YbAl3C3 crystallizes in the hexagonal P6_3mc space group. Yb(1) is bonded to three equivalent C(2) and three equivalent C(3) atoms to form distorted YbC6 octahedra that share corners with three equivalent Al(1)C4 tetrahedra, corners with three equivalent Al(2)C4 tetrahedra, edges with six equivalent Yb(1)C6 octahedra, edges with three equivalent Al(1)C4 tetrahedra, and edges with three equivalent Al(2)C4 tetrahedra. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(1) and three equivalent C(2) atoms to form AlC4 tetrahedra that share corners with three equivalent Yb(1)C6 octahedra,  a cornercorner with one Al(2)C4 tetrahedra, corners with six equivalent Al(1)C4 tetrahedra, and edges with three equivalent Yb(1)C6 octahedra. The corner-sharing octahedral tilt angles are 26°. In the second Al site, Al(2) is bonded to one C(1) and three equivalent C(3) atoms to form AlC4 tetrahedra that share corners with three equivalent Yb(1)C6 octahedra,  a cornercorner with one Al(1)C4 tetrahedra, corners with six equivalent Al(2)C4 tetrahedra, and edges with three equivalent Yb(1)C6 octahedra. The corner-sharing octahedral tilt angles are 23°. In the third Al site, Al(3) is bonded in a distorted trigonal planar geometry to one C(2) and three equivalent C(1) atoms. There are three inequivalent C sites. In the first C site, C(1) is bonded to one Al(1), one Al(2), and three equivalent Al(3) atoms to form corner-sharing CAl5 trigonal bipyramids. In the second C site, C(2) is bonded in a 7-coordinate geometry to three equivalent Yb(1), one Al(3), and three equivalent Al(1) atoms. In the third C site, C(3) is bonded in a 6-coordinate geometry to three equivalent Yb(1) and three equivalent Al(2) atoms.
YbAl3C3 crystallizes in the hexagonal P6_3mc space group. Yb(1) is bonded to three equivalent C(2) and three equivalent C(3) atoms to form distorted YbC6 octahedra that share corners with three equivalent Al(1)C4 tetrahedra, corners with three equivalent Al(2)C4 tetrahedra, edges with six equivalent Yb(1)C6 octahedra, edges with three equivalent Al(1)C4 tetrahedra, and edges with three equivalent Al(2)C4 tetrahedra. All Yb(1)-C(2) bond lengths are 2.65 Å. All Yb(1)-C(3) bond lengths are 2.61 Å. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(1) and three equivalent C(2) atoms to form AlC4 tetrahedra that share corners with three equivalent Yb(1)C6 octahedra,  a cornercorner with one Al(2)C4 tetrahedra, corners with six equivalent Al(1)C4 tetrahedra, and edges with three equivalent Yb(1)C6 octahedra. The corner-sharing octahedral tilt angles are 26°. The Al(1)-C(1) bond length is 2.05 Å. All Al(1)-C(2) bond lengths are 2.06 Å. In the second Al site, Al(2) is bonded to one C(1) and three equivalent C(3) atoms to form AlC4 tetrahedra that share corners with three equivalent Yb(1)C6 octahedra,  a cornercorner with one Al(1)C4 tetrahedra, corners with six equivalent Al(2)C4 tetrahedra, and edges with three equivalent Yb(1)C6 octahedra. The corner-sharing octahedral tilt angles are 23°. The Al(2)-C(1) bond length is 2.03 Å. All Al(2)-C(3) bond lengths are 2.08 Å. In the third Al site, Al(3) is bonded in a distorted trigonal planar geometry to one C(2) and three equivalent C(1) atoms. The Al(3)-C(2) bond length is 2.54 Å. All Al(3)-C(1) bond lengths are 1.98 Å. There are three inequivalent C sites. In the first C site, C(1) is bonded to one Al(1), one Al(2), and three equivalent Al(3) atoms to form corner-sharing CAl5 trigonal bipyramids. In the second C site, C(2) is bonded in a 7-coordinate geometry to three equivalent Yb(1), one Al(3), and three equivalent Al(1) atoms. In the third C site, C(3) is bonded in a 6-coordinate geometry to three equivalent Yb(1) and three equivalent Al(2) atoms.