four equivalent Hg(1)Ga12 cuboctahedra, and faces with ten equivalent Ga(1)Ga8Hg4 cuboctahedra. All Ga(1)-Ga(1) bond lengths are 3.00 Å. All Ga(1)-Ga(2) bond lengths are 3.15 Å. In the second Ga site, Ga(2) is bonded in a square co-planar geometry to four equivalent Hg(1) and eight equivalent Ga(1) atoms.