The crystal structure described by NaNb2AsO8 crystallizes in the monoclinic P2_1/c space group. Na(1) is bonded to one O(2), one O(3), one O(6), one O(7), one O(8), and two equivalent O(1) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent As(1)O4 tetrahedra, edges with two equivalent Nb(2)O6 octahedra,  an edgeedge with one Na(1)O7 pentagonal bipyramid, and  an edgeedge with one As(1)O4 tetrahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(5), one O(6), and one O(8) atom. In the second Nb site, Nb(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form NbO6 octahedra that share corners with three equivalent As(1)O4 tetrahedra and edges with two equivalent Na(1)O7 pentagonal bipyramids. As(1) is bonded to one O(2), one O(3), one O(7), and one O(8) atom to form AsO4 tetrahedra that share corners with three equivalent Nb(2)O6 octahedra, corners with two equivalent Na(1)O7 pentagonal bipyramids, and  an edgeedge with one Na(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 43-57°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Na(1) and one Nb(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Nb(2), and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(1), one Nb(2), and one As(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Nb(1) and one Nb(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(1), one Nb(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Na(1), one Nb(2), and one As(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Na(1), one Nb(1), and one As(1) atom. is represented by the CIF card [CIF]
data_NaNb2AsO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.760
_cell_length_b   4.982
_cell_length_c   15.352
_cell_angle_alpha   79.850
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   659.431
_cell_formula_units_Z   4
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
  Na  Na0  1  0.022  0.463  0.619  1.0
  Na  Na1  1  0.522  0.537  0.881  1.0
  Na  Na2  1  0.978  0.537  0.381  1.0
  Na  Na3  1  0.478  0.463  0.119  1.0
  Nb  Nb4  1  0.793  0.949  0.019  1.0
  Nb  Nb5  1  0.207  0.051  0.981  1.0
  Nb  Nb6  1  0.293  0.051  0.481  1.0
  Nb  Nb7  1  0.707  0.949  0.519  1.0
  Nb  Nb8  1  0.571  0.546  0.361  1.0
  Nb  Nb9  1  0.929  0.546  0.861  1.0
  Nb  Nb10  1  0.071  0.454  0.139  1.0
  Nb  Nb11  1  0.429  0.454  0.639  1.0
  As  As12  1  0.739  0.110  0.734  1.0
  As  As13  1  0.239  0.890  0.766  1.0
  As  As14  1  0.761  0.110  0.234  1.0
  As  As15  1  0.261  0.890  0.266  1.0
  O  O16  1  0.625  0.777  0.996  1.0
  O  O17  1  0.558  0.230  0.746  1.0
  O  O18  1  0.379  0.674  0.742  1.0
  O  O19  1  0.121  0.674  0.242  1.0
  O  O20  1  0.048  0.185  0.062  1.0
  O  O21  1  0.892  0.652  0.107  1.0
  O  O22  1  0.375  0.223  0.004  1.0
  O  O23  1  0.713  0.304  0.433  1.0
  O  O24  1  0.108  0.348  0.893  1.0
  O  O25  1  0.879  0.326  0.758  1.0
  O  O26  1  0.244  0.206  0.701  1.0
  O  O27  1  0.783  0.103  0.625  1.0
  O  O28  1  0.875  0.777  0.496  1.0
  O  O29  1  0.608  0.652  0.607  1.0
  O  O30  1  0.452  0.185  0.562  1.0
  O  O31  1  0.213  0.696  0.067  1.0
  O  O32  1  0.287  0.696  0.567  1.0
  O  O33  1  0.217  0.897  0.375  1.0
  O  O34  1  0.756  0.794  0.299  1.0
  O  O35  1  0.942  0.230  0.246  1.0
  O  O36  1  0.058  0.770  0.754  1.0
  O  O37  1  0.125  0.223  0.504  1.0
  O  O38  1  0.442  0.770  0.254  1.0
  O  O39  1  0.256  0.206  0.201  1.0
  O  O40  1  0.717  0.103  0.125  1.0
  O  O41  1  0.621  0.326  0.258  1.0
  O  O42  1  0.787  0.304  0.933  1.0
  O  O43  1  0.548  0.815  0.438  1.0
  O  O44  1  0.952  0.815  0.938  1.0
  O  O45  1  0.744  0.794  0.799  1.0
  O  O46  1  0.283  0.897  0.875  1.0
  O  O47  1  0.392  0.348  0.393  1.0
[/CIF]
.
The crystal structure described by NaNb2AsO8 crystallizes in the monoclinic P2_1/c space group. Na(1) is bonded to one O(2), one O(3), one O(6), one O(7), one O(8), and two equivalent O(1) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent As(1)O4 tetrahedra, edges with two equivalent Nb(2)O6 octahedra,  an edgeedge with one Na(1)O7 pentagonal bipyramid, and  an edgeedge with one As(1)O4 tetrahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(5), one O(6), and one O(8) atom. In the second Nb site, Nb(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form NbO6 octahedra that share corners with three equivalent As(1)O4 tetrahedra and edges with two equivalent Na(1)O7 pentagonal bipyramids. As(1) is bonded to one O(2), one O(3), one O(7), and one O(8) atom to form AsO4 tetrahedra that share corners with three equivalent Nb(2)O6 octahedra, corners with two equivalent Na(1)O7 pentagonal bipyramids, and  an edgeedge with one Na(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 43-57°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Na(1) and one Nb(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Nb(2), and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(1), one Nb(2), and one As(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Nb(1) and one Nb(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(1), one Nb(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Na(1), one Nb(2), and one As(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Na(1), one Nb(1), and one As(1) atom. is represented by the CIF card [CIF]
data_NaNb2AsO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.760
_cell_length_b   4.982
_cell_length_c   15.352
_cell_angle_alpha   79.850
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   659.431
_cell_formula_units_Z   4
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
  Na  Na0  1  0.022  0.463  0.619  1.0
  Na  Na1  1  0.522  0.537  0.881  1.0
  Na  Na2  1  0.978  0.537  0.381  1.0
  Na  Na3  1  0.478  0.463  0.119  1.0
  Nb  Nb4  1  0.793  0.949  0.019  1.0
  Nb  Nb5  1  0.207  0.051  0.981  1.0
  Nb  Nb6  1  0.293  0.051  0.481  1.0
  Nb  Nb7  1  0.707  0.949  0.519  1.0
  Nb  Nb8  1  0.571  0.546  0.361  1.0
  Nb  Nb9  1  0.929  0.546  0.861  1.0
  Nb  Nb10  1  0.071  0.454  0.139  1.0
  Nb  Nb11  1  0.429  0.454  0.639  1.0
  As  As12  1  0.739  0.110  0.734  1.0
  As  As13  1  0.239  0.890  0.766  1.0
  As  As14  1  0.761  0.110  0.234  1.0
  As  As15  1  0.261  0.890  0.266  1.0
  O  O16  1  0.625  0.777  0.996  1.0
  O  O17  1  0.558  0.230  0.746  1.0
  O  O18  1  0.379  0.674  0.742  1.0
  O  O19  1  0.121  0.674  0.242  1.0
  O  O20  1  0.048  0.185  0.062  1.0
  O  O21  1  0.892  0.652  0.107  1.0
  O  O22  1  0.375  0.223  0.004  1.0
  O  O23  1  0.713  0.304  0.433  1.0
  O  O24  1  0.108  0.348  0.893  1.0
  O  O25  1  0.879  0.326  0.758  1.0
  O  O26  1  0.244  0.206  0.701  1.0
  O  O27  1  0.783  0.103  0.625  1.0
  O  O28  1  0.875  0.777  0.496  1.0
  O  O29  1  0.608  0.652  0.607  1.0
  O  O30  1  0.452  0.185  0.562  1.0
  O  O31  1  0.213  0.696  0.067  1.0
  O  O32  1  0.287  0.696  0.567  1.0
  O  O33  1  0.217  0.897  0.375  1.0
  O  O34  1  0.756  0.794  0.299  1.0
  O  O35  1  0.942  0.230  0.246  1.0
  O  O36  1  0.058  0.770  0.754  1.0
  O  O37  1  0.125  0.223  0.504  1.0
  O  O38  1  0.442  0.770  0.254  1.0
  O  O39  1  0.256  0.206  0.201  1.0
  O  O40  1  0.717  0.103  0.125  1.0
  O  O41  1  0.621  0.326  0.258  1.0
  O  O42  1  0.787  0.304  0.933  1.0
  O  O43  1  0.548  0.815  0.438  1.0
  O  O44  1  0.952  0.815  0.938  1.0
  O  O45  1  0.744  0.794  0.799  1.0
  O  O46  1  0.283  0.897  0.875  1.0
  O  O47  1  0.392  0.348  0.393  1.0
[/CIF]
.