Al5C3N is Aluminum carbonitride-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent C(1) and three equivalent N(1) atoms to form AlC2N3 trigonal bipyramids that share corners with two equivalent Al(3)C4 tetrahedra, corners with six equivalent Al(1)C2N3 trigonal bipyramids, and edges with six equivalent Al(2)C3N trigonal pyramids. In the second Al site, Al(2) is bonded to three equivalent C(1) and one N(1) atom to form AlC3N trigonal pyramids that share corners with three equivalent Al(3)C4 tetrahedra, corners with seven equivalent Al(2)C3N trigonal pyramids, and edges with three equivalent Al(1)C2N3 trigonal bipyramids. In the third Al site, Al(3) is bonded to one C(1) and three equivalent C(2) atoms to form distorted AlC4 tetrahedra that share corners with nine equivalent Al(3)C4 tetrahedra,  a cornercorner with one Al(1)C2N3 trigonal bipyramid, corners with three equivalent Al(2)C3N trigonal pyramids, and edges with three equivalent Al(3)C4 tetrahedra. There are two inequivalent C sites. In the first C site, C(1) is bonded to one Al(1), one Al(3), and three equivalent Al(2) atoms to form distorted CAl5 trigonal bipyramids that share corners with three equivalent C(2)Al6 octahedra, corners with seven equivalent C(1)Al5 trigonal bipyramids, and edges with three equivalent N(1)Al5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 62°. In the second C site, C(2) is bonded to six equivalent Al(3) atoms to form CAl6 octahedra that share corners with six equivalent C(1)Al5 trigonal bipyramids and edges with six equivalent C(2)Al6 octahedra. N(1) is bonded to two equivalent Al(2) and three equivalent Al(1) atoms to form NAl5 trigonal bipyramids that share corners with six equivalent N(1)Al5 trigonal bipyramids and edges with six equivalent C(1)Al5 trigonal bipyramids.
Al5C3N is Aluminum carbonitride-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent C(1) and three equivalent N(1) atoms to form AlC2N3 trigonal bipyramids that share corners with two equivalent Al(3)C4 tetrahedra, corners with six equivalent Al(1)C2N3 trigonal bipyramids, and edges with six equivalent Al(2)C3N trigonal pyramids. Both Al(1)-C(1) bond lengths are 2.34 Å. All Al(1)-N(1) bond lengths are 1.93 Å. In the second Al site, Al(2) is bonded to three equivalent C(1) and one N(1) atom to form AlC3N trigonal pyramids that share corners with three equivalent Al(3)C4 tetrahedra, corners with seven equivalent Al(2)C3N trigonal pyramids, and edges with three equivalent Al(1)C2N3 trigonal bipyramids. All Al(2)-C(1) bond lengths are 1.96 Å. The Al(2)-N(1) bond length is 2.00 Å. In the third Al site, Al(3) is bonded to one C(1) and three equivalent C(2) atoms to form distorted AlC4 tetrahedra that share corners with nine equivalent Al(3)C4 tetrahedra,  a cornercorner with one Al(1)C2N3 trigonal bipyramid, corners with three equivalent Al(2)C3N trigonal pyramids, and edges with three equivalent Al(3)C4 tetrahedra. The Al(3)-C(1) bond length is 1.88 Å. All Al(3)-C(2) bond lengths are 2.19 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded to one Al(1), one Al(3), and three equivalent Al(2) atoms to form distorted CAl5 trigonal bipyramids that share corners with three equivalent C(2)Al6 octahedra, corners with seven equivalent C(1)Al5 trigonal bipyramids, and edges with three equivalent N(1)Al5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 62°. In the second C site, C(2) is bonded to six equivalent Al(3) atoms to form CAl6 octahedra that share corners with six equivalent C(1)Al5 trigonal bipyramids and edges with six equivalent C(2)Al6 octahedra. N(1) is bonded to two equivalent Al(2) and three equivalent Al(1) atoms to form NAl5 trigonal bipyramids that share corners with six equivalent N(1)Al5 trigonal bipyramids and edges with six equivalent C(1)Al5 trigonal bipyramids.