GaAl(CuSe2)2 is Stannite-like structured and crystallizes in the tetragonal I-4 space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to four equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with four equivalent Cu(2)Se4 tetrahedra, corners with four equivalent Ga(1)Se4 tetrahedra, and corners with four equivalent Al(1)Se4 tetrahedra. In the second Cu site, Cu(2) is bonded to four equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with four equivalent Cu(1)Se4 tetrahedra, corners with four equivalent Ga(1)Se4 tetrahedra, and corners with four equivalent Al(1)Se4 tetrahedra. Ga(1) is bonded to four equivalent Se(1) atoms to form GaSe4 tetrahedra that share corners with four equivalent Cu(1)Se4 tetrahedra, corners with four equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent Al(1)Se4 tetrahedra. Al(1) is bonded to four equivalent Se(1) atoms to form AlSe4 tetrahedra that share corners with four equivalent Cu(1)Se4 tetrahedra, corners with four equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent Ga(1)Se4 tetrahedra. Se(1) is bonded to one Cu(1), one Cu(2), one Ga(1), and one Al(1) atom to form corner-sharing SeAlGaCu2 tetrahedra.
GaAl(CuSe2)2 is Stannite-like structured and crystallizes in the tetragonal I-4 space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to four equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with four equivalent Cu(2)Se4 tetrahedra, corners with four equivalent Ga(1)Se4 tetrahedra, and corners with four equivalent Al(1)Se4 tetrahedra. All Cu(1)-Se(1) bond lengths are 2.43 Å. In the second Cu site, Cu(2) is bonded to four equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with four equivalent Cu(1)Se4 tetrahedra, corners with four equivalent Ga(1)Se4 tetrahedra, and corners with four equivalent Al(1)Se4 tetrahedra. All Cu(2)-Se(1) bond lengths are 2.43 Å. Ga(1) is bonded to four equivalent Se(1) atoms to form GaSe4 tetrahedra that share corners with four equivalent Cu(1)Se4 tetrahedra, corners with four equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent Al(1)Se4 tetrahedra. All Ga(1)-Se(1) bond lengths are 2.46 Å. Al(1) is bonded to four equivalent Se(1) atoms to form AlSe4 tetrahedra that share corners with four equivalent Cu(1)Se4 tetrahedra, corners with four equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent Ga(1)Se4 tetrahedra. All Al(1)-Se(1) bond lengths are 2.43 Å. Se(1) is bonded to one Cu(1), one Cu(2), one Ga(1), and one Al(1) atom to form corner-sharing SeAlGaCu2 tetrahedra.