Cu2CoGeSe4 is Stannite-like structured and crystallizes in the tetragonal I-4 space group. Co(1) is bonded to four equivalent Se(1) atoms to form CoSe4 tetrahedra that share corners with four equivalent Cu(1)Se4 tetrahedra, corners with four equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent Ge(1)Se4 tetrahedra. 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 Co(1)Se4 tetrahedra, corners with four equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent Ge(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 Co(1)Se4 tetrahedra, corners with four equivalent Cu(1)Se4 tetrahedra, and corners with four equivalent Ge(1)Se4 tetrahedra. Ge(1) is bonded to four equivalent Se(1) atoms to form GeSe4 tetrahedra that share corners with four equivalent Co(1)Se4 tetrahedra, corners with four equivalent Cu(1)Se4 tetrahedra, and corners with four equivalent Cu(2)Se4 tetrahedra. Se(1) is bonded to one Co(1), one Cu(1), one Cu(2), and one Ge(1) atom to form corner-sharing SeCoCu2Ge tetrahedra.
Cu2CoGeSe4 is Stannite-like structured and crystallizes in the tetragonal I-4 space group. Co(1) is bonded to four equivalent Se(1) atoms to form CoSe4 tetrahedra that share corners with four equivalent Cu(1)Se4 tetrahedra, corners with four equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent Ge(1)Se4 tetrahedra. All Co(1)-Se(1) bond lengths are 2.38 Å. 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 Co(1)Se4 tetrahedra, corners with four equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent Ge(1)Se4 tetrahedra. All Cu(1)-Se(1) bond lengths are 2.42 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 Co(1)Se4 tetrahedra, corners with four equivalent Cu(1)Se4 tetrahedra, and corners with four equivalent Ge(1)Se4 tetrahedra. All Cu(2)-Se(1) bond lengths are 2.43 Å. Ge(1) is bonded to four equivalent Se(1) atoms to form GeSe4 tetrahedra that share corners with four equivalent Co(1)Se4 tetrahedra, corners with four equivalent Cu(1)Se4 tetrahedra, and corners with four equivalent Cu(2)Se4 tetrahedra. All Ge(1)-Se(1) bond lengths are 2.47 Å. Se(1) is bonded to one Co(1), one Cu(1), one Cu(2), and one Ge(1) atom to form corner-sharing SeCoCu2Ge tetrahedra.