HoGdAl6 crystallizes in the hexagonal P-6m2 space group. Ho(1) is bonded to six equivalent Al(1) and six equivalent Al(2) atoms to form distorted HoAl12 cuboctahedra that share corners with six equivalent Ho(1)Al12 cuboctahedra, faces with two equivalent Ho(1)Al12 cuboctahedra, and faces with six equivalent Gd(1)Al12 cuboctahedra. Gd(1) is bonded to six equivalent Al(1) and six equivalent Al(2) atoms to form distorted GdAl12 cuboctahedra that share corners with six equivalent Gd(1)Al12 cuboctahedra, faces with two equivalent Gd(1)Al12 cuboctahedra, and faces with six equivalent Ho(1)Al12 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 10-coordinate geometry to two equivalent Ho(1), two equivalent Gd(1), two equivalent Al(1), and four equivalent Al(2) atoms. In the second Al site, Al(2) is bonded in a 10-coordinate geometry to two equivalent Ho(1), two equivalent Gd(1), two equivalent Al(2), and four equivalent Al(1) atoms.
HoGdAl6 crystallizes in the hexagonal P-6m2 space group. Ho(1) is bonded to six equivalent Al(1) and six equivalent Al(2) atoms to form distorted HoAl12 cuboctahedra that share corners with six equivalent Ho(1)Al12 cuboctahedra, faces with two equivalent Ho(1)Al12 cuboctahedra, and faces with six equivalent Gd(1)Al12 cuboctahedra. All Ho(1)-Al(1) bond lengths are 3.07 Å. All Ho(1)-Al(2) bond lengths are 3.14 Å. Gd(1) is bonded to six equivalent Al(1) and six equivalent Al(2) atoms to form distorted GdAl12 cuboctahedra that share corners with six equivalent Gd(1)Al12 cuboctahedra, faces with two equivalent Gd(1)Al12 cuboctahedra, and faces with six equivalent Ho(1)Al12 cuboctahedra. All Gd(1)-Al(1) bond lengths are 3.14 Å. All Gd(1)-Al(2) bond lengths are 3.07 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 10-coordinate geometry to two equivalent Ho(1), two equivalent Gd(1), two equivalent Al(1), and four equivalent Al(2) atoms. Both Al(1)-Al(1) bond lengths are 2.74 Å. All Al(1)-Al(2) bond lengths are 2.79 Å. In the second Al site, Al(2) is bonded in a 10-coordinate geometry to two equivalent Ho(1), two equivalent Gd(1), two equivalent Al(2), and four equivalent Al(1) atoms. Both Al(2)-Al(2) bond lengths are 2.73 Å.