data_NbCuB4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.2
_cell_length_b   4.2
_cell_length_c   4.2
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NbCuB4
_chemical_formula_sum   'Nb1 Cu1 B4'
_cell_volume   52.31
_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  Nb5  1  0.48  0.48  0.48  1.0
  Cu  Cu4  1  0.0  0.0  0.0  1.0
  B  B0  1  0.23  0.23  0.71  1.0
  B  B1  1  0.23  0.71  0.23  1.0
  B  B2  1  0.71  0.23  0.23  1.0
  B  B3  1  0.71  0.71  0.71  1.0

data_NbCuB4
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.2
_cell_length_b   4.2
_cell_length_c   10.28
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   NbCuB4
_chemical_formula_sum   'Nb3 Cu3 B12'
_cell_volume   156.92
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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  3  0.0  0.0  0.52  1.0
  Cu  Cu1  3  0.0  0.0  0.0  1.0
  B  B2  9  0.01  0.5  0.28  1.0
  B  B3  3  0.0  0.0  0.29  1.0

Nb Cu B B B B
Nb Cu B B B B 0 2 o o o 0 3 o o o 0 4 o o o 0 5 o o o 1 4 - o o 1 3 o - o 1 2 o o - 1 5 o - - 1 5 - o - 1 5 - - o 2 5 o - o 2 5 - o o 3 5 o o - 3 5 - o o 4 5 o o - 4 5 o - o 
NbCuB4 crystallizes in the trigonal R3m space group. Nb(1) is bonded in a 4-coordinate geometry to one B(2) and three equivalent B(1) atoms. The Nb(1)-B(2) bond length is 2.33 Å. All Nb(1)-B(1) bond lengths are 1.54 Å. Cu(1) is bonded in a trigonal non-coplanar geometry to three equivalent B(1) atoms. All Cu(1)-B(1) bond lengths are 1.37 Å. There are two inequivalent B sites. In the first B site, B(2) is bonded to one Nb(1) and six equivalent B(1) atoms to form distorted corner-sharing BNbB6 hexagonal pyramids. All B(2)-B(1) bond lengths are 2.10 Å. In the second B site, B(1) is bonded in a distorted linear geometry to one Nb(1), one Cu(1), and two equivalent B(2) atoms.