The material structure described by Nb20N17 crystallizes in the monoclinic C2/m space group. There are eight inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a square co-planar geometry to two equivalent N(4) and two equivalent N(5) atoms. In the second Nb site, Nb(2) is bonded to one N(1), one N(3), one N(5), one N(6), and one N(7) atom to form NbN5 square pyramids that share  a cornercorner with one Nb(6)N5 square pyramid,  a cornercorner with one Nb(7)N5 square pyramid, corners with two equivalent Nb(2)N5 square pyramids, corners with three equivalent Nb(3)N5 square pyramids, edges with two equivalent Nb(5)N6 octahedra, edges with two equivalent Nb(8)N6 octahedra,  an edgeedge with one Nb(2)N5 square pyramid,  an edgeedge with one Nb(3)N5 square pyramid,  an edgeedge with one Nb(4)N5 square pyramid, and  an edgeedge with one Nb(6)N5 square pyramid. In the third Nb site, Nb(3) is bonded to one N(1), one N(2), one N(3), one N(4), and one N(7) atom to form NbN5 square pyramids that share corners with two equivalent Nb(4)N5 square pyramids, corners with three equivalent Nb(2)N5 square pyramids, corners with three equivalent Nb(3)N5 square pyramids,  an edgeedge with one Nb(5)N6 octahedra, edges with two equivalent Nb(8)N6 octahedra,  an edgeedge with one Nb(2)N5 square pyramid,  an edgeedge with one Nb(3)N5 square pyramid,  an edgeedge with one Nb(6)N5 square pyramid, and edges with two equivalent Nb(7)N5 square pyramids. In the fourth Nb site, Nb(4) is bonded to one N(5), two equivalent N(4), and two equivalent N(7) atoms to form NbN5 square pyramids that share corners with two equivalent Nb(8)N6 octahedra, corners with three equivalent Nb(5)N6 octahedra, corners with four equivalent Nb(3)N5 square pyramids,  an edgeedge with one Nb(8)N6 octahedra,  an edgeedge with one Nb(6)N5 square pyramid, edges with two equivalent Nb(2)N5 square pyramids, and edges with two equivalent Nb(7)N5 square pyramids. The corner-sharing octahedral tilt angles range from 0-4°. In the fifth Nb site, Nb(5) is bonded to one N(1), one N(5), two equivalent N(4), and two equivalent N(6) atoms to form NbN6 octahedra that share  a cornercorner with one Nb(8)N6 octahedra, corners with two equivalent Nb(6)N5 square pyramids, corners with three equivalent Nb(4)N5 square pyramids,  an edgeedge with one Nb(5)N6 octahedra,  an edgeedge with one Nb(7)N5 square pyramid, edges with two equivalent Nb(3)N5 square pyramids, edges with two equivalent Nb(6)N5 square pyramids, and edges with four equivalent Nb(2)N5 square pyramids. The corner-sharing octahedra are not tilted. In the sixth Nb site, Nb(6) is bonded to one N(3), two equivalent N(4), and two equivalent N(6) atoms to form NbN5 square pyramids that share  a cornercorner with one Nb(8)N6 octahedra, corners with two equivalent Nb(5)N6 octahedra, corners with two equivalent Nb(2)N5 square pyramids, corners with two equivalent Nb(7)N5 square pyramids, edges with two equivalent Nb(5)N6 octahedra,  an edgeedge with one Nb(4)N5 square pyramid,  an edgeedge with one Nb(6)N5 square pyramid, edges with two equivalent Nb(2)N5 square pyramids, and edges with two equivalent Nb(3)N5 square pyramids. The corner-sharing octahedral tilt angles range from 0-3°. In the seventh Nb site, Nb(7) is bonded to one N(2), two equivalent N(4), and two equivalent N(7) atoms to form NbN5 square pyramids that share corners with two equivalent Nb(8)N6 octahedra,  a cornercorner with one Nb(7)N5 square pyramid, corners with two equivalent Nb(2)N5 square pyramids, corners with two equivalent Nb(6)N5 square pyramids,  an edgeedge with one Nb(5)N6 octahedra,  an edgeedge with one Nb(8)N6 octahedra, edges with two equivalent Nb(4)N5 square pyramids, and edges with four equivalent Nb(3)N5 square pyramids. The corner-sharing octahedral tilt angles are 2°. In the eighth Nb site, Nb(8) is bonded to one N(1), one N(3), and four equivalent N(7) atoms to form NbN6 octahedra that share  a cornercorner with one Nb(5)N6 octahedra,  a cornercorner with one Nb(6)N5 square pyramid, corners with two equivalent Nb(4)N5 square pyramids, corners with two equivalent Nb(7)N5 square pyramids, edges with two equivalent Nb(8)N6 octahedra,  an edgeedge with one Nb(4)N5 square pyramid,  an edgeedge with one Nb(7)N5 square pyramid, edges with four equivalent Nb(2)N5 square pyramids, and edges with four equivalent Nb(3)N5 square pyramids. The corner-sharing octahedra are not tilted. There are seven inequivalent N sites. In the first N site, N(1) is bonded to one Nb(5), one Nb(8), two equivalent Nb(2), and two equivalent Nb(3) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedra are not tilted. In the second N site, N(2) is bonded to two equivalent Nb(7) and four equivalent Nb(3) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles are 5°. In the third N site, N(3) is bonded to one Nb(6), one Nb(8), two equivalent Nb(2), and two equivalent Nb(3) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the fourth N site, N(4) is bonded to one Nb(1), one Nb(3), one Nb(4), one Nb(5), one Nb(6), and one Nb(7) atom to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the fifth N site, N(5) is bonded to one Nb(4), one Nb(5), two equivalent Nb(1), and two equivalent Nb(2) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the sixth N site, N(6) is bonded to two equivalent Nb(2), two equivalent Nb(5), and two equivalent Nb(6) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the seventh N site, N(7) is bonded to one Nb(2), one Nb(3), one Nb(4), one Nb(7), and two equivalent Nb(8) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles range from 1-8°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Nb20N17
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.284
_cell_length_b   8.284
_cell_length_c   10.358
_cell_angle_alpha   62.709
_cell_angle_beta   62.709
_cell_angle_gamma   44.483
_symmetry_Int_Tables_number   1
_cell_volume   432.658
_cell_formula_units_Z   1
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
  Nb  Nb0  1  0.000  0.500  0.000  1.0
  Nb  Nb1  1  0.609  0.089  0.195  1.0
  Nb  Nb2  1  0.714  0.190  0.404  1.0
  Nb  Nb3  1  0.190  0.714  0.404  1.0
  Nb  Nb4  1  0.286  0.810  0.596  1.0
  Nb  Nb5  1  0.860  0.860  0.687  1.0
  Nb  Nb6  1  0.810  0.286  0.596  1.0
  Nb  Nb7  1  0.911  0.391  0.805  1.0
  Nb  Nb8  1  0.450  0.450  0.900  1.0
  Nb  Nb9  1  0.391  0.911  0.805  1.0
  Nb  Nb10  1  0.500  0.000  0.000  1.0
  Nb  Nb11  1  0.057  0.057  0.092  1.0
  Nb  Nb12  1  0.140  0.140  0.313  1.0
  Nb  Nb13  1  0.089  0.609  0.195  1.0
  Nb  Nb14  1  0.657  0.657  0.292  1.0
  Nb  Nb15  1  0.751  0.751  0.499  1.0
  Nb  Nb16  1  0.249  0.249  0.501  1.0
  Nb  Nb17  1  0.343  0.343  0.708  1.0
  Nb  Nb18  1  0.943  0.943  0.908  1.0
  Nb  Nb19  1  0.550  0.550  0.100  1.0
  N  N20  1  0.399  0.399  0.301  1.0
  N  N21  1  0.500  0.500  0.500  1.0
  N  N22  1  0.096  0.096  0.706  1.0
  N  N23  1  0.649  0.150  0.800  1.0
  N  N24  1  0.601  0.601  0.699  1.0
  N  N25  1  0.705  0.705  0.894  1.0
  N  N26  1  0.248  0.752  0.000  1.0
  N  N27  1  0.351  0.850  0.200  1.0
  N  N28  1  0.295  0.295  0.106  1.0
  N  N29  1  0.850  0.351  0.200  1.0
  N  N30  1  0.950  0.450  0.399  1.0
  N  N31  1  0.904  0.904  0.294  1.0
  N  N32  1  0.450  0.950  0.399  1.0
  N  N33  1  0.550  0.050  0.601  1.0
  N  N34  1  0.050  0.550  0.601  1.0
  N  N35  1  0.150  0.649  0.800  1.0
  N  N36  1  0.752  0.248  0.000  1.0
[/CIF]
.
The material structure described by Nb20N17 crystallizes in the monoclinic C2/m space group. There are eight inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a square co-planar geometry to two equivalent N(4) and two equivalent N(5) atoms. In the second Nb site, Nb(2) is bonded to one N(1), one N(3), one N(5), one N(6), and one N(7) atom to form NbN5 square pyramids that share  a cornercorner with one Nb(6)N5 square pyramid,  a cornercorner with one Nb(7)N5 square pyramid, corners with two equivalent Nb(2)N5 square pyramids, corners with three equivalent Nb(3)N5 square pyramids, edges with two equivalent Nb(5)N6 octahedra, edges with two equivalent Nb(8)N6 octahedra,  an edgeedge with one Nb(2)N5 square pyramid,  an edgeedge with one Nb(3)N5 square pyramid,  an edgeedge with one Nb(4)N5 square pyramid, and  an edgeedge with one Nb(6)N5 square pyramid. In the third Nb site, Nb(3) is bonded to one N(1), one N(2), one N(3), one N(4), and one N(7) atom to form NbN5 square pyramids that share corners with two equivalent Nb(4)N5 square pyramids, corners with three equivalent Nb(2)N5 square pyramids, corners with three equivalent Nb(3)N5 square pyramids,  an edgeedge with one Nb(5)N6 octahedra, edges with two equivalent Nb(8)N6 octahedra,  an edgeedge with one Nb(2)N5 square pyramid,  an edgeedge with one Nb(3)N5 square pyramid,  an edgeedge with one Nb(6)N5 square pyramid, and edges with two equivalent Nb(7)N5 square pyramids. In the fourth Nb site, Nb(4) is bonded to one N(5), two equivalent N(4), and two equivalent N(7) atoms to form NbN5 square pyramids that share corners with two equivalent Nb(8)N6 octahedra, corners with three equivalent Nb(5)N6 octahedra, corners with four equivalent Nb(3)N5 square pyramids,  an edgeedge with one Nb(8)N6 octahedra,  an edgeedge with one Nb(6)N5 square pyramid, edges with two equivalent Nb(2)N5 square pyramids, and edges with two equivalent Nb(7)N5 square pyramids. The corner-sharing octahedral tilt angles range from 0-4°. In the fifth Nb site, Nb(5) is bonded to one N(1), one N(5), two equivalent N(4), and two equivalent N(6) atoms to form NbN6 octahedra that share  a cornercorner with one Nb(8)N6 octahedra, corners with two equivalent Nb(6)N5 square pyramids, corners with three equivalent Nb(4)N5 square pyramids,  an edgeedge with one Nb(5)N6 octahedra,  an edgeedge with one Nb(7)N5 square pyramid, edges with two equivalent Nb(3)N5 square pyramids, edges with two equivalent Nb(6)N5 square pyramids, and edges with four equivalent Nb(2)N5 square pyramids. The corner-sharing octahedra are not tilted. In the sixth Nb site, Nb(6) is bonded to one N(3), two equivalent N(4), and two equivalent N(6) atoms to form NbN5 square pyramids that share  a cornercorner with one Nb(8)N6 octahedra, corners with two equivalent Nb(5)N6 octahedra, corners with two equivalent Nb(2)N5 square pyramids, corners with two equivalent Nb(7)N5 square pyramids, edges with two equivalent Nb(5)N6 octahedra,  an edgeedge with one Nb(4)N5 square pyramid,  an edgeedge with one Nb(6)N5 square pyramid, edges with two equivalent Nb(2)N5 square pyramids, and edges with two equivalent Nb(3)N5 square pyramids. The corner-sharing octahedral tilt angles range from 0-3°. In the seventh Nb site, Nb(7) is bonded to one N(2), two equivalent N(4), and two equivalent N(7) atoms to form NbN5 square pyramids that share corners with two equivalent Nb(8)N6 octahedra,  a cornercorner with one Nb(7)N5 square pyramid, corners with two equivalent Nb(2)N5 square pyramids, corners with two equivalent Nb(6)N5 square pyramids,  an edgeedge with one Nb(5)N6 octahedra,  an edgeedge with one Nb(8)N6 octahedra, edges with two equivalent Nb(4)N5 square pyramids, and edges with four equivalent Nb(3)N5 square pyramids. The corner-sharing octahedral tilt angles are 2°. In the eighth Nb site, Nb(8) is bonded to one N(1), one N(3), and four equivalent N(7) atoms to form NbN6 octahedra that share  a cornercorner with one Nb(5)N6 octahedra,  a cornercorner with one Nb(6)N5 square pyramid, corners with two equivalent Nb(4)N5 square pyramids, corners with two equivalent Nb(7)N5 square pyramids, edges with two equivalent Nb(8)N6 octahedra,  an edgeedge with one Nb(4)N5 square pyramid,  an edgeedge with one Nb(7)N5 square pyramid, edges with four equivalent Nb(2)N5 square pyramids, and edges with four equivalent Nb(3)N5 square pyramids. The corner-sharing octahedra are not tilted. There are seven inequivalent N sites. In the first N site, N(1) is bonded to one Nb(5), one Nb(8), two equivalent Nb(2), and two equivalent Nb(3) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedra are not tilted. In the second N site, N(2) is bonded to two equivalent Nb(7) and four equivalent Nb(3) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles are 5°. In the third N site, N(3) is bonded to one Nb(6), one Nb(8), two equivalent Nb(2), and two equivalent Nb(3) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the fourth N site, N(4) is bonded to one Nb(1), one Nb(3), one Nb(4), one Nb(5), one Nb(6), and one Nb(7) atom to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the fifth N site, N(5) is bonded to one Nb(4), one Nb(5), two equivalent Nb(1), and two equivalent Nb(2) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the sixth N site, N(6) is bonded to two equivalent Nb(2), two equivalent Nb(5), and two equivalent Nb(6) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the seventh N site, N(7) is bonded to one Nb(2), one Nb(3), one Nb(4), one Nb(7), and two equivalent Nb(8) atoms to form a mixture of corner and edge-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles range from 1-8°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Nb20N17
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.284
_cell_length_b   8.284
_cell_length_c   10.358
_cell_angle_alpha   62.709
_cell_angle_beta   62.709
_cell_angle_gamma   44.483
_symmetry_Int_Tables_number   1
_cell_volume   432.658
_cell_formula_units_Z   1
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
  Nb  Nb0  1  0.000  0.500  0.000  1.0
  Nb  Nb1  1  0.609  0.089  0.195  1.0
  Nb  Nb2  1  0.714  0.190  0.404  1.0
  Nb  Nb3  1  0.190  0.714  0.404  1.0
  Nb  Nb4  1  0.286  0.810  0.596  1.0
  Nb  Nb5  1  0.860  0.860  0.687  1.0
  Nb  Nb6  1  0.810  0.286  0.596  1.0
  Nb  Nb7  1  0.911  0.391  0.805  1.0
  Nb  Nb8  1  0.450  0.450  0.900  1.0
  Nb  Nb9  1  0.391  0.911  0.805  1.0
  Nb  Nb10  1  0.500  0.000  0.000  1.0
  Nb  Nb11  1  0.057  0.057  0.092  1.0
  Nb  Nb12  1  0.140  0.140  0.313  1.0
  Nb  Nb13  1  0.089  0.609  0.195  1.0
  Nb  Nb14  1  0.657  0.657  0.292  1.0
  Nb  Nb15  1  0.751  0.751  0.499  1.0
  Nb  Nb16  1  0.249  0.249  0.501  1.0
  Nb  Nb17  1  0.343  0.343  0.708  1.0
  Nb  Nb18  1  0.943  0.943  0.908  1.0
  Nb  Nb19  1  0.550  0.550  0.100  1.0
  N  N20  1  0.399  0.399  0.301  1.0
  N  N21  1  0.500  0.500  0.500  1.0
  N  N22  1  0.096  0.096  0.706  1.0
  N  N23  1  0.649  0.150  0.800  1.0
  N  N24  1  0.601  0.601  0.699  1.0
  N  N25  1  0.705  0.705  0.894  1.0
  N  N26  1  0.248  0.752  0.000  1.0
  N  N27  1  0.351  0.850  0.200  1.0
  N  N28  1  0.295  0.295  0.106  1.0
  N  N29  1  0.850  0.351  0.200  1.0
  N  N30  1  0.950  0.450  0.399  1.0
  N  N31  1  0.904  0.904  0.294  1.0
  N  N32  1  0.450  0.950  0.399  1.0
  N  N33  1  0.550  0.050  0.601  1.0
  N  N34  1  0.050  0.550  0.601  1.0
  N  N35  1  0.150  0.649  0.800  1.0
  N  N36  1  0.752  0.248  0.000  1.0
[/CIF]
.