Cu4Zn(SnSe4)2 crystallizes in the monoclinic C2 space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form CuSe4 tetrahedra that share corners with two equivalent Cu(1)Se4 tetrahedra, corners with two equivalent Cu(2)Se4 tetrahedra, corners with three equivalent Zn(1)Se4 tetrahedra, and corners with four equivalent Sn(1)Se4 tetrahedra. In the second Cu site, Cu(2) is bonded to one Se(1), one Se(2), and two equivalent Se(4) atoms to form CuSe4 tetrahedra that share  a cornercorner with one Zn(1)Se4 tetrahedra, corners with two equivalent Cu(1)Se4 tetrahedra, corners with two equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent Sn(1)Se4 tetrahedra. Zn(1) is bonded to two equivalent Se(1) and two equivalent Se(3) atoms to form ZnSe4 tetrahedra that share corners with two equivalent Cu(2)Se4 tetrahedra, corners with four equivalent Sn(1)Se4 tetrahedra, and corners with six equivalent Cu(1)Se4 tetrahedra. Sn(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form SnSe4 tetrahedra that share corners with two equivalent Zn(1)Se4 tetrahedra, corners with four equivalent Cu(1)Se4 tetrahedra, and corners with four equivalent Cu(2)Se4 tetrahedra. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one Cu(1), one Cu(2), one Zn(1), and one Sn(1) atom to form corner-sharing SeZnCu2Sn tetrahedra. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one Cu(1), one Cu(2), and one Sn(1) atom. In the third Se site, Se(3) is bonded to two equivalent Cu(1), one Zn(1), and one Sn(1) atom to form corner-sharing SeZnCu2Sn tetrahedra. In the fourth Se site, Se(4) is bonded in a trigonal non-coplanar geometry to two equivalent Cu(2) and one Sn(1) atom.
Cu4Zn(SnSe4)2 crystallizes in the monoclinic C2 space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form CuSe4 tetrahedra that share corners with two equivalent Cu(1)Se4 tetrahedra, corners with two equivalent Cu(2)Se4 tetrahedra, corners with three equivalent Zn(1)Se4 tetrahedra, and corners with four equivalent Sn(1)Se4 tetrahedra. The Cu(1)-Se(1) bond length is 2.44 Å. The Cu(1)-Se(2) bond length is 2.35 Å. There is one shorter (2.42 Å) and one longer (2.43 Å) Cu(1)-Se(3) bond length. In the second Cu site, Cu(2) is bonded to one Se(1), one Se(2), and two equivalent Se(4) atoms to form CuSe4 tetrahedra that share  a cornercorner with one Zn(1)Se4 tetrahedra, corners with two equivalent Cu(1)Se4 tetrahedra, corners with two equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent Sn(1)Se4 tetrahedra. The Cu(2)-Se(1) bond length is 2.49 Å. The Cu(2)-Se(2) bond length is 2.40 Å. There is one shorter (2.40 Å) and one longer (2.42 Å) Cu(2)-Se(4) bond length. Zn(1) is bonded to two equivalent Se(1) and two equivalent Se(3) atoms to form ZnSe4 tetrahedra that share corners with two equivalent Cu(2)Se4 tetrahedra, corners with four equivalent Sn(1)Se4 tetrahedra, and corners with six equivalent Cu(1)Se4 tetrahedra. Both Zn(1)-Se(1) bond lengths are 2.49 Å. Both Zn(1)-Se(3) bond lengths are 2.48 Å. Sn(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form SnSe4 tetrahedra that share corners with two equivalent Zn(1)Se4 tetrahedra, corners with four equivalent Cu(1)Se4 tetrahedra, and corners with four equivalent Cu(2)Se4 tetrahedra. The Sn(1)-Se(1) bond length is 2.64 Å. The Sn(1)-Se(2) bond length is 2.57 Å. The Sn(1)-Se(3) bond length is 2.63 Å. The Sn(1)-Se(4) bond length is 2.56 Å. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one Cu(1), one Cu(2), one Zn(1), and one Sn(1) atom to form corner-sharing SeZnCu2Sn tetrahedra. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one Cu(1), one Cu(2), and one Sn(1) atom. In the third Se site, Se(3) is bonded to two equivalent Cu(1), one Zn(1), and one Sn(1) atom to form corner-sharing SeZnCu2Sn tetrahedra. In the fourth Se site, Se(4) is bonded in a trigonal non-coplanar geometry to two equivalent Cu(2) and one Sn(1) atom.