TbCu4Al crystallizes in the hexagonal P-6m2 space group. Tb(1) is bonded in a 18-coordinate geometry to three equivalent Cu(1), twelve equivalent Cu(2), and three equivalent Al(1) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to three equivalent Tb(1), six equivalent Cu(2), and three equivalent Al(1) atoms to form CuTb3Al3Cu6 cuboctahedra that share corners with nine equivalent Al(1)Tb3Cu9 cuboctahedra, corners with twelve equivalent Cu(2)Tb4Al2Cu6 cuboctahedra, edges with six equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, faces with two equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, faces with three equivalent Al(1)Tb3Cu9 cuboctahedra, and faces with eighteen equivalent Cu(2)Tb4Al2Cu6 cuboctahedra. In the second Cu site, Cu(2) is bonded to four equivalent Tb(1), two equivalent Cu(1), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuTb4Al2Cu6 cuboctahedra that share corners with four equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, corners with four equivalent Al(1)Tb3Cu9 cuboctahedra, corners with sixteen equivalent Cu(2)Tb4Al2Cu6 cuboctahedra, edges with ten equivalent Cu(2)Tb4Al2Cu6 cuboctahedra, faces with six equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, faces with six equivalent Al(1)Tb3Cu9 cuboctahedra, and faces with ten equivalent Cu(2)Tb4Al2Cu6 cuboctahedra. Al(1) is bonded to three equivalent Tb(1), three equivalent Cu(1), and six equivalent Cu(2) atoms to form distorted AlTb3Cu9 cuboctahedra that share corners with nine equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, corners with twelve equivalent Cu(2)Tb4Al2Cu6 cuboctahedra, edges with six equivalent Al(1)Tb3Cu9 cuboctahedra, faces with two equivalent Al(1)Tb3Cu9 cuboctahedra, faces with three equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, and faces with eighteen equivalent Cu(2)Tb4Al2Cu6 cuboctahedra.
TbCu4Al crystallizes in the hexagonal P-6m2 space group. Tb(1) is bonded in a 18-coordinate geometry to three equivalent Cu(1), twelve equivalent Cu(2), and three equivalent Al(1) atoms. All Tb(1)-Cu(1) bond lengths are 2.99 Å. All Tb(1)-Cu(2) bond lengths are 3.28 Å. All Tb(1)-Al(1) bond lengths are 2.99 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to three equivalent Tb(1), six equivalent Cu(2), and three equivalent Al(1) atoms to form CuTb3Al3Cu6 cuboctahedra that share corners with nine equivalent Al(1)Tb3Cu9 cuboctahedra, corners with twelve equivalent Cu(2)Tb4Al2Cu6 cuboctahedra, edges with six equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, faces with two equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, faces with three equivalent Al(1)Tb3Cu9 cuboctahedra, and faces with eighteen equivalent Cu(2)Tb4Al2Cu6 cuboctahedra. All Cu(1)-Cu(2) bond lengths are 2.51 Å. All Cu(1)-Al(1) bond lengths are 2.99 Å. In the second Cu site, Cu(2) is bonded to four equivalent Tb(1), two equivalent Cu(1), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuTb4Al2Cu6 cuboctahedra that share corners with four equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, corners with four equivalent Al(1)Tb3Cu9 cuboctahedra, corners with sixteen equivalent Cu(2)Tb4Al2Cu6 cuboctahedra, edges with ten equivalent Cu(2)Tb4Al2Cu6 cuboctahedra, faces with six equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, faces with six equivalent Al(1)Tb3Cu9 cuboctahedra, and faces with ten equivalent Cu(2)Tb4Al2Cu6 cuboctahedra. There are two shorter (2.58 Å) and two longer (2.61 Å) Cu(2)-Cu(2) bond lengths. Both Cu(2)-Al(1) bond lengths are 2.52 Å. Al(1) is bonded to three equivalent Tb(1), three equivalent Cu(1), and six equivalent Cu(2) atoms to form distorted AlTb3Cu9 cuboctahedra that share corners with nine equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, corners with twelve equivalent Cu(2)Tb4Al2Cu6 cuboctahedra, edges with six equivalent Al(1)Tb3Cu9 cuboctahedra, faces with two equivalent Al(1)Tb3Cu9 cuboctahedra, faces with three equivalent Cu(1)Tb3Al3Cu6 cuboctahedra, and faces with eighteen equivalent Cu(2)Tb4Al2Cu6 cuboctahedra.