Tb(AlC)3 crystallizes in the hexagonal P6_3/mmc space group. Tb(1) is bonded to six equivalent C(1) atoms to form TbC6 octahedra that share corners with six equivalent Al(1)C4 tetrahedra, edges with six equivalent Tb(1)C6 octahedra, and edges with six equivalent Al(1)C4 tetrahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(2) and three equivalent C(1) atoms to form AlC4 tetrahedra that share corners with three equivalent Tb(1)C6 octahedra, corners with seven equivalent Al(1)C4 tetrahedra, and edges with three equivalent Tb(1)C6 octahedra. The corner-sharing octahedral tilt angles are 20°. In the second Al site, Al(2) is bonded in a trigonal planar geometry to three equivalent C(2) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded in a 6-coordinate geometry to three equivalent Tb(1) and three equivalent Al(1) atoms. In the second C site, C(2) is bonded to two equivalent Al(1) and three equivalent Al(2) atoms to form corner-sharing CAl5 trigonal bipyramids.
Tb(AlC)3 crystallizes in the hexagonal P6_3/mmc space group. Tb(1) is bonded to six equivalent C(1) atoms to form TbC6 octahedra that share corners with six equivalent Al(1)C4 tetrahedra, edges with six equivalent Tb(1)C6 octahedra, and edges with six equivalent Al(1)C4 tetrahedra. All Tb(1)-C(1) bond lengths are 2.56 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(2) and three equivalent C(1) atoms to form AlC4 tetrahedra that share corners with three equivalent Tb(1)C6 octahedra, corners with seven equivalent Al(1)C4 tetrahedra, and edges with three equivalent Tb(1)C6 octahedra. The corner-sharing octahedral tilt angles are 20°. The Al(1)-C(2) bond length is 2.00 Å. All Al(1)-C(1) bond lengths are 2.10 Å. In the second Al site, Al(2) is bonded in a trigonal planar geometry to three equivalent C(2) atoms. All Al(2)-C(2) bond lengths are 1.98 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a 6-coordinate geometry to three equivalent Tb(1) and three equivalent Al(1) atoms. In the second C site, C(2) is bonded to two equivalent Al(1) and three equivalent Al(2) atoms to form corner-sharing CAl5 trigonal bipyramids.