TmEuCuS3 crystallizes in the orthorhombic Cmcm space group. Tm(1) is bonded to two equivalent S(1) and four equivalent S(2) atoms to form TmS6 octahedra that share corners with two equivalent Tm(1)S6 octahedra, edges with two equivalent Tm(1)S6 octahedra, and edges with four equivalent Cu(1)S4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. Eu(1) is bonded in a 6-coordinate geometry to two equivalent S(1) and six equivalent S(2) atoms. Cu(1) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form CuS4 tetrahedra that share corners with two equivalent Cu(1)S4 tetrahedra and edges with four equivalent Tm(1)S6 octahedra. There are two inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Tm(1), two equivalent Eu(1), and two equivalent Cu(1) atoms to form a mixture of distorted corner and edge-sharing SEu2Tm2Cu2 octahedra. The corner-sharing octahedra are not tilted. In the second S site, S(2) is bonded in a 6-coordinate geometry to two equivalent Tm(1), three equivalent Eu(1), and one Cu(1) atom.
TmEuCuS3 crystallizes in the orthorhombic Cmcm space group. Tm(1) is bonded to two equivalent S(1) and four equivalent S(2) atoms to form TmS6 octahedra that share corners with two equivalent Tm(1)S6 octahedra, edges with two equivalent Tm(1)S6 octahedra, and edges with four equivalent Cu(1)S4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. Both Tm(1)-S(1) bond lengths are 2.72 Å. All Tm(1)-S(2) bond lengths are 2.71 Å. Eu(1) is bonded in a 6-coordinate geometry to two equivalent S(1) and six equivalent S(2) atoms. Both Eu(1)-S(1) bond lengths are 2.93 Å. There are four shorter (3.02 Å) and two longer (3.52 Å) Eu(1)-S(2) bond lengths. Cu(1) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form CuS4 tetrahedra that share corners with two equivalent Cu(1)S4 tetrahedra and edges with four equivalent Tm(1)S6 octahedra. Both Cu(1)-S(1) bond lengths are 2.37 Å. Both Cu(1)-S(2) bond lengths are 2.33 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Tm(1), two equivalent Eu(1), and two equivalent Cu(1) atoms to form a mixture of distorted corner and edge-sharing SEu2Tm2Cu2 octahedra. The corner-sharing octahedra are not tilted. In the second S site, S(2) is bonded in a 6-coordinate geometry to two equivalent Tm(1), three equivalent Eu(1), and one Cu(1) atom.