Cu7Hg6 crystallizes in the trigonal R3m space group. There are six inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to three equivalent Cu(3), three equivalent Cu(4), three equivalent Cu(5), and three equivalent Cu(6) atoms to form CuCu12 cuboctahedra that share faces with two equivalent Cu(2)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(3)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(5)Cu7Hg5 cuboctahedra, and faces with three equivalent Cu(6)Cu7Hg5 cuboctahedra. In the second Cu site, Cu(2) is bonded to three equivalent Cu(5), three equivalent Cu(6), three equivalent Hg(2), and three equivalent Hg(3) atoms to form CuCu6Hg6 cuboctahedra that share corners with six equivalent Cu(3)Cu6Hg6 cuboctahedra, corners with six equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(1)Cu12 cuboctahedra, faces with three equivalent Cu(3)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(5)Cu7Hg5 cuboctahedra, and faces with three equivalent Cu(6)Cu7Hg5 cuboctahedra. In the third Cu site, Cu(3) is bonded to one Cu(1), one Cu(6), two equivalent Cu(4), two equivalent Cu(5), one Hg(2), one Hg(3), and four equivalent Hg(1) atoms to form distorted CuCu6Hg6 cuboctahedra that share corners with two equivalent Cu(2)Cu6Hg6 cuboctahedra, corners with three equivalent Cu(4)Cu6Hg6 cuboctahedra, corners with four equivalent Cu(3)Cu6Hg6 cuboctahedra, corners with five equivalent Cu(6)Cu7Hg5 cuboctahedra, edges with two equivalent Cu(4)Cu6Hg6 cuboctahedra,  a faceface with one Cu(1)Cu12 cuboctahedra,  a faceface with one Cu(2)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(3)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(6)Cu7Hg5 cuboctahedra, and faces with four equivalent Cu(5)Cu7Hg5 cuboctahedra. In the fourth Cu site, Cu(4) is bonded to one Cu(1), one Cu(5), two equivalent Cu(3), two equivalent Cu(6), one Hg(2), one Hg(3), and four equivalent Hg(1) atoms to form distorted CuCu6Hg6 cuboctahedra that share corners with two equivalent Cu(2)Cu6Hg6 cuboctahedra, corners with three equivalent Cu(3)Cu6Hg6 cuboctahedra, corners with four equivalent Cu(4)Cu6Hg6 cuboctahedra, corners with five equivalent Cu(5)Cu7Hg5 cuboctahedra, edges with two equivalent Cu(3)Cu6Hg6 cuboctahedra,  a faceface with one Cu(1)Cu12 cuboctahedra,  a faceface with one Cu(2)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(3)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(5)Cu7Hg5 cuboctahedra, and faces with four equivalent Cu(6)Cu7Hg5 cuboctahedra. In the fifth Cu site, Cu(5) is bonded to one Cu(1), one Cu(2), one Cu(4), two equivalent Cu(3), two equivalent Cu(5), one Hg(2), two equivalent Hg(1), and two equivalent Hg(3) atoms to form distorted CuCu7Hg5 cuboctahedra that share corners with two equivalent Cu(6)Cu7Hg5 cuboctahedra, corners with five equivalent Cu(4)Cu6Hg6 cuboctahedra,  an edgeedge with one Cu(6)Cu7Hg5 cuboctahedra,  a faceface with one Cu(1)Cu12 cuboctahedra,  a faceface with one Cu(2)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(5)Cu7Hg5 cuboctahedra, faces with three equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with four equivalent Cu(3)Cu6Hg6 cuboctahedra, and faces with four equivalent Cu(6)Cu7Hg5 cuboctahedra. In the sixth Cu site, Cu(6) is bonded to one Cu(1), one Cu(2), one Cu(3), two equivalent Cu(4), two equivalent Cu(6), one Hg(3), two equivalent Hg(1), and two equivalent Hg(2) atoms to form distorted CuCu7Hg5 cuboctahedra that share corners with two equivalent Cu(5)Cu7Hg5 cuboctahedra, corners with five equivalent Cu(3)Cu6Hg6 cuboctahedra,  an edgeedge with one Cu(5)Cu7Hg5 cuboctahedra,  a faceface with one Cu(1)Cu12 cuboctahedra,  a faceface with one Cu(2)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(6)Cu7Hg5 cuboctahedra, faces with three equivalent Cu(3)Cu6Hg6 cuboctahedra, faces with four equivalent Cu(4)Cu6Hg6 cuboctahedra, and faces with four equivalent Cu(5)Cu7Hg5 cuboctahedra. There are three inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a 11-coordinate geometry to one Cu(5), one Cu(6), two equivalent Cu(3), two equivalent Cu(4), one Hg(2), one Hg(3), and three equivalent Hg(1) atoms. In the second Hg site, Hg(2) is bonded in a 11-coordinate geometry to one Cu(2), one Cu(3), one Cu(4), one Cu(5), two equivalent Cu(6), two equivalent Hg(1), and three equivalent Hg(3) atoms. In the third Hg site, Hg(3) is bonded in a 11-coordinate geometry to one Cu(2), one Cu(3), one Cu(4), one Cu(6), two equivalent Cu(5), two equivalent Hg(1), and three equivalent Hg(2) atoms.
Cu7Hg6 crystallizes in the trigonal R3m space group. There are six inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to three equivalent Cu(3), three equivalent Cu(4), three equivalent Cu(5), and three equivalent Cu(6) atoms to form CuCu12 cuboctahedra that share faces with two equivalent Cu(2)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(3)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(5)Cu7Hg5 cuboctahedra, and faces with three equivalent Cu(6)Cu7Hg5 cuboctahedra. All Cu(1)-Cu(3) bond lengths are 2.57 Å. All Cu(1)-Cu(4) bond lengths are 2.57 Å. All Cu(1)-Cu(5) bond lengths are 2.52 Å. All Cu(1)-Cu(6) bond lengths are 2.51 Å. In the second Cu site, Cu(2) is bonded to three equivalent Cu(5), three equivalent Cu(6), three equivalent Hg(2), and three equivalent Hg(3) atoms to form CuCu6Hg6 cuboctahedra that share corners with six equivalent Cu(3)Cu6Hg6 cuboctahedra, corners with six equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(1)Cu12 cuboctahedra, faces with three equivalent Cu(3)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(5)Cu7Hg5 cuboctahedra, and faces with three equivalent Cu(6)Cu7Hg5 cuboctahedra. All Cu(2)-Cu(5) bond lengths are 2.61 Å. All Cu(2)-Cu(6) bond lengths are 2.61 Å. All Cu(2)-Hg(2) bond lengths are 2.82 Å. All Cu(2)-Hg(3) bond lengths are 2.82 Å. In the third Cu site, Cu(3) is bonded to one Cu(1), one Cu(6), two equivalent Cu(4), two equivalent Cu(5), one Hg(2), one Hg(3), and four equivalent Hg(1) atoms to form distorted CuCu6Hg6 cuboctahedra that share corners with two equivalent Cu(2)Cu6Hg6 cuboctahedra, corners with three equivalent Cu(4)Cu6Hg6 cuboctahedra, corners with four equivalent Cu(3)Cu6Hg6 cuboctahedra, corners with five equivalent Cu(6)Cu7Hg5 cuboctahedra, edges with two equivalent Cu(4)Cu6Hg6 cuboctahedra,  a faceface with one Cu(1)Cu12 cuboctahedra,  a faceface with one Cu(2)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(3)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(6)Cu7Hg5 cuboctahedra, and faces with four equivalent Cu(5)Cu7Hg5 cuboctahedra. The Cu(3)-Cu(6) bond length is 2.70 Å. Both Cu(3)-Cu(4) bond lengths are 2.73 Å. Both Cu(3)-Cu(5) bond lengths are 2.63 Å. The Cu(3)-Hg(2) bond length is 2.91 Å. The Cu(3)-Hg(3) bond length is 3.05 Å. There are two shorter (2.81 Å) and two longer (2.86 Å) Cu(3)-Hg(1) bond lengths. In the fourth Cu site, Cu(4) is bonded to one Cu(1), one Cu(5), two equivalent Cu(3), two equivalent Cu(6), one Hg(2), one Hg(3), and four equivalent Hg(1) atoms to form distorted CuCu6Hg6 cuboctahedra that share corners with two equivalent Cu(2)Cu6Hg6 cuboctahedra, corners with three equivalent Cu(3)Cu6Hg6 cuboctahedra, corners with four equivalent Cu(4)Cu6Hg6 cuboctahedra, corners with five equivalent Cu(5)Cu7Hg5 cuboctahedra, edges with two equivalent Cu(3)Cu6Hg6 cuboctahedra,  a faceface with one Cu(1)Cu12 cuboctahedra,  a faceface with one Cu(2)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(3)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with three equivalent Cu(5)Cu7Hg5 cuboctahedra, and faces with four equivalent Cu(6)Cu7Hg5 cuboctahedra. The Cu(4)-Cu(5) bond length is 2.69 Å. Both Cu(4)-Cu(6) bond lengths are 2.64 Å. The Cu(4)-Hg(2) bond length is 3.04 Å. The Cu(4)-Hg(3) bond length is 2.91 Å. There are two shorter (2.81 Å) and two longer (2.88 Å) Cu(4)-Hg(1) bond lengths. In the fifth Cu site, Cu(5) is bonded to one Cu(1), one Cu(2), one Cu(4), two equivalent Cu(3), two equivalent Cu(5), one Hg(2), two equivalent Hg(1), and two equivalent Hg(3) atoms to form distorted CuCu7Hg5 cuboctahedra that share corners with two equivalent Cu(6)Cu7Hg5 cuboctahedra, corners with five equivalent Cu(4)Cu6Hg6 cuboctahedra,  an edgeedge with one Cu(6)Cu7Hg5 cuboctahedra,  a faceface with one Cu(1)Cu12 cuboctahedra,  a faceface with one Cu(2)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(5)Cu7Hg5 cuboctahedra, faces with three equivalent Cu(4)Cu6Hg6 cuboctahedra, faces with four equivalent Cu(3)Cu6Hg6 cuboctahedra, and faces with four equivalent Cu(6)Cu7Hg5 cuboctahedra. Both Cu(5)-Cu(5) bond lengths are 2.66 Å. The Cu(5)-Hg(2) bond length is 2.92 Å. Both Cu(5)-Hg(1) bond lengths are 2.90 Å. Both Cu(5)-Hg(3) bond lengths are 2.88 Å. In the sixth Cu site, Cu(6) is bonded to one Cu(1), one Cu(2), one Cu(3), two equivalent Cu(4), two equivalent Cu(6), one Hg(3), two equivalent Hg(1), and two equivalent Hg(2) atoms to form distorted CuCu7Hg5 cuboctahedra that share corners with two equivalent Cu(5)Cu7Hg5 cuboctahedra, corners with five equivalent Cu(3)Cu6Hg6 cuboctahedra,  an edgeedge with one Cu(5)Cu7Hg5 cuboctahedra,  a faceface with one Cu(1)Cu12 cuboctahedra,  a faceface with one Cu(2)Cu6Hg6 cuboctahedra, faces with two equivalent Cu(6)Cu7Hg5 cuboctahedra, faces with three equivalent Cu(3)Cu6Hg6 cuboctahedra, faces with four equivalent Cu(4)Cu6Hg6 cuboctahedra, and faces with four equivalent Cu(5)Cu7Hg5 cuboctahedra. Both Cu(6)-Cu(6) bond lengths are 2.67 Å. The Cu(6)-Hg(3) bond length is 2.91 Å. Both Cu(6)-Hg(1) bond lengths are 2.91 Å. Both Cu(6)-Hg(2) bond lengths are 2.87 Å. There are three inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a 11-coordinate geometry to one Cu(5), one Cu(6), two equivalent Cu(3), two equivalent Cu(4), one Hg(2), one Hg(3), and three equivalent Hg(1) atoms. The Hg(1)-Hg(2) bond length is 3.23 Å. The Hg(1)-Hg(3) bond length is 3.23 Å. There are two shorter (3.01 Å) and one longer (3.05 Å) Hg(1)-Hg(1) bond length. In the second Hg site, Hg(2) is bonded in a 11-coordinate geometry to one Cu(2), one Cu(3), one Cu(4), one Cu(5), two equivalent Cu(6), two equivalent Hg(1), and three equivalent Hg(3) atoms. There is one shorter (2.84 Å) and two longer (2.97 Å) Hg(2)-Hg(3) bond lengths. In the third Hg site, Hg(3) is bonded in a 11-coordinate geometry to one Cu(2), one Cu(3), one Cu(4), one Cu(6), two equivalent Cu(5), two equivalent Hg(1), and three equivalent Hg(2) atoms.