The crystal structure described by CuNb2O6 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with four equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-55°. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), one O(5), one O(6), and two equivalent O(3) atoms. Cu(1) is bonded to one O(1), one O(5), two equivalent O(2), and two equivalent O(6) atoms to form CuO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra and edges with two equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-55°. There are six inequivalent O sites. In the first O site, O(6) is bonded in a 3-coordinate geometry to one Nb(2) and two equivalent Cu(1) atoms. In the second O site, O(1) is bonded in a trigonal planar geometry to one Nb(1), one Nb(2), and one Cu(1) atom. In the third O site, O(2) is bonded in a distorted trigonal planar geometry to one Nb(1) and two equivalent Cu(1) atoms. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Nb(2) atoms. In the fifth O site, O(4) is bonded in a distorted trigonal planar geometry to one Nb(2) and two equivalent Nb(1) atoms. In the sixth O site, O(5) is bonded in a distorted trigonal planar geometry to one Nb(1), one Nb(2), and one Cu(1) atom. is represented by the CIF file [CIF]
data_Nb2CuO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   14.356
_cell_length_b   5.057
_cell_length_c   5.874
_cell_angle_alpha   87.758
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   426.170
_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
  Nb  Nb0  1  0.158  0.261  0.204  1.0
  Nb  Nb1  1  0.658  0.739  0.296  1.0
  Nb  Nb2  1  0.842  0.739  0.796  1.0
  Nb  Nb3  1  0.342  0.261  0.704  1.0
  Nb  Nb4  1  0.162  0.768  0.844  1.0
  Nb  Nb5  1  0.662  0.232  0.656  1.0
  Nb  Nb6  1  0.838  0.232  0.156  1.0
  Nb  Nb7  1  0.338  0.768  0.344  1.0
  Cu  Cu8  1  0.002  0.749  0.345  1.0
  Cu  Cu9  1  0.502  0.251  0.155  1.0
  Cu  Cu10  1  0.998  0.251  0.655  1.0
  Cu  Cu11  1  0.498  0.749  0.845  1.0
  O  O12  1  0.096  0.934  0.139  1.0
  O  O13  1  0.596  0.066  0.361  1.0
  O  O14  1  0.904  0.066  0.861  1.0
  O  O15  1  0.404  0.934  0.639  1.0
  O  O16  1  0.076  0.428  0.401  1.0
  O  O17  1  0.576  0.572  0.099  1.0
  O  O18  1  0.924  0.572  0.599  1.0
  O  O19  1  0.424  0.428  0.901  1.0
  O  O20  1  0.246  0.598  0.150  1.0
  O  O21  1  0.746  0.402  0.350  1.0
  O  O22  1  0.754  0.402  0.850  1.0
  O  O23  1  0.254  0.598  0.650  1.0
  O  O24  1  0.245  0.099  0.908  1.0
  O  O25  1  0.745  0.901  0.592  1.0
  O  O26  1  0.755  0.901  0.092  1.0
  O  O27  1  0.255  0.099  0.408  1.0
  O  O28  1  0.098  0.445  0.926  1.0
  O  O29  1  0.598  0.555  0.574  1.0
  O  O30  1  0.902  0.555  0.074  1.0
  O  O31  1  0.402  0.445  0.426  1.0
  O  O32  1  0.078  0.944  0.656  1.0
  O  O33  1  0.578  0.056  0.844  1.0
  O  O34  1  0.922  0.056  0.344  1.0
  O  O35  1  0.422  0.944  0.156  1.0
[/CIF]
.
The crystal structure described by CuNb2O6 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with four equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-55°. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), one O(5), one O(6), and two equivalent O(3) atoms. Cu(1) is bonded to one O(1), one O(5), two equivalent O(2), and two equivalent O(6) atoms to form CuO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra and edges with two equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-55°. There are six inequivalent O sites. In the first O site, O(6) is bonded in a 3-coordinate geometry to one Nb(2) and two equivalent Cu(1) atoms. In the second O site, O(1) is bonded in a trigonal planar geometry to one Nb(1), one Nb(2), and one Cu(1) atom. In the third O site, O(2) is bonded in a distorted trigonal planar geometry to one Nb(1) and two equivalent Cu(1) atoms. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Nb(2) atoms. In the fifth O site, O(4) is bonded in a distorted trigonal planar geometry to one Nb(2) and two equivalent Nb(1) atoms. In the sixth O site, O(5) is bonded in a distorted trigonal planar geometry to one Nb(1), one Nb(2), and one Cu(1) atom. is represented by the CIF file [CIF]
data_Nb2CuO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   14.356
_cell_length_b   5.057
_cell_length_c   5.874
_cell_angle_alpha   87.758
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   426.170
_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
  Nb  Nb0  1  0.158  0.261  0.204  1.0
  Nb  Nb1  1  0.658  0.739  0.296  1.0
  Nb  Nb2  1  0.842  0.739  0.796  1.0
  Nb  Nb3  1  0.342  0.261  0.704  1.0
  Nb  Nb4  1  0.162  0.768  0.844  1.0
  Nb  Nb5  1  0.662  0.232  0.656  1.0
  Nb  Nb6  1  0.838  0.232  0.156  1.0
  Nb  Nb7  1  0.338  0.768  0.344  1.0
  Cu  Cu8  1  0.002  0.749  0.345  1.0
  Cu  Cu9  1  0.502  0.251  0.155  1.0
  Cu  Cu10  1  0.998  0.251  0.655  1.0
  Cu  Cu11  1  0.498  0.749  0.845  1.0
  O  O12  1  0.096  0.934  0.139  1.0
  O  O13  1  0.596  0.066  0.361  1.0
  O  O14  1  0.904  0.066  0.861  1.0
  O  O15  1  0.404  0.934  0.639  1.0
  O  O16  1  0.076  0.428  0.401  1.0
  O  O17  1  0.576  0.572  0.099  1.0
  O  O18  1  0.924  0.572  0.599  1.0
  O  O19  1  0.424  0.428  0.901  1.0
  O  O20  1  0.246  0.598  0.150  1.0
  O  O21  1  0.746  0.402  0.350  1.0
  O  O22  1  0.754  0.402  0.850  1.0
  O  O23  1  0.254  0.598  0.650  1.0
  O  O24  1  0.245  0.099  0.908  1.0
  O  O25  1  0.745  0.901  0.592  1.0
  O  O26  1  0.755  0.901  0.092  1.0
  O  O27  1  0.255  0.099  0.408  1.0
  O  O28  1  0.098  0.445  0.926  1.0
  O  O29  1  0.598  0.555  0.574  1.0
  O  O30  1  0.902  0.555  0.074  1.0
  O  O31  1  0.402  0.445  0.426  1.0
  O  O32  1  0.078  0.944  0.656  1.0
  O  O33  1  0.578  0.056  0.844  1.0
  O  O34  1  0.922  0.056  0.344  1.0
  O  O35  1  0.422  0.944  0.156  1.0
[/CIF]
.