data_TaCu5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.78
_cell_length_b   4.78
_cell_length_c   4.78
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   TaCu5
_chemical_formula_sum   'Ta1 Cu5'
_cell_volume   77.38
_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
  Ta  Ta5  1  0.07  0.07  0.07  1.0
  Cu  Cu0  1  0.0  0.0  0.0  1.0
  Cu  Cu1  1  0.53  0.53  0.53  1.0
  Cu  Cu2  1  0.23  0.23  0.53  1.0
  Cu  Cu3  1  0.53  0.23  0.23  1.0
  Cu  Cu4  1  0.23  0.53  0.23  1.0

data_TaCu5
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.78
_cell_length_b   4.78
_cell_length_c   11.72
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   TaCu5
_chemical_formula_sum   'Ta3 Cu15'
_cell_volume   232.15
_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
  Ta  Ta0  3  0.0  0.0  0.93  1.0
  Cu  Cu1  9  0.1  0.2  0.67  1.0
  Cu  Cu2  3  0.0  0.0  0.0  1.0
  Cu  Cu3  3  0.0  0.0  0.47  1.0

Ta Cu Cu Cu Cu Cu
TaCu5 crystallizes in the trigonal R3m space group. Ta(1) is bonded in a single-bond geometry to one Cu(1), three equivalent Cu(2), and three equivalent Cu(3) atoms. The Ta(1)-Cu(1) bond length is 0.86 Å. All Ta(1)-Cu(2) bond lengths are 3.14 Å. All Ta(1)-Cu(3) bond lengths are 2.11 Å. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a single-bond geometry to one Ta(1), three equivalent Cu(2), and three equivalent Cu(3) atoms. All Cu(1)-Cu(2) bond lengths are 3.16 Å. All Cu(1)-Cu(3) bond lengths are 1.92 Å. In the second Cu site, Cu(2) is bonded in a 15-coordinate geometry to three equivalent Ta(1), three equivalent Cu(1), and nine equivalent Cu(3) atoms. There are three shorter (2.53 Å) and six longer (2.88 Å) Cu(2)-Cu(3) bond lengths. In the third Cu site, Cu(3) is bonded in a 4-coordinate geometry to one Ta(1), one Cu(1), two equivalent Cu(3), and three equivalent Cu(2) atoms. Both Cu(3)-Cu(3) bond lengths are 1.46 Å.