ErCuTl crystallizes in the monoclinic C2/m space group. Er(1) is bonded in a 9-coordinate geometry to six equivalent Cu(1) and three equivalent Tl(1) atoms. Cu(1) is bonded in a 9-coordinate geometry to six equivalent Er(1) and three equivalent Cu(1) atoms. Tl(1) is bonded to three equivalent Er(1) and three equivalent Tl(1) atoms to form edge-sharing TlEr3Tl3 octahedra.
ErCuTl crystallizes in the monoclinic C2/m space group. Er(1) is bonded in a 9-coordinate geometry to six equivalent Cu(1) and three equivalent Tl(1) atoms. There are a spread of Er(1)-Cu(1) bond distances ranging from 2.89-2.99 Å. There are two shorter (3.21 Å) and one longer (3.23 Å) Er(1)-Tl(1) bond length. Cu(1) is bonded in a 9-coordinate geometry to six equivalent Er(1) and three equivalent Cu(1) atoms. All Cu(1)-Cu(1) bond lengths are 2.45 Å. Tl(1) is bonded to three equivalent Er(1) and three equivalent Tl(1) atoms to form edge-sharing TlEr3Tl3 octahedra. There are two shorter (3.04 Å) and one longer (3.07 Å) Tl(1)-Tl(1) bond length.