data_NaNb2Cu
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.34
_cell_length_b   3.34
_cell_length_c   7.37
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaNb2Cu
_chemical_formula_sum   'Na1 Nb2 Cu1'
_cell_volume   82.44
_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
  Na  Na1  1  0.0  0.0  0.34  1.0
  Nb  Nb2  1  0.67  0.67  0.55  1.0
  Nb  Nb3  1  0.0  0.0  0.88  1.0
  Cu  Cu0  1  0.67  0.67  0.29  1.0

data_NaNb2Cu
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.73
_cell_length_b   4.73
_cell_length_c   7.37
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   NaNb2Cu
_chemical_formula_sum   'Na2 Nb4 Cu2'
_cell_volume   164.87
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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  2  0.0  0.0  0.34  1.0
  Nb  Nb1  2  0.0  0.0  0.88  1.0
  Nb  Nb2  2  0.17  0.5  0.55  1.0
  Cu  Cu3  2  0.17  0.5  0.29  1.0

Na Nb Nb Cu
Na Nb Nb Cu 0 3 - - o 0 1 - - o 0 2 o o - 1 3 o o o 1 2 + + o 1 2 + o o 1 2 o + o 2 3 - - + 2 2 + o o 2 2 o + o 
NaNb2Cu crystallizes in the monoclinic Cm space group. Na(1) is bonded in a distorted single-bond geometry to one Nb(1), one Nb(2), and one Cu(1) atom. The Na(1)-Nb(1) bond length is 2.16 Å. The Na(1)-Nb(2) bond length is 3.44 Å. The Na(1)-Cu(1) bond length is 1.60 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 2-coordinate geometry to one Na(1), three equivalent Nb(2), and one Cu(1) atom. There is one shorter (2.88 Å) and two longer (3.49 Å) Nb(1)-Nb(2) bond lengths. The Nb(1)-Cu(1) bond length is 1.88 Å. In the second Nb site, Nb(2) is bonded in a 9-coordinate geometry to one Na(1), three equivalent Nb(1), four equivalent Nb(2), and one Cu(1) atom. All Nb(2)-Nb(2) bond lengths are 3.34 Å. The Nb(2)-Cu(1) bond length is 3.43 Å. Cu(1) is bonded in a 1-coordinate geometry to one Na(1), one Nb(1), and one Nb(2) atom.