YbCu4Al crystallizes in the hexagonal P-6m2 space group. Yb(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 Yb(1), six equivalent Cu(2), and three equivalent Al(1) atoms to form CuYb3Al3Cu6 cuboctahedra that share corners with nine equivalent Al(1)Yb3Cu9 cuboctahedra, corners with twelve equivalent Cu(2)Yb4Al2Cu6 cuboctahedra, edges with six equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, faces with two equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, faces with three equivalent Al(1)Yb3Cu9 cuboctahedra, and faces with eighteen equivalent Cu(2)Yb4Al2Cu6 cuboctahedra. In the second Cu site, Cu(2) is bonded to four equivalent Yb(1), two equivalent Cu(1), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuYb4Al2Cu6 cuboctahedra that share corners with four equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, corners with four equivalent Al(1)Yb3Cu9 cuboctahedra, corners with sixteen equivalent Cu(2)Yb4Al2Cu6 cuboctahedra, edges with ten equivalent Cu(2)Yb4Al2Cu6 cuboctahedra, faces with six equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, faces with six equivalent Al(1)Yb3Cu9 cuboctahedra, and faces with ten equivalent Cu(2)Yb4Al2Cu6 cuboctahedra. Al(1) is bonded to three equivalent Yb(1), three equivalent Cu(1), and six equivalent Cu(2) atoms to form distorted AlYb3Cu9 cuboctahedra that share corners with nine equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, corners with twelve equivalent Cu(2)Yb4Al2Cu6 cuboctahedra, edges with six equivalent Al(1)Yb3Cu9 cuboctahedra, faces with two equivalent Al(1)Yb3Cu9 cuboctahedra, faces with three equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, and faces with eighteen equivalent Cu(2)Yb4Al2Cu6 cuboctahedra.
YbCu4Al crystallizes in the hexagonal P-6m2 space group. Yb(1) is bonded in a 18-coordinate geometry to three equivalent Cu(1), twelve equivalent Cu(2), and three equivalent Al(1) atoms. All Yb(1)-Cu(1) bond lengths are 2.97 Å. All Yb(1)-Cu(2) bond lengths are 3.27 Å. All Yb(1)-Al(1) bond lengths are 2.97 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to three equivalent Yb(1), six equivalent Cu(2), and three equivalent Al(1) atoms to form CuYb3Al3Cu6 cuboctahedra that share corners with nine equivalent Al(1)Yb3Cu9 cuboctahedra, corners with twelve equivalent Cu(2)Yb4Al2Cu6 cuboctahedra, edges with six equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, faces with two equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, faces with three equivalent Al(1)Yb3Cu9 cuboctahedra, and faces with eighteen equivalent Cu(2)Yb4Al2Cu6 cuboctahedra. All Cu(1)-Cu(2) bond lengths are 2.50 Å. All Cu(1)-Al(1) bond lengths are 2.97 Å. In the second Cu site, Cu(2) is bonded to four equivalent Yb(1), two equivalent Cu(1), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuYb4Al2Cu6 cuboctahedra that share corners with four equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, corners with four equivalent Al(1)Yb3Cu9 cuboctahedra, corners with sixteen equivalent Cu(2)Yb4Al2Cu6 cuboctahedra, edges with ten equivalent Cu(2)Yb4Al2Cu6 cuboctahedra, faces with six equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, faces with six equivalent Al(1)Yb3Cu9 cuboctahedra, and faces with ten equivalent Cu(2)Yb4Al2Cu6 cuboctahedra. There are two shorter (2.56 Å) and two longer (2.59 Å) Cu(2)-Cu(2) bond lengths. Both Cu(2)-Al(1) bond lengths are 2.51 Å. Al(1) is bonded to three equivalent Yb(1), three equivalent Cu(1), and six equivalent Cu(2) atoms to form distorted AlYb3Cu9 cuboctahedra that share corners with nine equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, corners with twelve equivalent Cu(2)Yb4Al2Cu6 cuboctahedra, edges with six equivalent Al(1)Yb3Cu9 cuboctahedra, faces with two equivalent Al(1)Yb3Cu9 cuboctahedra, faces with three equivalent Cu(1)Yb3Al3Cu6 cuboctahedra, and faces with eighteen equivalent Cu(2)Yb4Al2Cu6 cuboctahedra.