SrCu3TlSe4 crystallizes in the cubic P-43m space group. Sr(1) is bonded to four equivalent Se(1) atoms to form SrSe4 tetrahedra that share corners with four equivalent Tl(1)Se4 tetrahedra and corners with twelve equivalent Cu(1)Se4 tetrahedra. Cu(1) is bonded to four equivalent Se(1) atoms to form distorted CuSe4 tetrahedra that share corners with four equivalent Sr(1)Se4 tetrahedra, corners with eight equivalent Cu(1)Se4 tetrahedra, and edges with two equivalent Tl(1)Se4 tetrahedra. Tl(1) is bonded to four equivalent Se(1) atoms to form TlSe4 tetrahedra that share corners with four equivalent Sr(1)Se4 tetrahedra and edges with six equivalent Cu(1)Se4 tetrahedra. Se(1) is bonded in a distorted pentagonal planar geometry to one Sr(1), three equivalent Cu(1), and one Tl(1) atom.
SrCu3TlSe4 crystallizes in the cubic P-43m space group. Sr(1) is bonded to four equivalent Se(1) atoms to form SrSe4 tetrahedra that share corners with four equivalent Tl(1)Se4 tetrahedra and corners with twelve equivalent Cu(1)Se4 tetrahedra. All Sr(1)-Se(1) bond lengths are 2.88 Å. Cu(1) is bonded to four equivalent Se(1) atoms to form distorted CuSe4 tetrahedra that share corners with four equivalent Sr(1)Se4 tetrahedra, corners with eight equivalent Cu(1)Se4 tetrahedra, and edges with two equivalent Tl(1)Se4 tetrahedra. All Cu(1)-Se(1) bond lengths are 2.69 Å. Tl(1) is bonded to four equivalent Se(1) atoms to form TlSe4 tetrahedra that share corners with four equivalent Sr(1)Se4 tetrahedra and edges with six equivalent Cu(1)Se4 tetrahedra. All Tl(1)-Se(1) bond lengths are 2.58 Å. Se(1) is bonded in a distorted pentagonal planar geometry to one Sr(1), three equivalent Cu(1), and one Tl(1) atom.