ScCuSe2 crystallizes in the trigonal P3m1 space group. Sc(1) is bonded to three equivalent Se(1) and three equivalent Se(2) atoms to form ScSe6 octahedra that share corners with six equivalent Cu(1)Se4 tetrahedra, edges with six equivalent Sc(1)Se6 octahedra, and edges with three equivalent Cu(1)Se4 tetrahedra. Cu(1) is bonded to one Se(1) and three equivalent Se(2) atoms to form CuSe4 tetrahedra that share corners with six equivalent Sc(1)Se6 octahedra, corners with six equivalent Cu(1)Se4 tetrahedra, and edges with three equivalent Sc(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 16-58°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Sc(1) and one Cu(1) atom to form distorted SeSc3Cu trigonal pyramids that share corners with six equivalent Se(2)Sc3Cu3 octahedra, corners with six equivalent Se(1)Sc3Cu trigonal pyramids, and edges with three equivalent Se(2)Sc3Cu3 octahedra. The corner-sharing octahedral tilt angles range from 4-70°. In the second Se site, Se(2) is bonded to three equivalent Sc(1) and three equivalent Cu(1) atoms to form SeSc3Cu3 octahedra that share corners with six equivalent Se(1)Sc3Cu trigonal pyramids, edges with six equivalent Se(2)Sc3Cu3 octahedra, and edges with three equivalent Se(1)Sc3Cu trigonal pyramids.
ScCuSe2 crystallizes in the trigonal P3m1 space group. Sc(1) is bonded to three equivalent Se(1) and three equivalent Se(2) atoms to form ScSe6 octahedra that share corners with six equivalent Cu(1)Se4 tetrahedra, edges with six equivalent Sc(1)Se6 octahedra, and edges with three equivalent Cu(1)Se4 tetrahedra. All Sc(1)-Se(1) bond lengths are 2.67 Å. All Sc(1)-Se(2) bond lengths are 2.80 Å. Cu(1) is bonded to one Se(1) and three equivalent Se(2) atoms to form CuSe4 tetrahedra that share corners with six equivalent Sc(1)Se6 octahedra, corners with six equivalent Cu(1)Se4 tetrahedra, and edges with three equivalent Sc(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 16-58°. The Cu(1)-Se(1) bond length is 2.39 Å. All Cu(1)-Se(2) bond lengths are 2.41 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Sc(1) and one Cu(1) atom to form distorted SeSc3Cu trigonal pyramids that share corners with six equivalent Se(2)Sc3Cu3 octahedra, corners with six equivalent Se(1)Sc3Cu trigonal pyramids, and edges with three equivalent Se(2)Sc3Cu3 octahedra. The corner-sharing octahedral tilt angles range from 4-70°. In the second Se site, Se(2) is bonded to three equivalent Sc(1) and three equivalent Cu(1) atoms to form SeSc3Cu3 octahedra that share corners with six equivalent Se(1)Sc3Cu trigonal pyramids, edges with six equivalent Se(2)Sc3Cu3 octahedra, and edges with three equivalent Se(1)Sc3Cu trigonal pyramids.