SrCuLaSe3 crystallizes in the orthorhombic Pnma space group. Sr(1) is bonded in a 7-coordinate geometry to one Se(3), two equivalent Se(1), and four equivalent Se(2) atoms. La(1) is bonded in a 7-coordinate geometry to one Se(2), three equivalent Se(1), and three equivalent Se(3) atoms. Cu(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form corner-sharing CuSe4 tetrahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Sr(1), three equivalent La(1), and one Cu(1) atom to form distorted SeSr2La3Cu octahedra that share corners with six equivalent Se(2)Sr4LaCu octahedra, corners with seven equivalent Se(3)SrLa3Cu2 octahedra, edges with three equivalent Se(3)SrLa3Cu2 octahedra, edges with four equivalent Se(1)Sr2La3Cu octahedra, and faces with two equivalent Se(2)Sr4LaCu octahedra. The corner-sharing octahedral tilt angles range from 22-62°. In the second Se site, Se(2) is bonded to four equivalent Sr(1), one La(1), and one Cu(1) atom to form distorted SeSr4LaCu octahedra that share  a cornercorner with one Se(3)SrLa3Cu2 octahedra, corners with four equivalent Se(2)Sr4LaCu octahedra, corners with six equivalent Se(1)Sr2La3Cu octahedra, edges with four equivalent Se(2)Sr4LaCu octahedra, edges with four equivalent Se(3)SrLa3Cu2 octahedra, and faces with two equivalent Se(1)Sr2La3Cu octahedra. The corner-sharing octahedral tilt angles range from 22-62°. In the third Se site, Se(3) is bonded to one Sr(1), three equivalent La(1), and two equivalent Cu(1) atoms to form distorted SeSrLa3Cu2 octahedra that share  a cornercorner with one Se(2)Sr4LaCu octahedra, corners with seven equivalent Se(1)Sr2La3Cu octahedra, edges with three equivalent Se(1)Sr2La3Cu octahedra, edges with four equivalent Se(2)Sr4LaCu octahedra, and edges with four equivalent Se(3)SrLa3Cu2 octahedra. The corner-sharing octahedral tilt angles range from 22-53°.
SrCuLaSe3 crystallizes in the orthorhombic Pnma space group. Sr(1) is bonded in a 7-coordinate geometry to one Se(3), two equivalent Se(1), and four equivalent Se(2) atoms. The Sr(1)-Se(3) bond length is 3.20 Å. Both Sr(1)-Se(1) bond lengths are 3.32 Å. There are two shorter (3.12 Å) and two longer (3.15 Å) Sr(1)-Se(2) bond lengths. La(1) is bonded in a 7-coordinate geometry to one Se(2), three equivalent Se(1), and three equivalent Se(3) atoms. The La(1)-Se(2) bond length is 3.05 Å. There are two shorter (2.99 Å) and one longer (3.29 Å) La(1)-Se(1) bond length. There are two shorter (3.08 Å) and one longer (3.13 Å) La(1)-Se(3) bond length. Cu(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form corner-sharing CuSe4 tetrahedra. The Cu(1)-Se(1) bond length is 2.48 Å. The Cu(1)-Se(2) bond length is 2.49 Å. Both Cu(1)-Se(3) bond lengths are 2.50 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Sr(1), three equivalent La(1), and one Cu(1) atom to form distorted SeSr2La3Cu octahedra that share corners with six equivalent Se(2)Sr4LaCu octahedra, corners with seven equivalent Se(3)SrLa3Cu2 octahedra, edges with three equivalent Se(3)SrLa3Cu2 octahedra, edges with four equivalent Se(1)Sr2La3Cu octahedra, and faces with two equivalent Se(2)Sr4LaCu octahedra. The corner-sharing octahedral tilt angles range from 22-62°. In the second Se site, Se(2) is bonded to four equivalent Sr(1), one La(1), and one Cu(1) atom to form distorted SeSr4LaCu octahedra that share  a cornercorner with one Se(3)SrLa3Cu2 octahedra, corners with four equivalent Se(2)Sr4LaCu octahedra, corners with six equivalent Se(1)Sr2La3Cu octahedra, edges with four equivalent Se(2)Sr4LaCu octahedra, edges with four equivalent Se(3)SrLa3Cu2 octahedra, and faces with two equivalent Se(1)Sr2La3Cu octahedra. The corner-sharing octahedral tilt angles range from 22-62°. In the third Se site, Se(3) is bonded to one Sr(1), three equivalent La(1), and two equivalent Cu(1) atoms to form distorted SeSrLa3Cu2 octahedra that share  a cornercorner with one Se(2)Sr4LaCu octahedra, corners with seven equivalent Se(1)Sr2La3Cu octahedra, edges with three equivalent Se(1)Sr2La3Cu octahedra, edges with four equivalent Se(2)Sr4LaCu octahedra, and edges with four equivalent Se(3)SrLa3Cu2 octahedra. The corner-sharing octahedral tilt angles range from 22-53°.