SrCuLuSe3 crystallizes in the orthorhombic Cmcm space group. Sr(1) is bonded in a 8-coordinate geometry to two equivalent Se(2) and six equivalent Se(1) atoms. Lu(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form LuSe6 octahedra that share corners with two equivalent Lu(1)Se6 octahedra, edges with two equivalent Lu(1)Se6 octahedra, and edges with four equivalent Cu(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. Cu(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form CuSe4 tetrahedra that share corners with two equivalent Cu(1)Se4 tetrahedra and edges with four equivalent Lu(1)Se6 octahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to three equivalent Sr(1), two equivalent Lu(1), and one Cu(1) atom. In the second Se site, Se(2) is bonded to two equivalent Sr(1), two equivalent Lu(1), and two equivalent Cu(1) atoms to form a mixture of distorted edge and corner-sharing SeSr2Lu2Cu2 octahedra. The corner-sharing octahedra are not tilted.
SrCuLuSe3 crystallizes in the orthorhombic Cmcm space group. Sr(1) is bonded in a 8-coordinate geometry to two equivalent Se(2) and six equivalent Se(1) atoms. Both Sr(1)-Se(2) bond lengths are 3.11 Å. There are four shorter (3.20 Å) and two longer (3.60 Å) Sr(1)-Se(1) bond lengths. Lu(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form LuSe6 octahedra that share corners with two equivalent Lu(1)Se6 octahedra, edges with two equivalent Lu(1)Se6 octahedra, and edges with four equivalent Cu(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. Both Lu(1)-Se(2) bond lengths are 2.81 Å. All Lu(1)-Se(1) bond lengths are 2.83 Å. Cu(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form CuSe4 tetrahedra that share corners with two equivalent Cu(1)Se4 tetrahedra and edges with four equivalent Lu(1)Se6 octahedra. Both Cu(1)-Se(1) bond lengths are 2.46 Å. Both Cu(1)-Se(2) bond lengths are 2.49 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to three equivalent Sr(1), two equivalent Lu(1), and one Cu(1) atom. In the second Se site, Se(2) is bonded to two equivalent Sr(1), two equivalent Lu(1), and two equivalent Cu(1) atoms to form a mixture of distorted edge and corner-sharing SeSr2Lu2Cu2 octahedra. The corner-sharing octahedra are not tilted.