GdCu5Te4 crystallizes in the monoclinic C2/m space group. Gd(1) is bonded to two equivalent Te(2) and four equivalent Te(1) atoms to form GdTe6 octahedra that share corners with two equivalent Cu(2)Te4 tetrahedra, corners with ten equivalent Cu(3)Te4 tetrahedra, edges with two equivalent Gd(1)Te6 octahedra, edges with four equivalent Cu(1)Te6 octahedra, edges with two equivalent Cu(3)Te4 tetrahedra, and edges with four equivalent Cu(2)Te4 tetrahedra. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent Te(1) and four equivalent Te(2) atoms to form CuTe6 octahedra that share corners with two equivalent Cu(3)Te4 tetrahedra, corners with ten equivalent Cu(2)Te4 tetrahedra, edges with two equivalent Cu(1)Te6 octahedra, edges with four equivalent Gd(1)Te6 octahedra, edges with two equivalent Cu(2)Te4 tetrahedra, and edges with four equivalent Cu(3)Te4 tetrahedra. In the second Cu site, Cu(2) is bonded to one Te(1) and three equivalent Te(2) atoms to form distorted CuTe4 tetrahedra that share  a cornercorner with one Gd(1)Te6 octahedra, corners with five equivalent Cu(1)Te6 octahedra, corners with two equivalent Cu(2)Te4 tetrahedra, corners with four equivalent Cu(3)Te4 tetrahedra,  an edgeedge with one Cu(1)Te6 octahedra, edges with two equivalent Gd(1)Te6 octahedra,  an edgeedge with one Cu(3)Te4 tetrahedra, and edges with two equivalent Cu(2)Te4 tetrahedra. The corner-sharing octahedral tilt angles range from 12-56°. In the third Cu site, Cu(3) is bonded to one Te(2) and three equivalent Te(1) atoms to form distorted CuTe4 tetrahedra that share  a cornercorner with one Cu(1)Te6 octahedra, corners with five equivalent Gd(1)Te6 octahedra, corners with two equivalent Cu(3)Te4 tetrahedra, corners with four equivalent Cu(2)Te4 tetrahedra,  an edgeedge with one Gd(1)Te6 octahedra, edges with two equivalent Cu(1)Te6 octahedra,  an edgeedge with one Cu(2)Te4 tetrahedra, and edges with two equivalent Cu(3)Te4 tetrahedra. The corner-sharing octahedral tilt angles range from 8-57°. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded to two equivalent Gd(1), one Cu(1), one Cu(2), and three equivalent Cu(3) atoms to form distorted TeGd2Cu5 pentagonal bipyramids that share corners with three equivalent Te(1)Gd2Cu5 pentagonal bipyramids, edges with five equivalent Te(1)Gd2Cu5 pentagonal bipyramids, and edges with seven equivalent Te(2)GdCu6 pentagonal bipyramids. In the second Te site, Te(2) is bonded to one Gd(1), one Cu(3), two equivalent Cu(1), and three equivalent Cu(2) atoms to form distorted TeGdCu6 pentagonal bipyramids that share corners with three equivalent Te(2)GdCu6 pentagonal bipyramids, edges with five equivalent Te(2)GdCu6 pentagonal bipyramids, and edges with seven equivalent Te(1)Gd2Cu5 pentagonal bipyramids.
GdCu5Te4 crystallizes in the monoclinic C2/m space group. Gd(1) is bonded to two equivalent Te(2) and four equivalent Te(1) atoms to form GdTe6 octahedra that share corners with two equivalent Cu(2)Te4 tetrahedra, corners with ten equivalent Cu(3)Te4 tetrahedra, edges with two equivalent Gd(1)Te6 octahedra, edges with four equivalent Cu(1)Te6 octahedra, edges with two equivalent Cu(3)Te4 tetrahedra, and edges with four equivalent Cu(2)Te4 tetrahedra. Both Gd(1)-Te(2) bond lengths are 3.09 Å. All Gd(1)-Te(1) bond lengths are 3.06 Å. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent Te(1) and four equivalent Te(2) atoms to form CuTe6 octahedra that share corners with two equivalent Cu(3)Te4 tetrahedra, corners with ten equivalent Cu(2)Te4 tetrahedra, edges with two equivalent Cu(1)Te6 octahedra, edges with four equivalent Gd(1)Te6 octahedra, edges with two equivalent Cu(2)Te4 tetrahedra, and edges with four equivalent Cu(3)Te4 tetrahedra. Both Cu(1)-Te(1) bond lengths are 3.00 Å. All Cu(1)-Te(2) bond lengths are 2.94 Å. In the second Cu site, Cu(2) is bonded to one Te(1) and three equivalent Te(2) atoms to form distorted CuTe4 tetrahedra that share  a cornercorner with one Gd(1)Te6 octahedra, corners with five equivalent Cu(1)Te6 octahedra, corners with two equivalent Cu(2)Te4 tetrahedra, corners with four equivalent Cu(3)Te4 tetrahedra,  an edgeedge with one Cu(1)Te6 octahedra, edges with two equivalent Gd(1)Te6 octahedra,  an edgeedge with one Cu(3)Te4 tetrahedra, and edges with two equivalent Cu(2)Te4 tetrahedra. The corner-sharing octahedral tilt angles range from 12-56°. The Cu(2)-Te(1) bond length is 2.72 Å. There is one shorter (2.68 Å) and two longer (2.75 Å) Cu(2)-Te(2) bond lengths. In the third Cu site, Cu(3) is bonded to one Te(2) and three equivalent Te(1) atoms to form distorted CuTe4 tetrahedra that share  a cornercorner with one Cu(1)Te6 octahedra, corners with five equivalent Gd(1)Te6 octahedra, corners with two equivalent Cu(3)Te4 tetrahedra, corners with four equivalent Cu(2)Te4 tetrahedra,  an edgeedge with one Gd(1)Te6 octahedra, edges with two equivalent Cu(1)Te6 octahedra,  an edgeedge with one Cu(2)Te4 tetrahedra, and edges with two equivalent Cu(3)Te4 tetrahedra. The corner-sharing octahedral tilt angles range from 8-57°. The Cu(3)-Te(2) bond length is 2.62 Å. There is one shorter (2.59 Å) and two longer (2.63 Å) Cu(3)-Te(1) bond lengths. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded to two equivalent Gd(1), one Cu(1), one Cu(2), and three equivalent Cu(3) atoms to form distorted TeGd2Cu5 pentagonal bipyramids that share corners with three equivalent Te(1)Gd2Cu5 pentagonal bipyramids, edges with five equivalent Te(1)Gd2Cu5 pentagonal bipyramids, and edges with seven equivalent Te(2)GdCu6 pentagonal bipyramids. In the second Te site, Te(2) is bonded to one Gd(1), one Cu(3), two equivalent Cu(1), and three equivalent Cu(2) atoms to form distorted TeGdCu6 pentagonal bipyramids that share corners with three equivalent Te(2)GdCu6 pentagonal bipyramids, edges with five equivalent Te(2)GdCu6 pentagonal bipyramids, and edges with seven equivalent Te(1)Gd2Cu5 pentagonal bipyramids.