Al3BC3 crystallizes in the hexagonal P6_3cm space group. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(3), one C(4), and two equivalent C(2) atoms to form a mixture of edge and corner-sharing AlC4 tetrahedra. In the second Al site, Al(2) is bonded to one C(1), one C(3), and two equivalent C(5) atoms to form a mixture of edge and corner-sharing AlC4 tetrahedra. In the third Al site, Al(3) is bonded to one C(2) and three equivalent C(3) atoms to form a mixture of edge and corner-sharing AlC4 trigonal pyramids. In the fourth Al site, Al(4) is bonded to one C(1) and three equivalent C(3) atoms to form a mixture of edge and corner-sharing AlC4 trigonal pyramids. There are two inequivalent B sites. In the first B site, B(1) is bonded in a linear geometry to one C(1) and one C(4) atom. In the second B site, B(2) is bonded in a linear geometry to one C(2) and one C(5) atom. There are five inequivalent C sites. In the first C site, C(4) is bonded to three equivalent Al(1) and one B(1) atom to form CAl3B tetrahedra that share  a cornercorner with one C(1)Al4B trigonal bipyramid, corners with three equivalent C(3)Al5 trigonal bipyramids, and corners with six equivalent C(2)Al4B trigonal bipyramids. In the second C site, C(5) is bonded to three equivalent Al(2) and one B(2) atom to form CAl3B tetrahedra that share corners with three equivalent C(5)Al3B tetrahedra,  a cornercorner with one C(2)Al4B trigonal bipyramid, corners with three equivalent C(1)Al4B trigonal bipyramids, and corners with three equivalent C(3)Al5 trigonal bipyramids. In the third C site, C(1) is bonded to one Al(4), three equivalent Al(2), and one B(1) atom to form distorted CAl4B trigonal bipyramids that share  a cornercorner with one C(4)Al3B tetrahedra, corners with six equivalent C(5)Al3B tetrahedra, and edges with three equivalent C(3)Al5 trigonal bipyramids. In the fourth C site, C(2) is bonded to one Al(3), three equivalent Al(1), and one B(2) atom to form distorted CAl4B trigonal bipyramids that share  a cornercorner with one C(5)Al3B tetrahedra, corners with three equivalent C(4)Al3B tetrahedra, corners with three equivalent C(2)Al4B trigonal bipyramids, and edges with three equivalent C(3)Al5 trigonal bipyramids. In the fifth C site, C(3) is bonded to one Al(1), one Al(2), one Al(4), and two equivalent Al(3) atoms to form CAl5 trigonal bipyramids that share  a cornercorner with one C(4)Al3B tetrahedra, corners with two equivalent C(5)Al3B tetrahedra, corners with six equivalent C(3)Al5 trigonal bipyramids,  an edgeedge with one C(1)Al4B trigonal bipyramid, and edges with two equivalent C(2)Al4B trigonal bipyramids.
Al3BC3 crystallizes in the hexagonal P6_3cm space group. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(3), one C(4), and two equivalent C(2) atoms to form a mixture of edge and corner-sharing AlC4 tetrahedra. The Al(1)-C(3) bond length is 2.02 Å. The Al(1)-C(4) bond length is 2.00 Å. Both Al(1)-C(2) bond lengths are 2.05 Å. In the second Al site, Al(2) is bonded to one C(1), one C(3), and two equivalent C(5) atoms to form a mixture of edge and corner-sharing AlC4 tetrahedra. The Al(2)-C(1) bond length is 2.08 Å. The Al(2)-C(3) bond length is 2.02 Å. Both Al(2)-C(5) bond lengths are 2.02 Å. In the third Al site, Al(3) is bonded to one C(2) and three equivalent C(3) atoms to form a mixture of edge and corner-sharing AlC4 trigonal pyramids. The Al(3)-C(2) bond length is 2.23 Å. All Al(3)-C(3) bond lengths are 1.97 Å. In the fourth Al site, Al(4) is bonded to one C(1) and three equivalent C(3) atoms to form a mixture of edge and corner-sharing AlC4 trigonal pyramids. The Al(4)-C(1) bond length is 2.11 Å. All Al(4)-C(3) bond lengths are 1.98 Å. There are two inequivalent B sites. In the first B site, B(1) is bonded in a linear geometry to one C(1) and one C(4) atom. The B(1)-C(1) bond length is 1.42 Å. The B(1)-C(4) bond length is 1.44 Å. In the second B site, B(2) is bonded in a linear geometry to one C(2) and one C(5) atom. The B(2)-C(2) bond length is 1.44 Å. The B(2)-C(5) bond length is 1.43 Å. There are five inequivalent C sites. In the first C site, C(4) is bonded to three equivalent Al(1) and one B(1) atom to form CAl3B tetrahedra that share  a cornercorner with one C(1)Al4B trigonal bipyramid, corners with three equivalent C(3)Al5 trigonal bipyramids, and corners with six equivalent C(2)Al4B trigonal bipyramids. In the second C site, C(5) is bonded to three equivalent Al(2) and one B(2) atom to form CAl3B tetrahedra that share corners with three equivalent C(5)Al3B tetrahedra,  a cornercorner with one C(2)Al4B trigonal bipyramid, corners with three equivalent C(1)Al4B trigonal bipyramids, and corners with three equivalent C(3)Al5 trigonal bipyramids. In the third C site, C(1) is bonded to one Al(4), three equivalent Al(2), and one B(1) atom to form distorted CAl4B trigonal bipyramids that share  a cornercorner with one C(4)Al3B tetrahedra, corners with six equivalent C(5)Al3B tetrahedra, and edges with three equivalent C(3)Al5 trigonal bipyramids. In the fourth C site, C(2) is bonded to one Al(3), three equivalent Al(1), and one B(2) atom to form distorted CAl4B trigonal bipyramids that share  a cornercorner with one C(5)Al3B tetrahedra, corners with three equivalent C(4)Al3B tetrahedra, corners with three equivalent C(2)Al4B trigonal bipyramids, and edges with three equivalent C(3)Al5 trigonal bipyramids. In the fifth C site, C(3) is bonded to one Al(1), one Al(2), one Al(4), and two equivalent Al(3) atoms to form CAl5 trigonal bipyramids that share  a cornercorner with one C(4)Al3B tetrahedra, corners with two equivalent C(5)Al3B tetrahedra, corners with six equivalent C(3)Al5 trigonal bipyramids,  an edgeedge with one C(1)Al4B trigonal bipyramid, and edges with two equivalent C(2)Al4B trigonal bipyramids.