U3Cu2Sb3 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to three equivalent Sb(1) and three equivalent Sb(2) atoms to form a mixture of distorted edge and corner-sharing USb6 octahedra. The corner-sharing octahedra are not tilted. In the second U site, U(2) is bonded in a 12-coordinate geometry to six equivalent Cu(1) and six equivalent Sb(1) atoms. Cu(1) is bonded in a 6-coordinate geometry to three equivalent U(2) and three equivalent Sb(1) atoms. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 9-coordinate geometry to three equivalent U(1), three equivalent U(2), and three equivalent Cu(1) atoms. In the second Sb site, Sb(2) is bonded to six equivalent U(1) atoms to form edge-sharing SbU6 octahedra.
U3Cu2Sb3 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to three equivalent Sb(1) and three equivalent Sb(2) atoms to form a mixture of distorted edge and corner-sharing USb6 octahedra. The corner-sharing octahedra are not tilted. All U(1)-Sb(1) bond lengths are 3.13 Å. All U(1)-Sb(2) bond lengths are 3.10 Å. In the second U site, U(2) is bonded in a 12-coordinate geometry to six equivalent Cu(1) and six equivalent Sb(1) atoms. All U(2)-Cu(1) bond lengths are 2.91 Å. All U(2)-Sb(1) bond lengths are 3.26 Å. Cu(1) is bonded in a 6-coordinate geometry to three equivalent U(2) and three equivalent Sb(1) atoms. All Cu(1)-Sb(1) bond lengths are 2.62 Å. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 9-coordinate geometry to three equivalent U(1), three equivalent U(2), and three equivalent Cu(1) atoms. In the second Sb site, Sb(2) is bonded to six equivalent U(1) atoms to form edge-sharing SbU6 octahedra.