The crystal structure described by Al7C3N3 is Aluminum carbonitride-like structured and crystallizes in the hexagonal P6_3mc space group. There are seven inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(3) and three equivalent N(3) atoms to form AlCN3 tetrahedra that share corners with three equivalent Al(6)C3N tetrahedra, corners with three equivalent Al(3)C4 tetrahedra, corners with six equivalent Al(1)CN3 tetrahedra, and  a cornercorner with one Al(5)C4 trigonal pyramid. In the second Al site, Al(2) is bonded to one N(2) and three equivalent N(1) atoms to form AlN4 tetrahedra that share corners with three equivalent Al(4)C3N tetrahedra, corners with three equivalent Al(7)CN3 tetrahedra, and corners with six equivalent Al(2)N4 tetrahedra. In the third Al site, Al(3) is bonded to one C(1) and three equivalent C(3) atoms to form distorted AlC4 tetrahedra that share  a cornercorner with one Al(7)CN3 tetrahedra, corners with three equivalent Al(1)CN3 tetrahedra, corners with six equivalent Al(3)C4 tetrahedra, and edges with three equivalent Al(5)C4 trigonal pyramids. In the fourth Al site, Al(4) is bonded to three equivalent C(2) and one N(1) atom to form distorted AlC3N tetrahedra that share corners with three equivalent Al(6)C3N tetrahedra, corners with three equivalent Al(2)N4 tetrahedra, corners with six equivalent Al(4)C3N tetrahedra, and edges with three equivalent Al(6)C3N tetrahedra. In the fifth Al site, Al(5) is bonded to one C(3) and three equivalent C(1) atoms to form distorted AlC4 trigonal pyramids that share  a cornercorner with one Al(1)CN3 tetrahedra, corners with three equivalent Al(7)CN3 tetrahedra, corners with six equivalent Al(5)C4 trigonal pyramids, and edges with three equivalent Al(3)C4 tetrahedra. In the sixth Al site, Al(6) is bonded to three equivalent C(2) and one N(3) atom to form distorted AlC3N tetrahedra that share corners with three equivalent Al(4)C3N tetrahedra, corners with three equivalent Al(1)CN3 tetrahedra, corners with six equivalent Al(6)C3N tetrahedra, and edges with three equivalent Al(4)C3N tetrahedra. In the seventh Al site, Al(7) is bonded to one C(1) and three equivalent N(2) atoms to form AlCN3 tetrahedra that share  a cornercorner with one Al(3)C4 tetrahedra, corners with three equivalent Al(2)N4 tetrahedra, corners with six equivalent Al(7)CN3 tetrahedra, and corners with three equivalent Al(5)C4 trigonal pyramids. There are three inequivalent C sites. In the first C site, C(1) is bonded to one Al(3), one Al(7), and three equivalent Al(5) atoms to form distorted CAl5 trigonal bipyramids that share corners with three equivalent N(2)Al4 tetrahedra, corners with six equivalent C(1)Al5 trigonal bipyramids, and edges with three equivalent C(3)Al5 trigonal bipyramids. In the second C site, C(2) is bonded to three equivalent Al(4) and three equivalent Al(6) atoms to form CAl6 octahedra that share corners with three equivalent N(1)Al4 tetrahedra, corners with three equivalent N(3)Al4 tetrahedra, and edges with six equivalent C(2)Al6 octahedra. In the third C site, C(3) is bonded to one Al(1), one Al(5), and three equivalent Al(3) atoms to form distorted CAl5 trigonal bipyramids that share corners with three equivalent N(3)Al4 tetrahedra, corners with six equivalent C(3)Al5 trigonal bipyramids, and edges with three equivalent C(1)Al5 trigonal bipyramids. There are three inequivalent N sites. In the first N site, N(1) is bonded to one Al(4) and three equivalent Al(2) atoms to form NAl4 tetrahedra that share corners with three equivalent C(2)Al6 octahedra, corners with three equivalent N(2)Al4 tetrahedra, and corners with six equivalent N(1)Al4 tetrahedra. The corner-sharing octahedral tilt angles are 63°. In the second N site, N(2) is bonded to one Al(2) and three equivalent Al(7) atoms to form NAl4 tetrahedra that share corners with three equivalent N(1)Al4 tetrahedra, corners with six equivalent N(2)Al4 tetrahedra, and corners with three equivalent C(1)Al5 trigonal bipyramids. In the third N site, N(3) is bonded to one Al(6) and three equivalent Al(1) atoms to form NAl4 tetrahedra that share corners with three equivalent C(2)Al6 octahedra, corners with six equivalent N(3)Al4 tetrahedra, and corners with three equivalent C(3)Al5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 61°. is represented by the CIF card [CIF]
data_Al7(CN)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.251
_cell_length_b   3.251
_cell_length_c   32.079
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   293.689
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Al  Al0  1  0.000  0.000  0.111  1.0
  Al  Al1  1  0.000  0.000  0.892  1.0
  Al  Al2  1  0.000  0.000  0.611  1.0
  Al  Al3  1  0.667  0.333  0.184  1.0
  Al  Al4  1  0.667  0.333  0.470  1.0
  Al  Al5  1  0.000  0.000  0.741  1.0
  Al  Al6  1  0.667  0.333  0.032  1.0
  Al  Al7  1  0.667  0.333  0.313  1.0
  Al  Al8  1  0.000  0.000  0.392  1.0
  Al  Al9  1  0.333  0.667  0.970  1.0
  Al  Al10  1  0.333  0.667  0.532  1.0
  Al  Al11  1  0.333  0.667  0.813  1.0
  Al  Al12  1  0.333  0.667  0.684  1.0
  Al  Al13  1  0.000  0.000  0.241  1.0
  C  C14  1  0.333  0.667  0.752  1.0
  C  C15  1  0.000  0.000  1.000  1.0
  C  C16  1  0.667  0.333  0.252  1.0
  C  C17  1  0.000  0.000  0.500  1.0
  C  C18  1  0.000  0.000  0.171  1.0
  C  C19  1  0.000  0.000  0.671  1.0
  N  N20  1  0.667  0.333  0.412  1.0
  N  N21  1  0.333  0.667  0.912  1.0
  N  N22  1  0.000  0.000  0.834  1.0
  N  N23  1  0.000  0.000  0.334  1.0
  N  N24  1  0.333  0.667  0.589  1.0
  N  N25  1  0.667  0.333  0.089  1.0
[/CIF]
.
The crystal structure described by Al7C3N3 is Aluminum carbonitride-like structured and crystallizes in the hexagonal P6_3mc space group. There are seven inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(3) and three equivalent N(3) atoms to form AlCN3 tetrahedra that share corners with three equivalent Al(6)C3N tetrahedra, corners with three equivalent Al(3)C4 tetrahedra, corners with six equivalent Al(1)CN3 tetrahedra, and  a cornercorner with one Al(5)C4 trigonal pyramid. In the second Al site, Al(2) is bonded to one N(2) and three equivalent N(1) atoms to form AlN4 tetrahedra that share corners with three equivalent Al(4)C3N tetrahedra, corners with three equivalent Al(7)CN3 tetrahedra, and corners with six equivalent Al(2)N4 tetrahedra. In the third Al site, Al(3) is bonded to one C(1) and three equivalent C(3) atoms to form distorted AlC4 tetrahedra that share  a cornercorner with one Al(7)CN3 tetrahedra, corners with three equivalent Al(1)CN3 tetrahedra, corners with six equivalent Al(3)C4 tetrahedra, and edges with three equivalent Al(5)C4 trigonal pyramids. In the fourth Al site, Al(4) is bonded to three equivalent C(2) and one N(1) atom to form distorted AlC3N tetrahedra that share corners with three equivalent Al(6)C3N tetrahedra, corners with three equivalent Al(2)N4 tetrahedra, corners with six equivalent Al(4)C3N tetrahedra, and edges with three equivalent Al(6)C3N tetrahedra. In the fifth Al site, Al(5) is bonded to one C(3) and three equivalent C(1) atoms to form distorted AlC4 trigonal pyramids that share  a cornercorner with one Al(1)CN3 tetrahedra, corners with three equivalent Al(7)CN3 tetrahedra, corners with six equivalent Al(5)C4 trigonal pyramids, and edges with three equivalent Al(3)C4 tetrahedra. In the sixth Al site, Al(6) is bonded to three equivalent C(2) and one N(3) atom to form distorted AlC3N tetrahedra that share corners with three equivalent Al(4)C3N tetrahedra, corners with three equivalent Al(1)CN3 tetrahedra, corners with six equivalent Al(6)C3N tetrahedra, and edges with three equivalent Al(4)C3N tetrahedra. In the seventh Al site, Al(7) is bonded to one C(1) and three equivalent N(2) atoms to form AlCN3 tetrahedra that share  a cornercorner with one Al(3)C4 tetrahedra, corners with three equivalent Al(2)N4 tetrahedra, corners with six equivalent Al(7)CN3 tetrahedra, and corners with three equivalent Al(5)C4 trigonal pyramids. There are three inequivalent C sites. In the first C site, C(1) is bonded to one Al(3), one Al(7), and three equivalent Al(5) atoms to form distorted CAl5 trigonal bipyramids that share corners with three equivalent N(2)Al4 tetrahedra, corners with six equivalent C(1)Al5 trigonal bipyramids, and edges with three equivalent C(3)Al5 trigonal bipyramids. In the second C site, C(2) is bonded to three equivalent Al(4) and three equivalent Al(6) atoms to form CAl6 octahedra that share corners with three equivalent N(1)Al4 tetrahedra, corners with three equivalent N(3)Al4 tetrahedra, and edges with six equivalent C(2)Al6 octahedra. In the third C site, C(3) is bonded to one Al(1), one Al(5), and three equivalent Al(3) atoms to form distorted CAl5 trigonal bipyramids that share corners with three equivalent N(3)Al4 tetrahedra, corners with six equivalent C(3)Al5 trigonal bipyramids, and edges with three equivalent C(1)Al5 trigonal bipyramids. There are three inequivalent N sites. In the first N site, N(1) is bonded to one Al(4) and three equivalent Al(2) atoms to form NAl4 tetrahedra that share corners with three equivalent C(2)Al6 octahedra, corners with three equivalent N(2)Al4 tetrahedra, and corners with six equivalent N(1)Al4 tetrahedra. The corner-sharing octahedral tilt angles are 63°. In the second N site, N(2) is bonded to one Al(2) and three equivalent Al(7) atoms to form NAl4 tetrahedra that share corners with three equivalent N(1)Al4 tetrahedra, corners with six equivalent N(2)Al4 tetrahedra, and corners with three equivalent C(1)Al5 trigonal bipyramids. In the third N site, N(3) is bonded to one Al(6) and three equivalent Al(1) atoms to form NAl4 tetrahedra that share corners with three equivalent C(2)Al6 octahedra, corners with six equivalent N(3)Al4 tetrahedra, and corners with three equivalent C(3)Al5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 61°. is represented by the CIF card [CIF]
data_Al7(CN)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.251
_cell_length_b   3.251
_cell_length_c   32.079
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   293.689
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Al  Al0  1  0.000  0.000  0.111  1.0
  Al  Al1  1  0.000  0.000  0.892  1.0
  Al  Al2  1  0.000  0.000  0.611  1.0
  Al  Al3  1  0.667  0.333  0.184  1.0
  Al  Al4  1  0.667  0.333  0.470  1.0
  Al  Al5  1  0.000  0.000  0.741  1.0
  Al  Al6  1  0.667  0.333  0.032  1.0
  Al  Al7  1  0.667  0.333  0.313  1.0
  Al  Al8  1  0.000  0.000  0.392  1.0
  Al  Al9  1  0.333  0.667  0.970  1.0
  Al  Al10  1  0.333  0.667  0.532  1.0
  Al  Al11  1  0.333  0.667  0.813  1.0
  Al  Al12  1  0.333  0.667  0.684  1.0
  Al  Al13  1  0.000  0.000  0.241  1.0
  C  C14  1  0.333  0.667  0.752  1.0
  C  C15  1  0.000  0.000  1.000  1.0
  C  C16  1  0.667  0.333  0.252  1.0
  C  C17  1  0.000  0.000  0.500  1.0
  C  C18  1  0.000  0.000  0.171  1.0
  C  C19  1  0.000  0.000  0.671  1.0
  N  N20  1  0.667  0.333  0.412  1.0
  N  N21  1  0.333  0.667  0.912  1.0
  N  N22  1  0.000  0.000  0.834  1.0
  N  N23  1  0.000  0.000  0.334  1.0
  N  N24  1  0.333  0.667  0.589  1.0
  N  N25  1  0.667  0.333  0.089  1.0
[/CIF]
.